BIND 9 cache posioning exploit discoverd -- not the one on OpenBSD

as some of you may have noticed, a new weakness in BIND 9 has recently been discovered.  using this weakness, an attacker can remotely poison the cache of any BIND 9 server.  the attacker can do this due to a weakness in the transaction ID generation algorithm used.

when BIND 9 was first imported into OpenBSD, we decided not to use the default ID generation algorithm (LFSR, Linear Feedback Shift
Register) but to use a more proven algorithm (LCG, Linear Congruential Generator) instead.  thanks to this wise decision, the BIND 9 shipped with OpenBSD does not have this weakness.

the proactive security of OpenBSD strikes again,

 jakob

ref: http://www.trusteer.com/docs/bind9dns.html

 http://www.securiteam.com/securitynews/5VP0L0UM0A.html 

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A glance at the README.OpenBSD file for 4.1 in /usr/src/usr.sbin/bind shows (among other things):

- add LCG (Linear Congruential Generator) implementation to libisc
- use LCG instead of LFSR for ID generation until LFSR is proven reliable
- strlcpy/strlcat/snprintf fixes

Without digging into things deeper, it looks like this is unlikely to be an issue since the OBSD version doesn't rely on LFSR.

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