full-disclosure - BZIP2 bomb question

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From: ashipp at messagelabs.com (Alex Shipp)
Subject: BZIP2 bomb question

>----- Original Message ----- 
>From: "Gregh" <chows@...mail.com.au>
>

>Please note I am not a good programmer here but here goes:
>
>I am wondering why, for those who HAVE to auto unpack, a script cannot be
>written which, upon receipt of an archive of any sort, inspects it for, as
>an example, 100K of the same character repeated (keeping in mind that the
>NULL character, chr$(7) etc have all been used for compressed bombs) and if
>there *IS* such a file, move the file to some safe location for later
manual
>inspection and if not, allow automatic unpacking etc.

Ignoring lots of technical details (!) this can indeed be done, and can be
used
along with lots of other heuristics to defend against compressed bombs.

There are implementaions that already do this.

Regards,

Alex

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