bogofilter contrib/bogopass temp file vulnerability

[Matthias Andree]

bogofilter-SA-2002:01.bogopass

Topic:		vulnerability in bogopass

Announcement:	bogofilter-SA-2002:01
Writer:		Matthias Andree
Version:	1.00
Announced:	2002-11-29
Category:	contrib
Type:		temporary file created insecurely
Impact:		anonymous local file destruction or change
Credits:	-
Danger:		medium (the vulnerable version was replaced after 6
		        hours, the vulnerable program is not installed
			by default)

Affects:	bogofilter 0.9.0.4 (beta version)

Not affected:	bogofilter 0.9.0.3 and before
		bogofilter 0.9.0.5 and newer

Default install: unaffected.

Introduced:	2002-11-27 23:04:28 UTC (CVS)
		2002-11-27 23:11    bogofilter 0.9.0.4 released

Corrected:	2002-11-28 01:19:04 UTC (CVS) - disabled original version
		2002-11-28 03:32:47 UTC (CVS) - committed corrected version
		2002-11-28 04:26    bogofilter 0.9.0.5 released

0. Release history

2002-11-28	1.00 initial announcement

1. Background

Bogofilter is a software package to determine if a mail on its standard
input is spam or not.

2. Problem description

A vulnerability was found in the contrib/bogopass Perl program that was
added to bogofilter as of the 0.9.0.4 beta release (date: 2002-11-27
23:04:28 UTC in CVS) with bogofilter, but is not installed by default.

The bogopass program creates temporary files with the name
/tmp/bogopass.$$, where $$ is the process ID, with the open FH, ">file"
syntax of Perl, which uses O_TRUNC mode, not O_EXCL.

3. Impact

This vulnerability allows for anonymous file destruction or change, and
might be abused to further escalate the privileges of the local
attacker.

If bogopass is run by the root user, this may eventually lead to a
complete system compromise.

4. Workaround

Do not install or use the "bogopass" program that shipped with the
vulnerable versions (see above) of bogofilter.

5. Solution

Upgrade your bogofilter to version 0.9.0.5 beta, and reinstall the
bogopass program. Make sure you delete all copies of the old version of
bogopass.

bogofilter 0.9.0.5 is available from sourceforge:

http://sourceforge.net/project/showfiles.php?group_id=62265&release_id=118794

6. Solution details

revision 1.3
date: 2002/11/28 03:32:47;  author: m-a;  state: Exp;  lines: +67 -26

7. Other hints

Software that treats user input should not run as root if it can be
avoided. When installing bogofilter for system-wide use, make sure that
it runs as an unprivileged user to limit the impact of possible
vulnerabilities.

A. References

bogofilter home page: http://bogofilter.sourceforge.net/