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Checking references for intended status: Informational ---------------------------------------------------------------------------- No issues found here. Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force J. Livingood 3 Internet-Draft N. Mody 4 Intended status: Informational M. O'Reirdan 5 Expires: October 23, 2010 Comcast 6 April 21, 2010 8 Recommendations for the Remediation of Bots in ISP Networks 9 draft-oreirdan-mody-bot-remediation-08 11 Abstract 13 This document contains recommendations on how Internet Service 14 Providers can manage the effects of computers used by their 15 subscribers, which have been infected with malicious bots, via 16 various remediation techniques. Internet users with infected 17 computers are exposed to risks such as loss of personal data, as well 18 as increased susceptibility to online fraud and/or phishing. Such 19 computers can also become an inadvertent participant in or component 20 of an online crime network, spam network, and/or phishing network, as 21 well as be used as a part of a distributed denial of service attack. 22 Mitigating the effects of and remediating the installations of 23 malicious bots will make it more difficult for botnets to operate and 24 could reduce the level of online crime on the Internet in general 25 and/or on a particular Internet Service Provider's network. 27 Status of this Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at http://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on October 23, 2010. 44 Copyright Notice 46 Copyright (c) 2010 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (http://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 This document may contain material from IETF Documents or IETF 60 Contributions published or made publicly available before November 61 10, 2008. The person(s) controlling the copyright in some of this 62 material may not have granted the IETF Trust the right to allow 63 modifications of such material outside the IETF Standards Process. 64 Without obtaining an adequate license from the person(s) controlling 65 the copyright in such materials, this document may not be modified 66 outside the IETF Standards Process, and derivative works of it may 67 not be created outside the IETF Standards Process, except to format 68 it for publication as an RFC or to translate it into languages other 69 than English. 71 Table of Contents 73 1. Requirements Language . . . . . . . . . . . . . . . . . . . . 4 74 2. Key Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 75 3. Introduction and Problem Statement . . . . . . . . . . . . . . 6 76 4. Important Notice of Limitations and Scope . . . . . . . . . . 8 77 5. Detection of Bots . . . . . . . . . . . . . . . . . . . . . . 8 78 6. Notification to Internet Users . . . . . . . . . . . . . . . . 12 79 7. Remediation of Hosts Infected with a Bot . . . . . . . . . . . 18 80 8. Guided Remediation Process . . . . . . . . . . . . . . . . . . 19 81 9. Professionally-Assisted Remediation Process . . . . . . . . . 21 82 10. Sharing of Data from the User to the ISP . . . . . . . . . . . 21 83 11. Security Considerations . . . . . . . . . . . . . . . . . . . 22 84 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 85 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 23 86 14. Informative references . . . . . . . . . . . . . . . . . . . . 24 87 Appendix A. Document Change Log . . . . . . . . . . . . . . . . . 25 88 Appendix B. Open Issues . . . . . . . . . . . . . . . . . . . . . 27 89 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 28 91 1. Requirements Language 93 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 94 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 95 document are to be interpreted as described in [RFC2119]. 97 2. Key Terminology 99 This section defines the key terms used in this document. 101 2.1. Malicious Bots, or Bots 103 A malicious or potentially malicious "bot" (derived from the word 104 "robot", hereafter simply referred to as a "bot") refers to a program 105 that is installed on a system in order to enable that system to 106 automatically (or semi-automatically) perform a task or set of tasks 107 typically under the command and control of a remote administrator, or 108 "bot master." Bots are also known as "zombies". Such bots may have 109 been installed surreptitiously, without the user's full understanding 110 of what the bot will do once installed, unknowingly as part of 111 another software installation, under false pretenses, and/or in a 112 variety of other possible ways. 114 It is important to note that there are 'good', or benign bots. Such 115 benign bots are often found in such environments such as gaming and 116 Internet Relay Chat (IRC) [RFC1459], where a continual, interactive 117 presence can be a requirement for participating in the games, 118 interacting with a computing resource, or other purposes. Since such 119 benign bots are performing useful, lawful, and non-disruptive 120 functions, there is no reason for a provider to monitor for their 121 presence and/or alert users to their presence. 123 Thus, while there may be benign, or harmless bots, for the purposes 124 of this document all mention of bots shall assume that the bots 125 involved are malicious or potentially malicious in nature. Such 126 malicious bots shall generally be assumed to have been deployed 127 without the permission or conscious understanding of a particular 128 Internet user. Thus, without a user's knowledge, bots may transform 129 the user's computing device into a platform from which malicious 130 activities can be conducted. In addition, included explicitly in 131 this category are potentially malicious bots, which may initially 132 appear neutral but may simply be waiting for remote instructions to 133 transform itself and/or otherwise begin engaging in malicious 134 behavior. In general, installation of a malicious bot without user 135 knowledge and consent is considered in most regions to be unlawful, 136 and the activities of malicious bots typically involve unlawful or 137 other maliciously disruptive activities. 139 2.2. Bot Networks, or Botnets 141 These are defined as concerted networks of bots capable of acting on 142 instructions generated remotely. The malicious activities are either 143 focused on the information on the local machine or acting to provide 144 services for remote machines. Bots are highly customizable so they 145 can be programmed to do many things. The major malicious activities 146 include but are not limited to: identity theft, spam, spim (spam over 147 instant messaging), spit (spam over Internet telephony), email 148 address harvesting, distributed denial of service (DDoS) attacks, 149 key-logging, fraudulent DNS pharming (redirection), hosting proxy 150 services, fast flux hosting, hosting of illegal content, use in man- 151 in-the-middle attacks, and click fraud. 153 Infection vectors include un-patched operating systems, software 154 vulnerabilities (which include so-called zero-day vulnerabilities 155 where no patch yet exists), weak/non-existent passwords, malicious 156 websites, un-patched browsers, malware, vulnerable helper 157 applications and social engineering techniques to gain access to the 158 user's computer. The detection and destruction of bots is an ongoing 159 issue and also a constant battle between the internet security 160 community, network security engineers and bot developers. 162 Initially, some bots used IRC to communicate but were easy to 163 shutdown if the command and control server was identified and 164 deactivated. Newer command and control methods have evolved, such 165 that those currently employed by bot masters make them much more 166 resistant to deactivation. With the introduction of P2P, HTTP and 167 other resilient communication protocols along with the widespread 168 adoption of encryption, bots are considerably more difficult to 169 identify and isolate from typical network usage. As a result 170 increased reliance is being placed on anomaly detection and 171 behavioral analysis, both locally and remotely, to identify bots. 173 2.3. Host 175 An end user's host, or computer, as used in the context of this 176 document, is intended to refer to a computing device that connects to 177 the Internet. This encompasses devices used by Internet users such 178 as personal computers, including laptops, desktops, and netbooks, as 179 well as mobile phones, smart phones, home gateway devices, and other 180 end user computing devices which are connected or can connect to the 181 public Internet and/or private IP networks. 183 Increasingly, other household systems and devices contain embedded 184 hosts which are connected to or can connect to the public Internet 185 and/or private IP networks. However, these devices may not be under 186 interactive control of the Internet user, such as may be the case 187 with various smart home and smart grid devices. 189 2.4. Malware 191 This is short for malicious software. In this case, malicious bots 192 are considered a subset of malware. Other forms of malware could 193 include viruses and other similar types of software. Internet users 194 can sometimes cause their host to be infected with malware, which may 195 include a bot or cause a bot to install itself, via inadvertently 196 accessing a specific website, downloading a file, or other 197 activities. 199 In other cases, Internet-connected hosts may become infected with 200 malware through externally initiated malicious activities such as the 201 exploitation of vulnerabilities or the brute force guessing of access 202 credentials. 204 2.5. Fast Flux 206 DNS Fast Fluxing occurs when a domain is bound in DNS using A records 207 to multiple IP addresses, each of which has a very short Time To Live 208 (TTL) value associated with it. This means that the domain resolves 209 to varying IP addresses over a short period of time. 211 DNS Fast Flux is typically used in conjunction with proxies which 212 then route the web requests to the real host which serves the data 213 being sought. The proxies are normally run on compromised user 214 hosts. The effect of this is to make the detection of the real host 215 for a piece of content much more difficult and to ensure that the 216 backend or hidden site remains up for as long as possible. 218 3. Introduction and Problem Statement 220 Hosts used by Internet users, which in this case are customers of an 221 Internet Service Provider (ISP), can be infected with malware which 222 may contain and/or install one or more bots on a host. They can 223 present a major problem for an ISP for a number of reasons (not to 224 mention of course the problems created for users). First, these bots 225 can be used to send spam, in some cases very large volumes of spam 226 [Spamalytics: An Empirical Analysis of Spam Marketing Conversion]. 227 This spam can result in extra cost for the ISPs in terms of wasted 228 network, server, and/or personnel resources, among many other 229 potential costs and side effects. Such spam can also negatively 230 affect the reputation of the ISP, their customers, and the email 231 reputation of the IP address space used by the ISP (often referred to 232 simply as 'IP reputation'). 234 In addition, these bots can act as platforms for directing, 235 participating in, or otherwise conducting attacks on critical 236 Internet infrastructure [Emerging Cyber Threats Report for 2009: 237 Data, Mobility and Questions of Responsibility will Drive Cyber 238 Threats in 2009 and Beyond]. Bots are frequently used as part of 239 coordinated Distributed Denial of Service (DDoS) attacks for 240 criminal, political or other motivations [The Gh0st in the Shell: 241 Network Security in the Himalayas] [The snooping dragon: 242 social-malware surveillance of the Tibetan movement]. For example, 243 bots have been used to attack Internet resources and infrastructure 244 ranging from web sites, to email servers and DNS servers, as well as 245 the critical Internet infrastructure of entire countries [Battling 246 Botnets and Online Mobs: Estonia's Defense Efforts during the 247 Internet War] [Cyberspace as a Combat Zone: The Phenomenon of 248 Electronic Jihad]. Motivations for such coordinated DDoS attacks can 249 range from criminal extortion attempts through to online protesting 250 and nationalistic fervor [Case Study: How a Bookmaker and a Whiz Kid 251 Took On a DDOS-based Online Extortion Attack]. 253 While any computing device can be infected with bots, the majority of 254 bot infections affect the personal computers used by Internet end 255 users. As a result of the role of ISPs in providing IP connectivity, 256 among many other services, to Internet users, these ISPs are in a 257 unique position to be able to attempt to detect and observe bot nets 258 operating in their networks. Furthermore, ISPs may also be in a 259 unique position to be able to notify their customers of actual, 260 potential, or likely infection by bots or other infection. 262 From an end user perspective, being notified that they may have an 263 infected computer on their network is very important information. 264 Once they know this, they can take steps to remove the bot, protect 265 themselves in the future, and resolve any problems which may stem 266 from the bot infection. Given that bots can consume vast amounts of 267 local computing and network resources, enable theft of personal 268 information (including personal financial information), enable the 269 host to be used for criminal activities (that may result in the 270 Internet user being legally culpable), destroy or leave the host in 271 an unrecoverable state via 'kill switch' bot technologies, it is 272 important to notify the user that they may be infected with a bot. 274 As a result, the intent of this document is to provide guidance to 275 ISPs and other organizations for the remediation of hosts infected 276 with bots, so as to reduce the size of bot nets and minimize the 277 potential harm that bots can inflict upon Internet infrastructure 278 generally, as well as on individual Internet users. Efforts by ISPs 279 and other organizations can, over time, reduce the pool of hosts 280 infected with bots on the Internet, which in turn could result in 281 smaller bot nets with less capability for disruption. 283 The potential mitigation of bots is accomplished through a process of 284 detection, notification to Internet users, and remediation of bot 285 infections with a variety of tools, as described later in this 286 document. 288 4. Important Notice of Limitations and Scope 290 The techniques described in this document in no way guarantee the 291 remediation of all bots. Bot removal is potentially a task requiring 292 specialized knowledge, skills and tools, and may be beyond the 293 ability of average users. Attempts at bot removal may frequently be 294 unsuccessful, or only partially successful, leaving the user's system 295 in an unstable and unsatisfactory state or even in a state where it 296 is still infected. Attempts at bot removal can result in side 297 effects ranging from a loss of data to partial or complete loss of 298 system usability. 300 In general, the only way a user can be sure they have removed some of 301 today's increasingly sophisticated malware is by 'nuking-and-paving' 302 the system: reformatting the drive, reinstalling the operating system 303 and applications (including all patches) from scratch, and then 304 restoring user files from a known clean backup. However the 305 introduction of persistent memory based malware may mean that, in 306 some cases, this may not be enough and may prove to be more than any 307 end user can be reasonably expected to resolve [Persistent Memory 308 Infection]. Experienced users would have to re-flash or re-image 309 persistent memory sections or components of their hosts in order to 310 remove persistent memory based malware. However, in some cases, not 311 even 'nuking-and-paving' the system will solve the problem, which 312 calls for hard drive replacement and/or complete replacement of the 313 host. 315 Devices with embedded operating systems, such as video gaming 316 consoles and smart home appliances, will most likely be beyond a 317 user's capability to remediate by themselves, and could therefore 318 require the aid of vendor-specific advice, updates and tools. 319 However, in some cases, such devices will have a function or switch 320 to enable the user to reset that device to a factory default 321 configuration, which may in some cases enable the user to remediate 322 the infection. Care must be taken when imparting remediation advice 323 to Internet users given the increasingly wide array of computing 324 devices that can be, or could be, infected by bots in the future. 326 5. Detection of Bots 328 An ISP must first identify that an Internet user, in this case a user 329 that is assumed to be their customer or otherwise connected to the 330 ISP's network, is determined to be infected, or likely to have been 331 infected with a bot. The ISP must attempt to detect the presence of 332 bots using methods, processes, and tools which maintain the privacy 333 of the personally identifiable information (PII) of their customers. 334 The ISP also must not block legitimate traffic in the course of bot 335 detection, and must instead employ detection methods, tools, and 336 processes which seek to be non-disruptive, as well as being 337 transparent to Internet users and end-user applications. 339 Detection methods, tools, and processes may include analysis of 340 specific network and/or application traffic flows (such as traffic to 341 an email server), analysis of aggregate network and/or application 342 traffic data, data feeds received from other ISPs and organizations 343 (such as lists of the ISP's IP addresses which have been reported to 344 have sent spam), feedback from the ISP's customers or other Internet 345 users, as well as a wide variety of other possibilities. In 346 practice, it has proven effective to validate a bot infect through 347 the use of a combination of multiple bot detection data points. This 348 can help to corroborate information of varying dependability or 349 consistency, as well as to avoid or minimize the possibility of false 350 positive identification of hosts. Detection should also, where 351 possible and feasible, attempt to classify the specific bot infection 352 type in order to confirm that it is malicious in nature, estimate the 353 variety and severity of threats it may pose (such as spam bot, key- 354 logging bot, file distribution bot, etc.), and to determine potential 355 methods for eventual remediation. However, given the dynamic nature 356 of botnet management and the criminal incentives to seek quick 357 financial rewards, botnets frequently update or change their core 358 malicious capabilities. As a consequence, botnets that are initially 359 detected and classified by the ISP as one particular type of bot need 360 to be continuously monitored and tracked in order to correctly 361 identify the threat they pose at any particular point in time. 363 Detection is also time-sensitive. If complex analysis is required 364 and multiple confirmations are needed to confirm a bot is indeed 365 present, then it is possible that the bot may cause some damage (to 366 either the infected host or a remotely targeted system) before it can 367 be stopped. This may mean that an ISP may need to balance the desire 368 or need to definitively classify and/or confirm a bot, which may take 369 an extended period of time, with the ability to predict the strong 370 likelihood of a bot in a very short period of time, provided that 371 such determinations have a relatively low false positive rate in 372 order to maintain the trust of users. This 'definitive-vs-likely' 373 challenge is difficult and, when in doubt, ISPs should probably err 374 on the side of caution by communicating when a likely bot infection 375 has taken place. This also means that Internet users may benefit 376 from the deployment of client-based software protections or other 377 software tools, which can enable rapid performance of heuristically- 378 based detection bot activity, such as the detection of a bot as it 379 starts to communicate to a bot net and execute commands. Any bot 380 detection systems should also be capable of adapting, either via 381 manual intervention or automatically, in order to cope with a rapidly 382 evolving threat. 384 As noted above, detection methods, tools, and processes should ensure 385 that privacy of customers' PII is maintained. While bot detection 386 methods, tools, and processes are similar to spam and virus defenses 387 deployed by the ISP for the benefit of their customers (and may be 388 directly related to those defenses), attempts to detect bots should 389 take into account the need of an ISP to take care to ensure any PII 390 collected or incidentally detected is properly protected. This is 391 important, as just as spam defenses may involve scanning the content 392 of email messages, which may contain PII, then so to may bot defenses 393 similarly come into incidental contact with PII. The definition of 394 PII varies from one jurisdiction to the next so proper care must be 395 taken to ensure that any actions taken comply with legislation and 396 good practice in the jurisdiction in which the PII is gathered. 397 Finally, depending upon the geographic region within which an ISP 398 operates, certain methods relating to bot detection may need to be 399 included in relevant terms of service documents or other documents 400 which are available to the customers of a particular ISP. 402 There are several bot detection methods, tools, and processes that an 403 ISP may choose to utilize, as noted in the list below. It is 404 important to note that the technical solutions available are 405 relatively immature, and are likely to change over time, evolving 406 rapidly in the coming years. While these items are described in 407 relation to ISPs, they may also be applicable to organizations 408 operating other networks, such as campus networks and enterprise 409 networks. 411 a. Where legally permissible or otherwise an industry accepted 412 practice in a particular market region, an ISP may in some manner 413 "scan" their IP space in order to detect un-patched or otherwise 414 vulnerable hosts, or to detect the signs of infection. This may 415 provide the ISP with the opportunity to easily identify Internet 416 users who appear to already be infected or are at great risk of 417 being infected with a bot. ISPs should note that some types of 418 port scanning may leave network services in a hung state or 419 render them unusable due to common frailties, and that many 420 modern firewall and host-based intrusion detection 421 implementations may alert the Internet user to the scan. As a 422 result the scan may be interpreted as a malicious attack against 423 the host. Vulnerability scanning has a higher probability of 424 leaving accessible network services and applications in a damaged 425 state and will often result in a higher probability of detection 426 by the Internet user and subsequent interpretation as a targeted 427 attack. Depending upon the vulnerability for which an ISP may be 428 scanning, some automated methods of vulnerability checking may 429 result in data being altered or created afresh on the Internet 430 user's host which be a problem in many legal environments. It 431 should also be noted that due to the prevalence of Network 432 Address Translation devices, Port Address Translation devices, 433 and/or firewall devices in user networks, network-based 434 vulnerability scanning may be of limited value. Thus, while we 435 note that this is one technique which may be utilized, it is 436 unlikely to be particularly effective and it has problematic side 437 effects, which leads the authors to recommend against the use of 438 this particular method. 440 b. An ISP may also communicate and share selected data, via feedback 441 loops or other mechanisms, with various third parties. Feedback 442 loops are consistently formatted feeds of real-time (or nearly 443 real-time) abuse reports offered by threat data clearinghouses, 444 security alert organizations, other ISPs, and other 445 organizations. The data may include, but is not limited to, 446 lists of the IP addresses of hosts which have or are likely to 447 have a bot running, domain names or fully qualified domain names 448 (FQDNs) known to host malware and/or be involved in the command 449 and control of botnets, IP addresses know to host malware and/or 450 be involved in the command and control of botnets, recently 451 tested or discovered techniques or detecting or remediating bot 452 infections, new threat vectors, and other relevant information. 453 Good examples of this include SNDS from Microsoft, XBL and PBL 454 from Spamhaus and the DSHIELD AS tool from the SANS Institute. 456 c. An ISP may use Netflow [RFC3954] or other similar passive network 457 monitoring to identify network anomalies that may be indicative 458 of botnet attacks or bot communications. For example, an ISP may 459 be able to identify compromised hosts by identifying traffic 460 destined to IP addresses associated with the command and control 461 of botnets, or destined to the combination of an IP address and 462 control port associated with a command and control network 463 (sometimes command and control traffic comes from a host which 464 has legitimate traffic). In addition, bots may be identified 465 when a remote host is under a DDoS attack, because hosts 466 participating in the attack will likely be infected by a bot, 467 frequently as observed at network borders (though ISPs should 468 beware of source IP address spoofing techniques to avoid or 469 confuse detection). 471 d. An ISP may use DNS-based techniques to perform detection. For 472 example, a given classified bot may be known to query a specific 473 list of domain names at specific times or on specific dates (in 474 the example of the so-called "Conficker" bot), often by matching 475 DNS queries to a well known list of domains associated with 476 malware. In many cases such lists are distributed by or shared 477 using third parties, such as threat data clearinghouses. 479 e. User complaints: Because hosts infected by bots are frequently 480 used to send spam or participate in DDoS attacks, the ISP 481 servicing those hosts will normally receive complaints about the 482 malicious network traffic. Those complaints may be sent to 483 RFC2142-specified [RFC2142] role accounts, such as abuse@, or to 484 other relevant addresses such as to abuse or security addresses 485 specified by the site as part of its WHOIS (or other) contact 486 data. 488 f. ISPs may also discover likely bot infected hosts located on other 489 networks. Thus, when legally permissible in a particular market 490 region, it may be worthwhile for ISPs to share information 491 relating to those compromised hosts with the relevant remote 492 network operator, with security researchers, and with blocklist 493 operators. 495 g. ISPs may operate or subscribe to services that provide 496 'sinkholing' or 'honeynet' capabilities. This may enable the ISP 497 to obtain near-real-time lists of bot infected hosts as they 498 attempt to join a larger botnet or propagate to other hosts on a 499 network. 501 h. ISP industry associations should examine the possibility of 502 collating statistics from ISP members in order to provide good 503 statistics about bot infections based on real ISP data. 505 i. An Intrusion Detection System(IDS) can be a useful tool to 506 actually identify to help identify the malware. An IDS tool such 507 as SNORT (open source IDS platform) can be placed in a Walled 508 Garden and used to analyze end user traffic to confirm malware 509 type. This will help with remediation of the infected device. 511 6. Notification to Internet Users 513 Once an ISP has detected a bot, or the strong likelihood of a bot, 514 steps should be undertaken to inform the Internet user that they may 515 have a bot-related problem. Depending upon a range of factors, from 516 the technical capabilities of the ISP, to the technical attributes of 517 their network, financial considerations, available server resources, 518 available organizational resources, the number of likely infected 519 hosts detected at any given time, and the severity of any possible 520 threats, among many other things, an ISP should decide the most 521 appropriate method or methods for providing notification to one or 522 more of their customers or Internet users. Such notification methods 523 may include one or more of the following, as well as other possible 524 methods not described below. 526 It is important to note that none of these methods are guaranteed to 527 be one-hundred percent successful, and that each has its own set of 528 limitations. In addition, in some cases, an ISP may determine that a 529 combination of two or more methods is most appropriate and effective, 530 and reduces the chance that malware may block a notification. As 531 such, the authors recommend the use of multiple notification methods. 532 Finally, notification is also considered time sensitive; if the user 533 does not receive or view the notification or a timely basis, then a 534 particular bot could launch an attack, exploit the user, or cause 535 other harm. If possible, an ISP should establish a preferred means 536 of communication when the subscriber first signs up for service. As 537 a part of the notification process, ISPs should maintain a record of 538 the allocation of IP addresses to subscribers for such a period as 539 allows any commonly used bot detection technology to be able to 540 accurately link an infected IP address to a subscriber. This record 541 should only be maintained for a period of time which is necessary, in 542 order to maintain the protection of the privacy of an individual 543 subscriber. 545 One important factor to bear in mind is that notification to end 546 users needs to be resistant to potential spoofing by third parties. 547 This must be done to protect, as reasonably as possible, against the 548 potential of legitimate notifications being spoofed and/or used by 549 parties with malicious intent to perform additional malicious attacks 550 against victims of malware, or even to deliver additional malware. 552 6.1. Email Notification 554 This is a common form of notification used by ISPs. One drawback of 555 using email is that it is not guaranteed to be viewed within a 556 reasonable time frame, if at all. The user may be using a different 557 primary email address than that which they have provided to the ISP. 558 In addition, some ISPs do not provide an email account at all, as 559 part of a bundle of Internet services, and/or do not have a need for 560 or method in which to request or retain the primary email addresses 561 of Internet users of their networks. Another possibility is that the 562 user, their email client, and/or their email servers could determine 563 or classify such a notification as spam, which could delete the 564 message or otherwise file it in an email folder that the user may not 565 check on a regular and/or timely basis. Bot masters have also been 566 known to impersonate the ISP or trusted sender and send fraudulent 567 emails to the users. This technique of social engineering often 568 leads to new bot infestations. Finally if the user's email 569 credentials are compromised, then a hacker and/or a bot could simply 570 login to the user's email account and delete the email before it is 571 read by the user. 573 6.2. Telephone Call Notification 575 A telephone call may be an effective means of communication in 576 particularly high-risk situations. However, telephone calls may not 577 be feasible due to the cost of making a large number of calls, as 578 measured in either time, money, organizational resources, server 579 resources, or some other means. In addition, there is no guarantee 580 that the user will answer their phone. To the extent that the 581 telephone number called by the ISP can be answered by the infected 582 computing device, the bot on that host may be able to disconnect, 583 divert, or otherwise interfere with an incoming call. Users may also 584 interpret such a telephone notification as a telemarketing call and 585 as such not welcome it, or not accept the call at all. Finally, even 586 if a representative of the ISP is able to connect with and speak to a 587 user, that user is very likely to lack the necessary technical 588 expertise to understand or be able to effectively deal with the 589 threat. 591 6.3. Postal Mail Notification 593 This form of notification is probably the least popular and effective 594 means of communication, due to both preparation time, delivery time, 595 the cost of printing and paper, and the cost of postage. 597 6.4. Walled Garden Notification 599 Placing a user in a walled garden is another approach that ISPs may 600 take to notify users. A walled garden refers to an environment that 601 controls the information and services that a subscriber is allowed to 602 utilize and what network access permissions are granted. This is an 603 effective technique because it could be able to block all 604 communication between the bot and the command and control channel, 605 which may impair the ability of a bot to disrupt or block attempts to 606 notify the user. 608 While in many cases the user is almost guaranteed to view the 609 notification message and take any appropriate remediation actions, 610 this approach poses can pose other challenges. For example, it is 611 not always the case that a user is actively using a host that uses a 612 web browser or which has a web browser actively running on it, or 613 that uses another application which uses ports which are redirected 614 to the walled garden. In one example, a user could be playing a game 615 online, via the use of a dedicated, Internet-connected game console. 617 In another example, the user may not be using a host with a web 618 browser when they are placed in the walled garden and may instead be 619 in the course of a telephone conversation, or may be expecting to 620 receive a call, using a Voice Over IP (VoIP) device of some type. As 621 a result, the ISP may feel the need to maintain a potentially lengthy 622 white list of domains which are not subject to the typical 623 restrictions of a walled garden, which could well prove to be an 624 onerous task, from an operational perspective. 626 The ISP has several options to determine when to let the user out of 627 the walled garden. One approach may be to let the user determine 628 when to exit. This option is suggested when the primary purpose of 629 the walled garden is to notify users and provide information on 630 remediation only, particularly since notification is not a guarantee 631 of successful remediation. It could also be the case that, for 632 whatever reason, the user makes the judgment that they cannot then 633 take the time to remediate their host and that other online 634 activities which they would like to resume are more important. Exit 635 from the walled garden may also involve a process to verify that it 636 is indeed the user who is requesting exit from the walled garden and 637 not the bot. 639 Once the user acknowledges the notification, they may decide to 640 either remediate and exit the walled garden or to exit the walled 641 garden without remediating the issue. Another approach may be to 642 enforce a stricter policy and require the user to clean the host 643 prior to permitting the user to exit the walled garden, though this 644 may not be technically feasible depending upon the type of bot, 645 obfuscation techniques employed by a bot, and/or a range of other 646 factors. Thus, the ISP may also need to support tools to scan the 647 infected host (in the style of a virus scan, rather than a port scan) 648 and determine whether it is still infected or rely on user judgment 649 that the bot has been disabled or removed. One challenge with this 650 approach is that if the user has multiple hosts sharing a single IP 651 address, such as via a common home gateway device which performs 652 Network Address Translation (NAT). In such a case, the ISP may need 653 to determine from user feedback, or other means, that all affected 654 hosts have been remediated, which may or may not be technically 655 feasible. 657 Finally, when a walled garden is used, a list of well-known addresses 658 for both operating system vendors and security vendors should be 659 created and maintained in a white list which permits access to these 660 sites. This can be important for allowing access from the walled 661 garden by end users in search of operating system and application 662 patches. 664 6.5. Instant Message Notification 666 Instant messaging provides the ISP with a simple means to communicate 667 with the user. There are several advantages to using IM which makes 668 it an attractive option. If the ISP provides IM service and the user 669 subscribes to it, then the user can be notified easily. IM-based 670 notification can be a cost effective means to communicate with users 671 automatically from an IM alert system or via a manual process, by the 672 ISP's support staff. Ideally, the ISP should allow the user to 673 register their IM identity in an ISP account management system and 674 grant permission to be contacted via this means. If the IM service 675 provider supports off-line messaging, then the user can be notified 676 regardless of whether they are currently logged into the IM system. 678 There are several drawbacks with this communications method. There 679 is a high probability that subscriber may interpret the communication 680 to be spam, and as such ignore it. Also, not every user uses IM 681 and/or the user may not provide their IM identity to the ISP so some 682 alternative means have to be used. Even in those cases where a user 683 does have an IM address, they may not be signed onto that IM system 684 when the notification is attempted. There maybe also be a privacy 685 concern on the part of users, when such an IM notification must be 686 transmitted over a third-party network and/or IM service. As such, 687 should this method be used, the notification should be discreet and 688 not include any PII in the notification itself. 690 6.6. Short Message Service (SMS) Notification 692 SMS allows the ISP send a brief description of the problem to notify 693 the user of the issue, typically to a mobile device such as a mobile 694 phone or smart phone. Ideally, the ISP should allow the user to 695 register their mobile number and/or SMS address in an ISP account 696 management system and grant permission to be contacted via this 697 means. The primary advantage of SMS is that users are familiar with 698 receiving text messages and are likely to read them. However, users 699 may not act on the notification immediately if they are not in front 700 of their host at the time of the SMS notification. 702 One disadvantage is that ISPs may have to follow up with an alternate 703 means of notification if not all of the necessary information maybe 704 conveyed in one message, given constraints on the number of 705 characters in an individual message (typically 140 characters). 706 Another disadvantage with SMS is the cost associated with it. The 707 ISP has to either build its own SMS gateway to interface with the 708 various wireless network service providers or use a third-party SMS 709 clearinghouse (relay) to notify users. In both cases an ISP may 710 incur fees related to SMS notifications, depending upon the method 711 used to send the notifications. An additional downside is that SMS 712 messages sent to a user may result in a charge to the user by their 713 wireless provider, depending upon the plan to which they subscribe. 714 Another minor disadvantage is that it is possible to notify the wrong 715 user if the intended user changes their mobile number but forgets to 716 update it with the ISP. 718 There are several other drawbacks with this communications method. 719 There is a high probability that subscriber may interpret the 720 communication to be spam, and as such ignore it. Also, not every 721 user uses SMS and/or the user may not provide their SMS address or 722 mobile number to the ISP. Even in those cases where a user does have 723 an SMS address or mobile number, their device may not be powered on 724 or otherwise available on a wireless network when the notification is 725 attempted. There maybe also be a privacy concern on the part of 726 users, when such an SMS notification must be transmitted over a 727 third-party network and/or SMS clearinghouse. As such, should this 728 method be used, the notification should be discreet and not include 729 any PII in the notification itself. 731 6.7. Web Browser Notification 733 Near real-time notification to the user's web browser is another 734 technique that may be utilized for notifying the user, though how 735 such a system might operate is outside the scope of this document. 736 Such a notification could have a comparative advantage over a walled 737 garden notification, in that it does not restrict traffic to a 738 specified list of destinations in the same way that a walled garden 739 by definition would. However, as with a walled garden notification, 740 there is no guarantee that a user is at any given time making use of 741 a web browser, though such a system could certainly provide a 742 notification when such a browser is eventually used. Compared to a 743 walled garden, a web browser notification is probably preferred from 744 the perspective of Internet users, as it does not have the risk of 745 disrupting non-web sessions, such as online games, VoIP calls, etc. 746 (as noted in Section 6.4). 748 6.8. Considerations for Notification to Public Network Locations 750 Delivering a notification to a location that provides a shared public 751 network, such as a train station, public square, coffee shop, or 752 similar location may be of low value since the users connecting to 753 such networks are typically highly transient and generally not know 754 to site or network administrators. For example, a system may detect 755 that a host on such a network has a bot, but by the time a 756 notification is generated that user has departed from the network and 757 moved elsewhere. 759 6.9. Considerations for Notification to Network Locations Using a 760 Shared IP Address 762 Delivering a notification to a location that Internet access routed 763 through one or more shared public IP addresses may be of low value 764 since it may be quite difficult to differentiate between users when 765 providing a notification. For example, on a business network of 500 766 users, all sharing one public IP address, it may be sub-optimal to 767 provide a notification to all 500 users if you only need one specific 768 user to be notified and take action. As a result, such networks may 769 find value in establishing a localized bot detection and notification 770 system, just as they are likely to also establish other localized 771 systems for security, file sharing, email, and so on. 773 However, should an ISP implement some form of notification to such 774 networks, it may be better to simply send notifications to a 775 designated network administrator at the site. In such a case the 776 local network administrator may like to receive additional 777 information in such a notification, such as a date and timestamp, the 778 source port of the infected system, and malicious sites that may have 779 been visited. 781 7. Remediation of Hosts Infected with a Bot 783 This section covers the different options available to remediate a 784 host, which means to remove, disable, or otherwise render a bot 785 harmless. Prior to this step, an ISP has detected the bot, notified 786 the user that one of their hosts is infected with a bot, and now may 787 provide some recommended means to clean the host. The generally 788 recommended approach is to provide the necessary tools and education 789 to the user so that they may perform bot remediation themselves, 790 particularly given the risks and difficulties inherent in attempting 791 to remove a bot. 793 For example, this may include the creation of a special web site with 794 security-oriented content that is dedicated for this purpose. This 795 should be a well-publicized security web site to which a user with a 796 bot infection can be directed to for remediation. This security web 797 site should clearly explain why the user was notified and may include 798 an explanation of what bots are, and the threats that they pose. 799 There should be a clear explanation of the steps that the user should 800 take in order to attempt to clean their host and provide information 801 on how users can keep the host free of future infections. The 802 security web site should also have a guided process that takes non- 803 technical users through the remediation process, on an easily 804 understood, step-by-step basis. 806 In terms of the text used to explain what bots are and the threats 807 that they pose, something simple such as this may suffice: 809 "What is a bot? A bot is a piece of software, generally 810 installed on your machine without your knowledge, which either 811 sends spam or tries to steal your personal information. They 812 can be very difficult to spot, though you may have noticed that 813 your computer is running much more slowly than usual or you 814 notice regular disk activity even when you are not doing 815 anything. Ignoring this problem is risky to you and your 816 personal information. Thus, bots need to be removed to protect 817 your data and your personal information." 819 It is also important to note that it may not be immediately apparent 820 to the Internet user precisely which devices have been infected with 821 a particular bot. This may be due to the user's home network 822 configuration, which may encompass several hosts, where a home 823 gateway which performs Network Address Translation (NAT) to share a 824 single public IP address has been used. Therefore, any of these 825 devices can be infected with a bot. The consequence of this for an 826 ISP is that remediation advice may not ultimately be immediately 827 actionable by the Internet user, as that user may need to perform 828 additional investigation within their own home network. 830 An added complication is that the user may have a bot infection on a 831 device such as a video console, multimedia system, appliance, or 832 other end-user computing device which does not have a typical Windows 833 or Macintosh user interface. As a result, diligence needs to be 834 taken by the ISP where possible such that they can identify and 835 communicate the specific nature of the device that has been infected 836 with a bot, and further providing appropriate remediation advice. 838 There are a number of forums that exist online to provide security 839 related support to end users. These forums are staffed by volunteers 840 and often are focussed around the use of a common tool set to help 841 end users to remediate hosts infected with malware. It may be 842 advantageous to ISPs to foster a relationship with one or more 843 forums, perhaps by offering free hosting or other forms of 844 sponsorship. 846 8. Guided Remediation Process 848 Minimally the Guided Remediation Process should include options 849 and/or recommendations on how a user should: 851 1. Backup personal Documents, for example: "Before you start, make 852 sure to back up all of your important data. (You should do this 853 on a regular basis anyway.) You can back up your files manually 854 or using a system back-up software utility, which may be part of 855 your Operating System (OS). You can back your files up to a USB 856 Thumb Drive (aka USB Key), a writeable CD/DVD-ROM, an external 857 hard drive, or a network file server." 859 2. Download OS patches and Anti-Virus (A/V) software updates. For 860 example, links could be provided to Microsoft Windows updates at 861 http://update.microsoft.com/microsoftupdate/v6/ 862 default.aspx?ln=en-us as well as to Apple MacOS updates at 863 http://support.apple.com/kb/HT1338?viewlocale=en_US. 865 3. Explain how to configure the host to automatically install 866 updates for the OS, A/V and other common Web Browsers such as 867 Microsoft Internet Explorer, Mozilla Firefox, Apple Safari, 868 Opera, and Google Chrome. 870 4. The flow should also have the option for users to get 871 professional assistance if they are unable to remove the bots 872 themselves. If purchasing third party assistance, then the user 873 should be encouraged to pre-determine how much they are willing 874 to pay for that help. If the host that is being remediated is 875 old and can easily be replaced with a new, faster, larger and 876 more reliable system for three or four hundred dollars, the it 877 makes no sense to spend five or six hundred dollars to fix the 878 old host, for example. On the other hand, if the customer has a 879 brand new host that cost several thousand dollars, it might make 880 perfect sense to spend the money in attempting to remediate it. 882 5. To continue, regardless of whether the user or a knowledgeable 883 technical assistant is working on remediating the host, their 884 first task should be to determine which of multiple potentially- 885 infected machines may be the one that needs attention (in the 886 common case of multiple hosts in a home network). Sometimes, as 887 in cases where there is only a single directly-attached host, or 888 the user has been noticing problems with one of their hosts, this 889 can be easy. Other times, it may be more difficult. If the user 890 is behind a home gateway/router, then the first task may be to 891 ascertain which of the machines is infected. In some cases the 892 user may have to check all machines to identify the infected one. 894 6. User surveys to solicit feedback on whether the notification and 895 remediation process is effective and what recommended changes 896 could be made in order to improve the ease, understandability, 897 and effectiveness the remediation process. 899 7. If the user is interested in reporting his or her host's bot 900 infection to an applicable law enforcement authority, then the 901 host effectively becomes a cyber "crime scene" and should not be 902 mitigated unless or until law enforcement has collected the 903 necessary evidence. For individuals in this situation, the ISP 904 should refer them to local, state, federal, or other relevant 905 computer crime offices. (Note: Some "minor" incidents, even if 906 highly traumatic to the user, may not be sufficiently serious for 907 law enforcement to commit some of their limited resources to an 908 investigation.) In addition, individual regions may have other, 909 specialized computer crime organizations to which these incidents 910 can be reported. For example, in the United States, that 911 organization is the Internet Crime Complaint Center, at 912 http://www.ic3.gov. 914 8. Users may also be interested in links to security expert forums, 915 where other users can assist them. 917 9. Professionally-Assisted Remediation Process 919 It should be acknowledged that, based on the current state of 920 remediation tools and the technical abilities of end users, that many 921 users may be unable to remediate on their own. As a result, it is 922 recommended that users have the option to avail themselves of 923 professional assistance. This may entail online or telephone 924 assistance for remediation, as well as working face to face with a 925 professional who has training and expertise in the removal of 926 malware. 928 10. Sharing of Data from the User to the ISP 930 As an additional consideration, it may be useful to create a process 931 by which users could choose, at their option and with their express 932 consent, to share data regarding their bot infection with their ISP 933 and/or another authorized third party. Such third parties may 934 include governmental entities that aggregate threat data, such as the 935 Internet Crime Complaint Center referred to earlier in this document, 936 to academic institutions, and/or security researchers. While in many 937 cases the information shared with the user's ISP or designated third 938 parties will only be used for aggregated statistical analysis, it is 939 also possible that certain research needs may be best met with more 940 detailed data. Thus, any such data sharing from a user to the ISP or 941 authorized third party may contain some type of personally 942 identifiable information, either by design or inadvertently. As a 943 result, any such data sharing must be enabled on an opt-in based, 944 where users review and approve of the data being shared and the 945 parties with which it is to be shared, unless the ISP is already 946 required to share such data in order to comply with local laws and in 947 accordance with those laws and applicable regulations. 949 11. Security Considerations 951 This document describes in detail the numerous security risks and 952 concerns relating to bot nets. As such, it has been appropriate to 953 include specific information about security in each section above. 954 This document describes the security risks related to malicious bot 955 infections themselves, such as enabling identity theft, theft of 956 authentication credentials, and the use of a host to unwittingly 957 participate in a DDoS attack, among many other risks. This document 958 also describes at a high level the activities that ISPs should be 959 sensitive to, where the collection or communication of PII may be 960 possible. Finally, the document also describes security risks which 961 may relate to the particular methods of communicating a notification 962 to Internet users. Bot networks and bot infections pose extremely 963 serious security risks and any reader should review this document 964 carefully. 966 In addition, regarding notifications, as described in Section 6, care 967 should be taken to assure users that notifications have been provided 968 by a trustworthy site and/or party, so that the notification is more 969 difficult for phishers and/or malicious parties using social 970 engineering tactics to mimic, or that the user has some level of 971 trust that the notification is valid, and/or that the user has some 972 way to verify via some other mechanism or step that the notification 973 is valid. 975 As noted in Section 10, any sharing of data from the User to the ISP 976 and/or authorized third parties must be done on an opt-in basis and 977 with a clear by the user of the data to be shared and with whom it is 978 to be shared. 980 Lastly, as noted in some other sections, there my be legal 981 requirements in particular legal jurisdictions concerning how long 982 any subscriber-related or other data is retained, of which an ISP 983 operating in such a jurisdiction must be aware and with which an ISP 984 must comply. 986 12. IANA Considerations 988 There are no IANA considerations in this document. 990 13. Acknowledgements 992 The authors wish to acknowledge the following individuals for 993 performing a detailed review of this document and/or providing 994 comments and feedback with had helped to improve and evolve this 995 document: 997 Mark Baugher 999 Richard Bennett 1001 James Butler 1003 Vint Cerf 1005 Alissa Cooper 1007 Jonathan Curtis 1009 Jeff Chan 1011 Roland Dobbins 1013 Dave Farber 1015 Eliot Gillum 1017 Joel Halpern 1019 Joel Jaeggli 1021 Scott Keoseyan 1023 The Messaging Anti-Abuse Working Group (MAAWG) 1025 Jose Nazario 1027 Gunter Ollmann 1029 David Reed 1031 Roger Safian 1033 Donald Smith 1035 Joe Stewart 1037 Forrest Swick 1038 Robb Topolski 1040 Eric Ziegast 1042 14. Informative references 1044 [Battling Botnets and Online Mobs: Estonia's Defense Efforts during 1045 the Internet War] 1046 Evron, G., "Battling Botnets and Online Mobs: Estonia's 1047 Defense Efforts during the Internet War", May 2005, . 1053 [Case Study: How a Bookmaker and a Whiz Kid Took On a DDOS-based 1054 Online Extortion Attack] 1055 Berinato, S., "Case Study: How a Bookmaker and a Whiz Kid 1056 Took On a DDOS-based Online Extortion Attack", May 2005, < 1057 http://www.csoonline.com/article/220336/ 1058 How_a_Bookmaker_and_a_Whiz_Kid_Took_On_a_DDOS_based_Online 1059 _Extortion_Attack>. 1061 [Cyberspace as a Combat Zone: The Phenomenon of Electronic Jihad] 1062 Alshech, E., "Cyberspace as a Combat Zone: The Phenomenon 1063 of Electronic Jihad", February 2007, . 1066 [Distributed Denial of Service Attacks: Explanation, Classification 1067 and Suggested Solutions] 1068 Saafan, A., "Distributed Denial of Service Attacks: 1069 Explanation, Classification and Suggested Solutions", 1070 March 2009, . 1074 [Emerging Cyber Threats Report for 2009: Data, Mobility and Questions 1075 of Responsibility will Drive Cyber Threats in 2009 and Beyond] 1076 Ahamad, M., Amster, D., Barret, M., Cross, T., Heron, G., 1077 Jackson, D., King, J., Lee, W., Naraine, R., Ollman, G., 1078 Ramsey, J., Schmidt, H., and P. Traynor, "Emerging Cyber 1079 Threats Report for 2009: Data, Mobility and Questions of 1080 Responsibility will Drive Cyber Threats in 2009 and 1081 Beyond", October 2008, . 1084 [Persistent Memory Infection] 1085 Sacco, A. and A. Ortega, "Persistent BIOS Infection", 1086 March 2009, . 1089 [RFC1459] Oikarinen, J. and D. Reed, "Internet Relay Chat Protocol", 1090 RFC 1459, May 1993. 1092 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1093 Requirement Levels", BCP 14, RFC 2119, March 1997. 1095 [RFC2142] Crocker, D., "MAILBOX NAMES FOR COMMON SERVICES, ROLES AND 1096 FUNCTIONS", RFC 2142, May 1997. 1098 [RFC3954] Claise, B., "Cisco Systems NetFlow Services Export Version 1099 9", RFC 3954, October 2004. 1101 [Spamalytics: An Empirical Analysis of Spam Marketing Conversion] 1102 Kanich, C., Kreibich, C., Levchenko, K., Enright, B., 1103 Voelker, G., Paxson, V., and S. Savage, "Spamalytics: An 1104 Empirical Analysis of Spam Marketing Conversion", 1105 October 2008, . 1108 [The Gh0st in the Shell: Network Security in the Himalayas] 1109 Vallentin, M., Whiteaker, J., and Y. Ben-David, "The Gh0st 1110 in the Shell: Network Security in the Himalayas", 1111 February 2010, . 1114 [The snooping dragon: social-malware surveillance of the Tibetan 1115 movement] 1116 Nagaraja, S. and R. Anderson, "The snooping dragon: 1117 social-malware surveillance of the Tibetan movement", 1118 March 2009, 1119 . 1121 Appendix A. Document Change Log 1123 [RFC Editor: This section is to be removed before publication] 1125 -08 version: 1127 o Corrected a reference error in Section 10. 1129 o Added a new informative reference 1130 o Change to Section 5.a., to note additional port scanning 1131 limitations 1133 o Per Joel Jaeggli, change computer to host, to conform to IETF 1134 document norms 1136 o Several other changes suggested by Joel Jaeggli and Donald Smith 1137 on the OPSEC mailing list 1139 o Incorp. other feedback received privately 1141 o Because Jason is so very dedicated, he worked on this revision 1142 while on vacation ;-) 1144 -07 version: 1146 o Corrected various spelling and grammatical errors, pointed out by 1147 additional reviewers. Also added a section on information flowing 1148 from the user. Lastly, updated the reviewer list to include all 1149 those who either were kind enough to review for us or who provided 1150 interesting, insightful, and/or helpful feedback. 1152 -06 version: 1154 o Corrected an error in the version change log, and added some extra 1155 information on user remediation. Also added an informational 1156 reference to BIOS infection. 1158 -05 version: 1160 o Minor tweaks made by Jason - ready for wider review and next 1161 steps. Also cleared open issues. Lastly, added 2nd paragraph to 1162 security section and added sections on limitations relating to 1163 public and other shared network sites. Added a new section on 1164 professional remediation. 1166 -04 version: 1168 o Updated reference to BIOS based malware, added wording on PII and 1169 local jurisdictions, added suggestion that industry body produce 1170 bot stats, added suggestion that ISPs use volunteer forums 1172 -03 version: 1174 o all updates from Jason - now ready for wider external review 1176 -02 version: 1178 o all updates from Jason - still some open issues but we're now at a 1179 place where we can solicit more external feedback 1181 -01 version: 1183 o -01 version published 1185 Appendix B. Open Issues 1187 [RFC Editor: This section is to be removed before publication] 1189 per Donald, in notification method section, consider taking this text 1190 from the phone method and using as a new section with drawbacks/ 1191 challenges: Finally, even if a representative of the ISP is able to 1192 connect with and speak to a user, that user is very likely to lack 1193 the necessary technical expertise to understand or be able to 1194 effectively deal with the threat. 1196 per Donald, consider w/r/t the WG method: That is really the 1197 definition of a quarantine walled garden. Walled garden's don't have 1198 to quarantine the user (much) to notify the customer. They can be 1199 fairly leaky and still notify the customer of their infection. 1201 per Donald, consider text re users who continue to fail to mitigate: 1202 Another good approach is just to keep track of whom was put into the 1203 walled garden for which infection and if they keep showing up as 1204 infected via the trusted third party reports then you can assume they 1205 are unable/unwilling to remediate and take what ever additional 1206 actions you deem appropriate. 1208 per Donald, inclusion of PII is a good general stmt to consider for 1209 an opening section in the notification part of the doc: As such, 1210 should this method be used, the notification should be discreet and 1211 not include any PII in the notification itself. 1213 per Donald, do we want to consider adding a 'leaky' WG? 'Or design a 1214 leaky walled garden that allows most traffic without interference 1215 only redirecting the traffic needed to mitigate or notify.' 1217 search for and remove double spaces 1219 Address suggestion from Donald Smith: The risks to users of infected 1220 systems and others are included/defined in many places within this 1221 document. It should probably be defined clearly in one place and 1222 referenced in all other places. 1224 per Roger - ponder acct termination 1225 A question has been raised about whether this should change from 1226 Informational to BCP. 1228 Guided remediation -- these urls while provided for the purpose of 1229 examples are unlikely to be stable on any kind of long timescale. 1230 fundamentally updating os software addresses vulnerability not 1231 remediation (windows malicious software removal tool notwithstanding) 1233 Guided remediation, bullets 4 - 7 -- It's unclear how these steps are 1234 even feasible to undertake for organizations nominally characterized 1235 as ISPs. there's a several thousand fold cost differential between 1236 automated help and remediation by sending a train professional to lay 1237 hands on one computer. 1239 Authors' Addresses 1241 Jason Livingood 1242 Comcast Cable Communications 1243 One Comcast Center 1244 1701 John F. Kennedy Boulevard 1245 Philadelphia, PA 19103 1246 US 1248 Email: jason_livingood@cable.comcast.com 1249 URI: http://www.comcast.com 1251 Nirmal Mody 1252 Comcast Cable Communications 1253 One Comcast Center 1254 1701 John F. Kennedy Boulevard 1255 Philadelphia, PA 19103 1256 US 1258 Email: nirmal_mody@cable.comcast.com 1259 URI: http://www.comcast.com 1260 Mike O'Reirdan 1261 Comcast Cable Communications 1262 One Comcast Center 1263 1701 John F. Kennedy Boulevard 1264 Philadelphia, PA 19103 1265 US 1267 Email: michael_oreirdan@cable.comcast.com 1268 URI: http://www.comcast.com