OpenBSD XOR weak security
| openbsd-xor-weak-security (41155) |  Low Risk |
Description:
OpenBSD could provide weaker than expected security, caused by a vulnerability in the pseudo random number generator (PRNG) that uses XOR and "Algorithm X2", where predictable sequence IDs are generated. By observing some consecutive transaction ID values, a remote attacker could exploit this vulnerability to guess the next IP fragmentation ID and perform OS fingerprinting.
Note: This vulnerability also affects Mac OS X, DragonflyBSD and FreeBSD.
Platforms Affected:
- DragonFlyBSD, DragonFlyBSD 1.0 - 1.10.1
- FreeBSD, FreeBSD 4.10
- FreeBSD, FreeBSD 4.4
- FreeBSD, FreeBSD 4.5
- FreeBSD, FreeBSD 4.6
- FreeBSD, FreeBSD 4.6.2
- FreeBSD, FreeBSD 4.7
- FreeBSD, FreeBSD 4.8
- FreeBSD, FreeBSD 4.9
- FreeBSD, FreeBSD 5.0 Alpha
- FreeBSD, FreeBSD 5.0
- FreeBSD, FreeBSD 5.1
- FreeBSD, FreeBSD 5.2
- FreeBSD, FreeBSD 5.3
- FreeBSD, FreeBSD 6.0
- FreeBSD, FreeBSD 6.1
- FreeBSD, FreeBSD 6.2
- FreeBSD, FreeBSD 6.3
- OpenBSD, OpenBSD 2.6 - 3.4
Remedy:
Apply the appropriate update for your system. See References.
Consequences:
Gain Access
References:
- Apple Web site, Darwin at http://www.opensource.apple.com/darwinsource/.
- Apple Web site, Mac OS X at http://www.apple.com/macosx/.
- DragonFlyBSD Web site, DragonFlyBSD at http://www.dragonflybsd.org/index.shtml.
- FreeBSD Web site, FreeBSD at http://www.freebsd.org/.
- OpenBSD Web site, OpenBSD at http://www.openbsd.org/.
- Trusteer Web site, OpenBSD DNS Cache Poisoning and Multiple O/S Predictable IP ID Vulnerability at http://www.trusteer.com/docs/dnsopenbsd.html.
- BID-27647: OpenBSD PRNG DNS Cache Poisoning and Predictable IP ID Weakness
- CVE-2008-1147: A certain pseudo-random number generator (PRNG) algorithm that uses XOR and 2-bit random hops (aka Algorithm X2), as used in OpenBSD 2.6 through 3.4, Mac OS X 10 through 10.5.1, FreeBSD 4.4 through 7.0, and DragonFlyBSD 1.0 through 1.10.1, allows remote attackers to guess sensitive values such as IP fragmentation IDs by observing a sequence of previously generated values. NOTE: this issue can be leveraged for attacks such as injection into TCP packets and OS fingerprinting.
- SA28819: OpenBSD DNS Server PRNG Transaction ID Vulnerability
Reported:
Feb 06, 2008
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