CVE-2008-5162

The arc4random function in the kernel in FreeBSD 6.3 through 7.1 does not have a proper entropy source for a short time period immediately after boot, which makes it easier for attackers to predict the functions return values and conduct certain attacks against the GEOM framework and various network protocols, related to the Yarrow random number generator.

Weakness

The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers.

Affected Software

Potential Mitigations

• Use a well-vetted algorithm that is currently considered to be strong by experts in the field, and select well-tested implementations with adequate length seeds.
• In general, if a pseudo-random number generator is not advertised as being cryptographically secure, then it is probably a statistical PRNG and should not be used in security-sensitive contexts.
• Pseudo-random number generators can produce predictable numbers if the generator is known and the seed can be guessed. A 256-bit seed is a good starting point for producing a “random enough” number.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/112.html
• https://cwe.mitre.org/data/definitions/485.html
• https://cwe.mitre.org/data/definitions/59.html

References

• http://osvdb.org/50137
• http://secunia.com/advisories/32871
• http://security.freebsd.org/advisories/FreeBSD-SA-08:11.arc4random.asc
• http://securitytracker.com/id?1021276
• http://www.securityfocus.com/bid/32447