Re: Algorithmic Bugs

["Thomas Ptacek" <tqbf () matasano com>]

Tim Newsham worked on this in 1997-1998 (and in that respect the paper
gets its cites a bit wrong; I'm pretty sure there are published hash
table results prior to 2003). My sense is that the "classic" attack
here is "turn chaining hash tables into linked lists with a collision
extension function".

On 1/10/07, Dave Aitel <dave () immunityinc com> wrote:
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> Best paper at a conference I went to recently here in Miami Beach.
>
>
> http://www.cs.wisc.edu/~smithr/pubs/acsac2006.pdf
>
> Summery:
> You can send a remarkably small stream of data at a NIDS and cause it
> to go to 100% CPU and stop doing analysis if you send the RIGHT stream
> of data. This is basically undetectable (i.e. does not crash snort).
> Was fixed in Snort 2.6.1 (I believe). Some snort rules have a 1
> million to 1 expansion if you do it right (from what I read - I
> haven't tested this out yet - but it would make a great CANVAS module!)
>
> The presentation is clearer than the paper. I hope they put it online.
>
> Similar bugs exist in major commercial Python exploitation frameworks
> (i.e. you can tartrap CANVAS if you do it right). The more high level
> the language, the easier it is to get caught by something like this.
>
> - -dave
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