A boundary error condition in mpg123 version 0.59r allows for remote compromise.
36e5f420010b7ec3f07c25f3fb25b69ec231d8b95a523e1b4eeac6aef5702688
From djb@cr.yp.to Wed Dec 15 14:20:39 2004
Date: 15 Dec 2004 08:14:59 -0000
From: D. J. Bernstein <djb@cr.yp.to>
To: securesoftware@list.cr.yp.to, hippm@informatik.uni-tuebingen.de
Subject: [remote] [control] mpg123 0.59r find_next_file overflows linetmp
buffer
Bartlomiej Sieka, a student in my Fall 2004 UNIX Security Holes course,
has discovered a remotely exploitable security hole in mpg123. I'm
publishing this notice, but all the discovery credits should be assigned
to Sieka.
You are at risk if you use mpg123 --list to take an MP3 playlist from a
web page (or any other source that could be controlled by an attacker).
Whoever provides that input then has complete control over your account:
he can read and modify your files, watch the programs you're running,
etc.
Of course, when you accept a playlist from someone else, you are running
the risk that the playlist will include some of your files, conceivably
secret audio files. But the mpg123 documentation does not suggest that
there is any larger risk.
Proof of concept: On an x86 computer running FreeBSD 4.10, as root, type
cd /usr/ports/audio/mpg123
make install
to download and compile the mpg123 program, version 0.59r (current ports
version; note that pre0.59s does not appear to have fixed the bug).
Then, as any user, save the file 8.list attached to this message, and
type
mkdir 1234567890123456789
mv 8.list 1234567890123456789/8.list
mpg123 -s --list 1234567890123456789/8.list >/dev/null
with the unauthorized result that a file named EXPLOIT is created in the
current directory. (I tested this with a 4621-byte environment, as
reported by printenv | wc -c.)
Here's the bug: In playlist.c, find_next_file() uses strcat() to copy
any amount of data into a 1024-byte linetmp[] array.
---D. J. Bernstein, Associate Professor, Department of Mathematics,
Statistics, and Computer Science, University of Illinois at Chicago
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