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Re: more bash parser bugs (CVE-2014-6277, CVE-2014-6278)


From: Chet Ramey <chet.ramey () case edu>
Date: Wed, 01 Oct 2014 14:27:54 -0400

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On 10/1/14, 2:20 PM, Hanno Böck wrote:
Haven't seen it here yet. lcamtuf now disclosed details of the two
further parser bugs he found:
http://lcamtuf.blogspot.de/2014/10/bash-bug-how-we-finally-cracked.html

Basically if anyone hasn't applied one of the prefix patches yet now's
the time to do so.

While prefixing should shield against them they should still be fixed
for good.

CVE-2014-6277 can still be triggered to segfault a fully patched bash:
bash -c "f(){ x(){ _;}; x(){ _;}<<a;}"

Second issue PoC on fully patched system:
env BASH_FUNC_x%%='() { _;}>_[$($())] { echo vuln;}' bash -c :

(both likely not exploitable due to prefix shielding, but should be
fixed anyway)

I have patches for these, and they are in the pipeline.

Chet

- -- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU    chet () case edu    http://cnswww.cns.cwru.edu/~chet/
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