TITLE:
Trustix Fcron "convert-fcrontab" Two Vulnerabilities

SECUNIA ADVISORY ID:
SA18719

VERIFY ADVISORY:
http://secunia.com/advisories/18719/

CRITICAL:
Less critical

IMPACT:
Privilege escalation

WHERE:
Local system

OPERATING SYSTEM:
Trustix Secure Linux 2.2
http://secunia.com/product/4641/

DESCRIPTION:
Two vulnerabilities have been reported in Fcron, which can be
exploited by malicious, local users to gain escalated privileges.

1) A boundary error exists in convert-fcrontab when handling an
overly long username supplied via the command line. This can be
exploited to cause a heap-based buffer overflow and may allow
arbitrary code execution.

2) Missing validation of the username supplied to convert-fcrontab
can be exploited to cause the application to create temporary files
insecurely outside of "/var/spool/fcron" via directory traversal
attacks. This can be exploited via symlink attacks to create or
overwrite arbitrary files with the privileges of the root user.

Successful exploitation requires that convert-fcrontab is setuid root
(reportedly default setting on Trustix 2.2).

The vulnerability has been reported in Fcron version 2.9.5 included
with Trustix 2.2. Other versions may also be affected.

SOLUTION:
Remove setuid bits from convert-fcrontab.

PROVIDED AND/OR DISCOVERED BY:
1) Adam Zabrocki
2) Karol Wiesek

ORIGINAL ADVISORY:
http://lists.grok.org.uk/pipermail/full-disclosure/2006-February/041888.html
http://lists.grok.org.uk/pipermail/full-disclosure/2006-February/041900.html

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