Annotation of www/security.html, Revision 1.441
1.441 ! bentley 1: <!doctype html>
! 2: <html lang=en>
! 3: <meta charset=utf-8>
! 4:
1.430 tj 5: <title>OpenBSD: Security</title>
1.425 deraadt 6: <meta name="viewport" content="width=device-width, initial-scale=1">
7: <link rel="stylesheet" type="text/css" href="openbsd.css">
1.432 tb 8: <link rel="canonical" href="https://www.openbsd.org/security.html">
1.1 deraadt 9:
1.441 ! bentley 10: <style>
! 11: h3 {
! 12: color: var(--red);
! 13: }
! 14: </style>
1.428 tb 15:
1.441 ! bentley 16: <h2 id=OpenBSD>
1.425 deraadt 17: <a href="index.html">
1.441 ! bentley 18: <i>Open</i><b>BSD</b></a>
! 19: Security
1.427 tb 20: </h2>
1.441 ! bentley 21:
1.294 david 22: <hr>
1.441 ! bentley 23:
1.429 tj 24: <p>
1.441 ! bentley 25: For security advisories for specific releases, click below:
1.1 deraadt 26:
1.294 david 27: <p>
1.406 deraadt 28:
1.418 tedu 29: <a href="errata21.html">2.1</a>,
30: <a href="errata22.html">2.2</a>,
31: <a href="errata23.html">2.3</a>,
32: <a href="errata24.html">2.4</a>,
33: <a href="errata25.html">2.5</a>,
34: <a href="errata26.html">2.6</a>,
35: <a href="errata27.html">2.7</a>,
36: <a href="errata28.html">2.8</a>,
37: <a href="errata29.html">2.9</a>,
38: <a href="errata30.html">3.0</a>,
39: <a href="errata31.html">3.1</a>,
40: <a href="errata32.html">3.2</a>,
41: <a href="errata33.html">3.3</a>,
42: <a href="errata34.html">3.4</a>,
43: <a href="errata35.html">3.5</a>,
44: <a href="errata36.html">3.6</a>,
1.420 schwarze 45: <a href="errata37.html">3.7</a>,
1.365 deraadt 46: <br>
1.418 tedu 47: <a href="errata38.html">3.8</a>,
48: <a href="errata39.html">3.9</a>,
49: <a href="errata40.html">4.0</a>,
50: <a href="errata41.html">4.1</a>,
51: <a href="errata42.html">4.2</a>,
52: <a href="errata43.html">4.3</a>,
53: <a href="errata44.html">4.4</a>,
54: <a href="errata45.html">4.5</a>,
55: <a href="errata46.html">4.6</a>,
56: <a href="errata47.html">4.7</a>,
57: <a href="errata48.html">4.8</a>,
58: <a href="errata49.html">4.9</a>,
59: <a href="errata50.html">5.0</a>,
60: <a href="errata51.html">5.1</a>,
61: <a href="errata52.html">5.2</a>,
62: <a href="errata53.html">5.3</a>,
1.420 schwarze 63: <a href="errata54.html">5.4</a>,
1.406 deraadt 64: <br>
1.419 jsg 65: <a href="errata55.html">5.5</a>,
1.420 schwarze 66: <a href="errata56.html">5.6</a>,
1.423 benno 67: <a href="errata57.html">5.7</a>,
1.431 deraadt 68: <a href="errata58.html">5.8</a>,
69: <a href="errata59.html">5.9</a>,
1.434 tj 70: <a href="errata60.html">6.0</a>,
1.435 deraadt 71: <a href="errata61.html">6.1</a>,
1.436 deraadt 72: <a href="errata62.html">6.2</a>,
1.437 deraadt 73: <a href="errata63.html">6.3</a>,
1.440 deraadt 74: <a href="errata64.html">6.4</a>,
75: <a href="errata65.html">6.5</a>.
1.406 deraadt 76: <br>
1.56 deraadt 77: <hr>
78:
1.278 deraadt 79: <ul>
1.441 ! bentley 80: <li><h3 id=goals>Goals</h3>
1.22 deraadt 81:
1.441 ! bentley 82: <p>
1.14 deraadt 83: OpenBSD believes in strong security. Our aspiration is to be NUMBER
1.22 deraadt 84: ONE in the industry for security (if we are not already there). Our
85: open software development model permits us to take a more
1.424 tb 86: uncompromising view towards increased security than most vendors are
87: able to. We can make changes the vendors would
1.27 deraadt 88: not make. Also, since OpenBSD is exported with <a href=crypto.html>
1.45 deraadt 89: cryptography</a>, we are able to take cryptographic approaches towards
1.441 ! bentley 90: fixing security problems.
1.18 deraadt 91:
1.441 ! bentley 92: <li><h3 id=disclosure>Full Disclosure</h3>
1.106 deraadt 93:
1.441 ! bentley 94: <p>
1.45 deraadt 95: Like many readers of the
1.438 tb 96: <a href="https://www.securityfocus.com/archive/1">
1.18 deraadt 97: BUGTRAQ mailing list</a>,
1.106 deraadt 98: we believe in full disclosure of security problems. In the
99: operating system arena, we were probably the first to embrace
100: the concept. Many vendors, even of free software, still try
1.441 ! bentley 101: to hide issues from their users.
1.106 deraadt 102:
1.441 ! bentley 103: <p>
1.106 deraadt 104: Security information moves very fast in cracker circles. On the other
105: hand, our experience is that coding and releasing of proper security
1.441 ! bentley 106: fixes typically requires about an hour of work — very fast fix
1.106 deraadt 107: turnaround is possible. Thus we think that full disclosure helps the
108: people who really care about security.<p>
109:
1.441 ! bentley 110: <li><h3 id=process>Audit Process</h3>
1.15 deraadt 111:
1.441 ! bentley 112: <p>
1.12 deraadt 113: Our security auditing team typically has between six and twelve
1.45 deraadt 114: members who continue to search for and fix new security holes. We
115: have been auditing since the summer of 1996. The process we follow to
116: increase security is simply a comprehensive file-by-file analysis of
1.106 deraadt 117: every critical software component. We are not so much looking for
118: security holes, as we are looking for basic software bugs, and if
1.138 deraadt 119: years later someone discovers the problem used to be a security
1.106 deraadt 120: issue, and we fixed it because it was just a bug, well, all the
121: better. Flaws have been found in just about every area of the system.
122: Entire new classes of security problems have been found during our
123: audit, and often source code which had been audited earlier needs
124: re-auditing with these new flaws in mind. Code often gets audited
125: multiple times, and by multiple people with different auditing
1.441 ! bentley 126: skills.
1.12 deraadt 127:
1.441 ! bentley 128: <p>
1.94 deraadt 129: Some members of our security auditing team worked for Secure Networks,
130: the company that made the industry's premier network security scanning
131: software package Ballista (Secure Networks got purchased by Network
132: Associates, Ballista got renamed to Cybercop Scanner, and well...)
133: That company did a lot of security research, and thus fit in well
1.106 deraadt 134: with the OpenBSD stance. OpenBSD passed Ballista's tests with flying
1.441 ! bentley 135: colours since day 1.
1.31 deraadt 136:
1.441 ! bentley 137: <p>
1.34 deraadt 138: Another facet of our security auditing process is its proactiveness.
1.45 deraadt 139: In most cases we have found that the determination of exploitability
140: is not an issue. During our ongoing auditing process we find many
141: bugs, and endeavor to fix them even though exploitability is not
142: proven. We fix the bug, and we move on to find other bugs to fix. We
143: have fixed many simple and obvious careless programming errors in code
144: and only months later discovered that the problems were in fact
145: exploitable. (Or, more likely someone on
1.439 tb 146: <a href="https://www.securityfocus.com/archive/1">BUGTRAQ</a>
1.441 ! bentley 147: would report that other operating systems were vulnerable to a <q>newly
! 148: discovered problem</q>, and then it would be discovered that OpenBSD had
1.45 deraadt 149: been fixed in a previous release). In other cases we have been saved
150: from full exploitability of complex step-by-step attacks because we
151: had fixed one of the intermediate steps. An example of where we
1.94 deraadt 152: managed such a success is the lpd advisory that Secure Networks put out.
1.29 deraadt 153:
1.441 ! bentley 154: <li><h3 id=newtech>New Technologies</h3>
1.278 deraadt 155:
1.441 ! bentley 156: <p>
1.278 deraadt 157: As we audit source code, we often invent new ways of solving problems.
158: Sometimes these ideas have been used before in some random application
159: written somewhere, but perhaps not taken to the degree that we do.
160:
161: <ul>
162: <li>strlcpy() and strlcat()
163: <li>Memory protection purify
164: <ul>
165: <li>W^X
166: <li>.rodata segment
167: <li>Guard pages
168: <li>Randomized malloc()
169: <li>Randomized mmap()
170: <li>atexit() and stdio protection
171: </ul>
1.295 otto 172: <li>Privilege separation
1.278 deraadt 173: <li>Privilege revocation
174: <li>Chroot jailing
175: <li>New uids
176: <li>ProPolice
1.424 tb 177: <li>... <a href="/innovations.html">and others</a>
1.278 deraadt 178: </ul>
179:
1.441 ! bentley 180: <li><h3 id=reward>The Reward</h3>
1.106 deraadt 181:
1.441 ! bentley 182: <p>
1.45 deraadt 183: Our proactive auditing process has really paid off. Statements like
1.441 ! bentley 184: <q>This problem was fixed in OpenBSD about 6 months ago</q> have become
1.45 deraadt 185: commonplace in security forums like
1.441 ! bentley 186: <a href="https://www.securityfocus.com/archive/1">BUGTRAQ</a>.
1.35 deraadt 187:
1.441 ! bentley 188: <p>
1.45 deraadt 189: The most intense part of our security auditing happened immediately
1.441 ! bentley 190: before the OpenBSD 2.0 release and during the 2.0→2.1 transition,
1.45 deraadt 191: over the last third of 1996 and first half of 1997. Thousands (yes,
192: thousands) of security issues were fixed rapidly over this year-long
193: period; bugs like the standard buffer overflows, protocol
194: implementation weaknesses, information gathering, and filesystem
195: races. Hence most of the security problems that we encountered were
196: fixed before our 2.1 release, and then a far smaller number needed
197: fixing for our 2.2 release. We do not find as many problems anymore,
198: it is simply a case of diminishing returns. Recently the security
199: problems we find and fix tend to be significantly more obscure or
1.441 ! bentley 200: complicated. Still we will persist for a number of reasons:
1.36 deraadt 201:
1.35 deraadt 202: <ul>
1.45 deraadt 203: <li>Occasionally we find a simple problem we missed earlier. Doh!
1.35 deraadt 204: <li>Security is like an arms race; the best attackers will continue
1.45 deraadt 205: to search for more complicated exploits, so we will too.
206: <li>Finding and fixing subtle flaws in complicated software is
207: a lot of fun.
1.35 deraadt 208: </ul>
1.441 ! bentley 209:
1.106 deraadt 210: <p>
1.14 deraadt 211: The auditing process is not over yet, and as you can see we continue
1.441 ! bentley 212: to find and fix new security flaws.
1.12 deraadt 213:
1.441 ! bentley 214: <li><h3 id=default><q>Secure by Default</q></h3>
1.106 deraadt 215:
1.441 ! bentley 216: <p>
1.106 deraadt 217: To ensure that novice users of OpenBSD do not need to become security
218: experts overnight (a viewpoint which other vendors seem to have), we
219: ship the operating system in a Secure by Default mode. All non-essential
220: services are disabled. As the user/administrator becomes more familiar
221: with the system, he will discover that he has to enable daemons and other
222: parts of the system. During the process of learning how to enable a new
1.441 ! bentley 223: service, the novice is more likely to learn of security considerations.
1.106 deraadt 224:
1.441 ! bentley 225: <p>
1.106 deraadt 226: This is in stark contrast to the increasing number of systems that
227: ship with NFS, mountd, web servers, and various other services enabled
228: by default, creating instantaneous security problems for their users
1.441 ! bentley 229: within minutes after their first install.
1.106 deraadt 230:
1.441 ! bentley 231: <li><h3 id=crypto>Cryptography</h3>
1.106 deraadt 232:
1.441 ! bentley 233: <p>
1.106 deraadt 234: And of course, since the OpenBSD project is based in Canada, it is possible
235: for us to integrate cryptography. For more information, read the page
1.441 ! bentley 236: outlining <a href=crypto.html>what we have done with cryptography</a>.
1.106 deraadt 237:
1.441 ! bentley 238: <li><h3 id=advisories>Advisories</h3>
1.106 deraadt 239:
1.441 ! bentley 240: <p>
1.418 tedu 241: Please refer to the links at the top of this page.
1.106 deraadt 242:
1.441 ! bentley 243: <li><h3 id=watching>Watching our Changes</h3>
1.106 deraadt 244:
1.441 ! bentley 245: <p>
1.21 deraadt 246: Since we take a proactive stance with security, we are continually
247: finding and fixing new security problems. Not all of these problems
1.80 espie 248: get widely reported because (as stated earlier) many of them are not
1.45 deraadt 249: confirmed to be exploitable; many simple bugs we fix do turn out to
250: have security consequences we could not predict. We do not have the
1.441 ! bentley 251: time resources to make these changes available in the above format.
1.21 deraadt 252:
1.441 ! bentley 253: <p>
1.21 deraadt 254: Thus there are usually minor security fixes in the current source code
255: beyond the previous major OpenBSD release. We make a limited
1.45 deraadt 256: guarantee that these problems are of minimal impact and unproven
1.44 ian 257: exploitability. If we discover that a problem definitely matters for
1.441 ! bentley 258: security, patches will show up here <strong>VERY</strong> quickly.
1.21 deraadt 259:
1.441 ! bentley 260: <p>
1.45 deraadt 261: People who are really concerned with security can do a number of
1.441 ! bentley 262: things:
1.21 deraadt 263:
264: <ul>
265: <li>If you understand security issues, watch our
1.294 david 266: <a href="mail.html">source-changes mailing list</a> and keep an
1.23 deraadt 267: eye out for things which appear security related. Since
1.21 deraadt 268: exploitability is not proven for many of the fixes we make,
1.441 ! bentley 269: do not expect the relevant commit message to say <q>SECURITY FIX!</q>.
1.21 deraadt 270: If a problem is proven and serious, a patch will be available
271: here very shortly after.
272: <li>Track our current source code tree, and teach yourself how to do a
1.29 deraadt 273: complete system build from time to time (read /usr/src/Makefile
274: carefully). Users can make the assumption that the current
275: source tree always has stronger security than the previous release.
1.45 deraadt 276: However, building your own system from source code is not trivial;
1.424 tb 277: it is over 850MB of source code, and problems do occur as we
1.45 deraadt 278: transition between major releases.
1.115 ericj 279: <li>Install a binary snapshot for your
1.80 espie 280: architecture, which are made available fairly often. For
1.424 tb 281: instance, an amd64 snapshot is typically made available daily.
1.21 deraadt 282: </ul>
283:
1.441 ! bentley 284: <li><h3 id=reporting>Reporting problems</h3>
! 285:
1.9 deraadt 286: <p>
1.441 ! bentley 287: If you find a new security problem, you can mail it to
1.294 david 288: <a href="mailto:deraadt@openbsd.org">deraadt@openbsd.org</a>.
1.7 deraadt 289: <br>
1.5 deraadt 290: If you wish to PGP encode it (but please only do so if privacy is very
1.112 philen 291: urgent, since it is inconvenient) use this <a href="advisories/pgpkey.txt">pgp key</a>.
1.5 deraadt 292:
1.441 ! bentley 293: <li><h3 id=papers>Further Reading</h3>
! 294:
1.107 deraadt 295: <p>
1.389 lum 296: Numerous
1.441 ! bentley 297: <a href="events.html">papers</a> have been written by OpenBSD team members,
1.389 lum 298: many dedicated to security.
1.294 david 299: </ul>
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