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Vixie Cron: Denial of Service


1.  Gentoo Linux Security Advisory

Version Information

Advisory Reference GLSA 200704-11 / vixie-cron
Release Date April 16, 2007
Latest Revision April 16, 2007: 01
Impact low
Exploitable local
Package Vulnerable versions Unaffected versions Architecture(s)
sys-process/vixie-cron < 4.1-r10 >= 4.1-r10 All supported architectures

Related bugreports: #164466


The Gentoo implementation of Vixie Cron is vulnerable to a local Denial of Service.

2.  Impact Information


Vixie Cron is a command scheduler with extended syntax over cron.


During an internal audit, Raphael Marichez of the Gentoo Linux Security Team found that Vixie Cron has weak permissions set on Gentoo, allowing for a local user to create hard links to system and users cron files, while a st_nlink check in database.c will generate a superfluous error.


Depending on the partitioning scheme and the "cron" group membership, a malicious local user can create hard links to system or users cron files that will trigger the st_link safety check and prevent the targeted cron file from being run from the next restart or database reload.

3.  Resolution Information


There is no known workaround at this time.


All Vixie Cron users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=sys-process/vixie-cron-4.1-r10"

4.  References


Page updated April 16, 2007

Summary: This is a Gentoo Linux Security Advisory

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