Technical Description

A vulnerability has been identified in various Blue Coat products, which could be exploited by remote attackers to poison a vulnerable DNS cache. This issue is caused due to the DNS server not sufficiently randomising DNS transaction IDs and UDP source ports in the DNS queries that they produce, which may allow an attacker to more easily forge DNS answers that can poison DNS caches.

Affected Products

Blue Coat ProxySG versions prior to 4.2.8.7
Blue Coat ProxySG versions prior to 5.2.4.3
Blue Coat Director versions prior to 4.2.2.4
Blue Coat Director versions prior to 5.2.2.5
Blue Coat ProxyRA versions prior to 2.3.2.1
Blue Coat PacketShaper versions prior to 8.3.2
Blue Coat PacketShaper versions prior to 8.4.0
Blue Coat iShaper versions prior to 8.3.2

Solution

Upgrade to Blue Coat ProxySG version 4.2.8.7 or 5.2.4.3, Director version 4.2.2.4 or 5.2.2.5, ProxyRA version 2.3.2.1, PacketShaper version 8.3.2 or 8.4.0, and iShaper version 8.3.2 :
http://www.bluecoat.com/support/downloads

References

http://www.vupen.com/english/advisories/2008/2139
http://www.bluecoat.com/support/security-advisories/dns_cache_poisoning

Credits

Vulnerability reported by Dan Kaminsky (IOActive).

ChangeLog

2008-07-18 : Initial release

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