From djb@cr.yp.to Wed Dec 15 14:21:48 2004
Date: 15 Dec 2004 08:22:15 -0000
From: D. J. Bernstein <djb@cr.yp.to>
To: securesoftware@list.cr.yp.to, mike@mikekohn.net
Subject: [remote] [control] ringtonetools 2.22 parse_emelody overflows song
    buffer

Qiao Zhang, a student in my Fall 2004 UNIX Security Holes course, has
discovered a remotely exploitable security hole in ringtonetools. I'm
publishing this notice, but all the discovery credits should be assigned
to Zhang.

You are at risk if you take an eMelody file from an email message (or a
web page or any other source that could be controlled by an attacker)
and feed that file through ringtonetools. Whoever provides that file
then has complete control over your account: she can read and modify
your files, watch the programs you're running, etc.

The ringtonetools documentation does not tell users to avoid taking
input from the network. In fact, the documentation explicitly suggests
downloading eMelody files from the web.

Proof of concept: On an x86 computer running FreeBSD 4.10, type

   wget http://downloads.mikekohn.net/ringtonetools/ringtonetools-2.22.tar.gz
   gunzip < ringtonetools-2.22.tar.gz | tar -xf -
   cd ringtonetools-2.22
   make

to download and compile the ringtonetools program, version 2.22
(current). Then save the file 31.emelody attached to this message, and
type

   ./ringtonetools 31.emelody

with the unauthorized result that a file named EXPLOITED is created in
the current directory.

Here's the bug: In parse_emelody.c, parse_emelody() reads any amount of
input into a 1024-byte song[] array.

---D. J. Bernstein, Associate Professor, Department of Mathematics,
Statistics, and Computer Science, University of Illinois at Chicago

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