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a2ps: Multiple vulnerabilities


1.  Gentoo Linux Security Advisory

Version Information

Advisory Reference GLSA 200501-02 / a2ps
Release Date January 04, 2005
Latest Revision May 22, 2006: 03
Impact normal
Exploitable local and remote
Package Vulnerable versions Unaffected versions Architecture(s)
app-text/a2ps < 4.13c-r2 >= 4.13c-r2 All supported architectures

Related bugreports: #75784, #61500


The fixps and psmandup scripts in the a2ps package are vulnerable to symlink attacks, potentially allowing a local user to overwrite arbitrary files. A vulnerability in a2ps filename handling could also result in arbitrary command execution.

2.  Impact Information


a2ps is an Any to Postscript filter that can convert to Postscript from many filetypes. fixps is a script that fixes errors in Postscript files. psmandup produces a Postscript file for printing in manual duplex mode.


Javier Fernandez-Sanguino Pena discovered that the a2ps package contains two scripts that create insecure temporary files (fixps and psmandup). Furthermore, we fixed in a previous revision a vulnerability in a2ps filename handling (CAN-2004-1170).


A local attacker could create symbolic links in the temporary files directory, pointing to a valid file somewhere on the filesystem. When fixps or psmandup is executed, this would result in the file being overwritten with the rights of the user running the utility. By enticing a user or script to run a2ps on a malicious filename, an attacker could execute arbitrary commands on the system with the rights of that user or script.

3.  Resolution Information


There is no known workaround at this time.


All a2ps users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=app-text/a2ps-4.13c-r2"

4.  References


Page updated January 04, 2005

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