Multiple DNS implementations vulnerable to cache poisoning
Patrick W. Gilmore
patrick at ianai.net
Wed Jul 9 15:15:20 CDT 2008
On Jul 9, 2008, at 4:07 PM, Fernando Gont wrote:
> At 12:41 p.m. 09/07/2008, Steven M. Bellovin wrote:
>> It's worth noting that the basic idea of the attack isn't new. Paul
>> Vixie described it in 1995 at the Usenix Security Conference
>> -- in a section titled "What We Cannot Fix", he wrote:
>> With only 16 bits worth of query ID and 16 bits worth of UDP
>> port number, it's hard not to be predictable. A determined
>> attacker can try all the numbers in a very short time and can
>> use patterns derived from examination of the freely available
>> BIND code. Even if we had a white noise generator to help
>> randomize our numbers, it's just too easy to try them all.
> We have one IETF ID on port randomization for years: http://www.gont.com.ar/drafts/port-randomization/index.html
> While this does not make the attack impossible, it does make it much
> The same thing applies to those RST attacks circa 2004.
> Most of these blind attacks assume the source port numbers are easy
> to guess. But... why should they?
Because many name servers use one port, or easily guessable sequence
More information about the NANOG