Annotation of www/security.html, Revision 1.443
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1.430 tj 5: <title>OpenBSD: Security</title>
1.425 deraadt 6: <meta name="viewport" content="width=device-width, initial-scale=1">
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1.432 tb 8: <link rel="canonical" href="https://www.openbsd.org/security.html">
1.1 deraadt 9:
1.441 bentley 10: <style>
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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>,
1.443 ! deraadt 75: <a href="errata65.html">6.5</a>,
! 76: <a href="errata66.html">6.6</a>.
1.406 deraadt 77: <br>
1.56 deraadt 78: <hr>
79:
1.278 deraadt 80: <ul>
1.441 bentley 81: <li><h3 id=goals>Goals</h3>
1.22 deraadt 82:
1.441 bentley 83: <p>
1.14 deraadt 84: OpenBSD believes in strong security. Our aspiration is to be NUMBER
1.22 deraadt 85: ONE in the industry for security (if we are not already there). Our
86: open software development model permits us to take a more
1.442 deraadt 87: uncompromising view towards increased security than most vendors are
1.424 tb 88: able to. We can make changes the vendors would
1.27 deraadt 89: not make. Also, since OpenBSD is exported with <a href=crypto.html>
1.45 deraadt 90: cryptography</a>, we are able to take cryptographic approaches towards
1.441 bentley 91: fixing security problems.
1.18 deraadt 92:
1.441 bentley 93: <li><h3 id=disclosure>Full Disclosure</h3>
1.106 deraadt 94:
1.441 bentley 95: <p>
1.45 deraadt 96: Like many readers of the
1.438 tb 97: <a href="https://www.securityfocus.com/archive/1">
1.18 deraadt 98: BUGTRAQ mailing list</a>,
1.106 deraadt 99: we believe in full disclosure of security problems. In the
100: operating system arena, we were probably the first to embrace
101: the concept. Many vendors, even of free software, still try
1.441 bentley 102: to hide issues from their users.
1.106 deraadt 103:
1.441 bentley 104: <p>
1.106 deraadt 105: Security information moves very fast in cracker circles. On the other
106: hand, our experience is that coding and releasing of proper security
1.441 bentley 107: fixes typically requires about an hour of work — very fast fix
1.106 deraadt 108: turnaround is possible. Thus we think that full disclosure helps the
109: people who really care about security.<p>
110:
1.441 bentley 111: <li><h3 id=process>Audit Process</h3>
1.15 deraadt 112:
1.441 bentley 113: <p>
1.12 deraadt 114: Our security auditing team typically has between six and twelve
1.45 deraadt 115: members who continue to search for and fix new security holes. We
116: have been auditing since the summer of 1996. The process we follow to
117: increase security is simply a comprehensive file-by-file analysis of
1.106 deraadt 118: every critical software component. We are not so much looking for
119: security holes, as we are looking for basic software bugs, and if
1.138 deraadt 120: years later someone discovers the problem used to be a security
1.106 deraadt 121: issue, and we fixed it because it was just a bug, well, all the
122: better. Flaws have been found in just about every area of the system.
123: Entire new classes of security problems have been found during our
124: audit, and often source code which had been audited earlier needs
125: re-auditing with these new flaws in mind. Code often gets audited
126: multiple times, and by multiple people with different auditing
1.441 bentley 127: skills.
1.12 deraadt 128:
1.441 bentley 129: <p>
1.94 deraadt 130: Some members of our security auditing team worked for Secure Networks,
131: the company that made the industry's premier network security scanning
132: software package Ballista (Secure Networks got purchased by Network
133: Associates, Ballista got renamed to Cybercop Scanner, and well...)
134: That company did a lot of security research, and thus fit in well
1.106 deraadt 135: with the OpenBSD stance. OpenBSD passed Ballista's tests with flying
1.441 bentley 136: colours since day 1.
1.31 deraadt 137:
1.441 bentley 138: <p>
1.34 deraadt 139: Another facet of our security auditing process is its proactiveness.
1.45 deraadt 140: In most cases we have found that the determination of exploitability
141: is not an issue. During our ongoing auditing process we find many
142: bugs, and endeavor to fix them even though exploitability is not
143: proven. We fix the bug, and we move on to find other bugs to fix. We
144: have fixed many simple and obvious careless programming errors in code
145: and only months later discovered that the problems were in fact
146: exploitable. (Or, more likely someone on
1.439 tb 147: <a href="https://www.securityfocus.com/archive/1">BUGTRAQ</a>
1.441 bentley 148: would report that other operating systems were vulnerable to a <q>newly
149: discovered problem</q>, and then it would be discovered that OpenBSD had
1.45 deraadt 150: been fixed in a previous release). In other cases we have been saved
151: from full exploitability of complex step-by-step attacks because we
152: had fixed one of the intermediate steps. An example of where we
1.94 deraadt 153: managed such a success is the lpd advisory that Secure Networks put out.
1.29 deraadt 154:
1.441 bentley 155: <li><h3 id=newtech>New Technologies</h3>
1.278 deraadt 156:
1.441 bentley 157: <p>
1.278 deraadt 158: As we audit source code, we often invent new ways of solving problems.
159: Sometimes these ideas have been used before in some random application
160: written somewhere, but perhaps not taken to the degree that we do.
161:
162: <ul>
163: <li>strlcpy() and strlcat()
164: <li>Memory protection purify
165: <ul>
166: <li>W^X
167: <li>.rodata segment
168: <li>Guard pages
169: <li>Randomized malloc()
170: <li>Randomized mmap()
171: <li>atexit() and stdio protection
172: </ul>
1.295 otto 173: <li>Privilege separation
1.278 deraadt 174: <li>Privilege revocation
175: <li>Chroot jailing
176: <li>New uids
177: <li>ProPolice
1.424 tb 178: <li>... <a href="/innovations.html">and others</a>
1.278 deraadt 179: </ul>
180:
1.441 bentley 181: <li><h3 id=reward>The Reward</h3>
1.106 deraadt 182:
1.441 bentley 183: <p>
1.45 deraadt 184: Our proactive auditing process has really paid off. Statements like
1.441 bentley 185: <q>This problem was fixed in OpenBSD about 6 months ago</q> have become
1.45 deraadt 186: commonplace in security forums like
1.441 bentley 187: <a href="https://www.securityfocus.com/archive/1">BUGTRAQ</a>.
1.35 deraadt 188:
1.441 bentley 189: <p>
1.45 deraadt 190: The most intense part of our security auditing happened immediately
1.441 bentley 191: before the OpenBSD 2.0 release and during the 2.0→2.1 transition,
1.45 deraadt 192: over the last third of 1996 and first half of 1997. Thousands (yes,
193: thousands) of security issues were fixed rapidly over this year-long
194: period; bugs like the standard buffer overflows, protocol
195: implementation weaknesses, information gathering, and filesystem
196: races. Hence most of the security problems that we encountered were
197: fixed before our 2.1 release, and then a far smaller number needed
198: fixing for our 2.2 release. We do not find as many problems anymore,
199: it is simply a case of diminishing returns. Recently the security
200: problems we find and fix tend to be significantly more obscure or
1.441 bentley 201: complicated. Still we will persist for a number of reasons:
1.36 deraadt 202:
1.35 deraadt 203: <ul>
1.45 deraadt 204: <li>Occasionally we find a simple problem we missed earlier. Doh!
1.35 deraadt 205: <li>Security is like an arms race; the best attackers will continue
1.45 deraadt 206: to search for more complicated exploits, so we will too.
207: <li>Finding and fixing subtle flaws in complicated software is
208: a lot of fun.
1.35 deraadt 209: </ul>
1.441 bentley 210:
1.106 deraadt 211: <p>
1.14 deraadt 212: The auditing process is not over yet, and as you can see we continue
1.441 bentley 213: to find and fix new security flaws.
1.12 deraadt 214:
1.441 bentley 215: <li><h3 id=default><q>Secure by Default</q></h3>
1.106 deraadt 216:
1.441 bentley 217: <p>
1.106 deraadt 218: To ensure that novice users of OpenBSD do not need to become security
219: experts overnight (a viewpoint which other vendors seem to have), we
220: ship the operating system in a Secure by Default mode. All non-essential
221: services are disabled. As the user/administrator becomes more familiar
222: with the system, he will discover that he has to enable daemons and other
223: parts of the system. During the process of learning how to enable a new
1.441 bentley 224: service, the novice is more likely to learn of security considerations.
1.106 deraadt 225:
1.441 bentley 226: <p>
1.106 deraadt 227: This is in stark contrast to the increasing number of systems that
228: ship with NFS, mountd, web servers, and various other services enabled
229: by default, creating instantaneous security problems for their users
1.441 bentley 230: within minutes after their first install.
1.106 deraadt 231:
1.441 bentley 232: <li><h3 id=crypto>Cryptography</h3>
1.106 deraadt 233:
1.441 bentley 234: <p>
1.106 deraadt 235: And of course, since the OpenBSD project is based in Canada, it is possible
236: for us to integrate cryptography. For more information, read the page
1.441 bentley 237: outlining <a href=crypto.html>what we have done with cryptography</a>.
1.106 deraadt 238:
1.441 bentley 239: <li><h3 id=advisories>Advisories</h3>
1.106 deraadt 240:
1.441 bentley 241: <p>
1.418 tedu 242: Please refer to the links at the top of this page.
1.106 deraadt 243:
1.441 bentley 244: <li><h3 id=watching>Watching our Changes</h3>
1.106 deraadt 245:
1.441 bentley 246: <p>
1.21 deraadt 247: Since we take a proactive stance with security, we are continually
248: finding and fixing new security problems. Not all of these problems
1.80 espie 249: get widely reported because (as stated earlier) many of them are not
1.45 deraadt 250: confirmed to be exploitable; many simple bugs we fix do turn out to
251: have security consequences we could not predict. We do not have the
1.441 bentley 252: time resources to make these changes available in the above format.
1.21 deraadt 253:
1.441 bentley 254: <p>
1.21 deraadt 255: Thus there are usually minor security fixes in the current source code
256: beyond the previous major OpenBSD release. We make a limited
1.45 deraadt 257: guarantee that these problems are of minimal impact and unproven
1.44 ian 258: exploitability. If we discover that a problem definitely matters for
1.441 bentley 259: security, patches will show up here <strong>VERY</strong> quickly.
1.21 deraadt 260:
1.441 bentley 261: <p>
1.45 deraadt 262: People who are really concerned with security can do a number of
1.441 bentley 263: things:
1.21 deraadt 264:
265: <ul>
266: <li>If you understand security issues, watch our
1.294 david 267: <a href="mail.html">source-changes mailing list</a> and keep an
1.23 deraadt 268: eye out for things which appear security related. Since
1.21 deraadt 269: exploitability is not proven for many of the fixes we make,
1.441 bentley 270: do not expect the relevant commit message to say <q>SECURITY FIX!</q>.
1.21 deraadt 271: If a problem is proven and serious, a patch will be available
272: here very shortly after.
273: <li>Track our current source code tree, and teach yourself how to do a
1.29 deraadt 274: complete system build from time to time (read /usr/src/Makefile
275: carefully). Users can make the assumption that the current
276: source tree always has stronger security than the previous release.
1.45 deraadt 277: However, building your own system from source code is not trivial;
1.424 tb 278: it is over 850MB of source code, and problems do occur as we
1.45 deraadt 279: transition between major releases.
1.115 ericj 280: <li>Install a binary snapshot for your
1.80 espie 281: architecture, which are made available fairly often. For
1.424 tb 282: instance, an amd64 snapshot is typically made available daily.
1.21 deraadt 283: </ul>
284:
1.441 bentley 285: <li><h3 id=reporting>Reporting problems</h3>
286:
1.9 deraadt 287: <p>
1.441 bentley 288: If you find a new security problem, you can mail it to
1.294 david 289: <a href="mailto:deraadt@openbsd.org">deraadt@openbsd.org</a>.
1.7 deraadt 290: <br>
1.5 deraadt 291: If you wish to PGP encode it (but please only do so if privacy is very
1.112 philen 292: urgent, since it is inconvenient) use this <a href="advisories/pgpkey.txt">pgp key</a>.
1.5 deraadt 293:
1.441 bentley 294: <li><h3 id=papers>Further Reading</h3>
295:
1.107 deraadt 296: <p>
1.389 lum 297: Numerous
1.441 bentley 298: <a href="events.html">papers</a> have been written by OpenBSD team members,
1.389 lum 299: many dedicated to security.
1.294 david 300: </ul>
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