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Hylafax: Insecure temporary file creation in xferfaxstats script


1.  Gentoo Linux Security Advisory

Version Information

Advisory Reference GLSA 200509-21 / hylafax
Release Date September 30, 2005
Latest Revision May 22, 2006: 02
Impact normal
Exploitable local
Package Vulnerable versions Unaffected versions Architecture(s)
net-misc/hylafax < 4.2.2 revision >= 4.2.0-r3, revision >= 4.2.1-r2, >= 4.2.2 All supported architectures

Related bugreports: #106882


Hylafax is vulnerable to linking attacks, potentially allowing a local user to overwrite arbitrary files.

2.  Impact Information


Hylafax is a client-server fax package for class 1 and 2 fax modems.


Javier Fernandez-Sanguino has discovered that xferfaxstats cron script supplied by Hylafax insecurely creates temporary files with predictable filenames.


A local attacker could create symbolic links in the temporary file directory, pointing to a valid file somewhere on the filesystem. When the xferfaxstats script of Hylafax is executed, this would result in the file being overwritten with the rights of the user running the script, which typically is the root user.

3.  Resolution Information


There is no known workaround at this time.


All Hylafax users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose net-misc/hylafax

4.  References


Page updated September 30, 2005

Summary: This is a Gentoo Linux Security Advisory

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