Bolthole Filter 2.6.1 is susceptible to a buffer overflow in the save_embedded_address() function.
e81216105c9e6872a277520889e10eb6ed145339886c78f8534bc7ae33ead91a
From djb@cr.yp.to Wed Dec 15 14:21:02 2004
Date: 15 Dec 2004 08:16:36 -0000
From: D. J. Bernstein <djb@cr.yp.to>
To: securesoftware@list.cr.yp.to, filter@bolthole.com
Subject: [remote] [control] elm/bolthole filter 2.6.1 save_embedded_address
overflows address buffer
Ariel Berkman, a student in my Fall 2004 UNIX Security Holes course, has
discovered a remotely exploitable security hole in the elm/bolthole
filter program. I'm publishing this notice, but all the discovery
credits should be assigned to Berkman.
You are at risk if you feed incoming email through the filter program.
Anyone sending you email can take complete control over your account: he
can read and modify your files, watch the programs you're running, etc.
Proof of concept: On an x86 computer running FreeBSD 4.10, type
wget http://www.bolthole.com/filter/filter2.6.1.tar.gz
gunzip < filter2.6.1.tar.gz | tar -xf -
cd filter2.6.1
env TOUCH=/usr/bin/touch make
to download and compile the filter program, version 2.6.1 (current).
Then save the file 11.mail attached to this message, and type
./filter < 11.mail
with the unauthorized result that a file named x is removed from the
current directory. (I tested this with a 534-byte environment, as
reported by printenv | wc -c.)
Here's the bug: In filter.c, save_embedded_address() copies any amount
of data into an address[LONG_STRING] array.
---D. J. Bernstein, Associate Professor, Department of Mathematics,
Statistics, and Computer Science, University of Illinois at Chicago
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