Scientific Linux Security Update : vixie-cron on SL5.x i386/x86_64

This script is Copyright (C) 2012 Tenable Network Security, Inc.

Synopsis :

The remote Scientific Linux host is missing one or more security

Description :

The vixie-cron package contains the Vixie version of cron. Cron is a
standard UNIX daemon that runs specified programs at scheduled times.
The vixie-cron package adds improved security and more powerful
configuration options to the standard version of cron.

A race condition was found in the way the crontab program performed
file time stamp updates on a temporary file created when editing a
user crontab file. A local attacker could use this flaw to change the
modification time of arbitrary system files via a symbolic link
attack. (CVE-2010-0424)

This update also fixes the following bugs :

- Cron jobs of users with home directories mounted on a
Lightweight Directory Access Protocol (LDAP) server or
Network File System (NFS) were often refused because
jobs were marked as orphaned (typically due to a
temporary NSS lookup failure, when NIS and LDAP servers
were unreachable). With this update, a database of
orphans is created, and cron jobs are performed as

- Previously, cron did not log any errors if a cron job
file located in the /etc/cron.d/ directory contained
invalid entries. An upstream patch has been applied to
address this problem and invalid entries in the cron job
files now produce warning messages.

- Previously, the '@reboot' crontab macro incorrectly ran
jobs when the crond daemon was restarted. If the user
used the macro on multiple machines, all entries with
the '@reboot' option were executed every time the crond
daemon was restarted. With this update, jobs are
executed only when the machine is rebooted.

- The crontab utility is now compiled as a
position-independent executable (PIE), which enhances
the security of the system.

- When the parent crond daemon was stopped, but a child
crond daemon was running (executing a program), the
'service crond status' command incorrectly reported that
crond was running. The source code has been modified,
and the 'service crond status' command now correctly
reports that crond is stopped.

- According to the pam(8) manual page, the cron daemon,
crond, supports access control with PAM (Pluggable
Authentication Module). However, the PAM configuration
file for crond did not export environment variables
correctly and, consequently, setting PAM variables via
cron did not work. This update includes a corrected
/etc/pam.d/crond file that exports environment variables
correctly. Setting pam variables via cron now works as
documented in the pam(8) manual page.

- Previously, the mcstransd daemon modified labels for the
crond daemon. When the crond daemon attempted to use the
modified label and mcstransd was not running, crond used
an incorrect label. Consequently, Security-Enhanced
Linux (SELinux) denials filled up the cron log, no jobs
were executed, and crond had to be restarted. With this
update, both mcstransd and crond use raw SELinux labels,
which prevents the problem.

- Previously, the crontab(1) and cron(8) manual pages
contained multiple typographical errors. This update
fixes those errors.

In addition, this update adds the following enhancement :

- Previously, the crontab utility did not use the
Pluggable Authentication Module (PAM) for verification
of users. As a consequence, a user could access crontab
even if access had been restricted (usually by being
denied in the access.conf file). With this update,
crontab returns an error message that the user is not
allowed to access crontab because of PAM configuration.

All vixie-cron users should upgrade to this updated package, which
resolves these issues and adds this enhancement.

See also :

Solution :

Update the affected vixie-cron and / or vixie-cron-debuginfo packages.

Risk factor :

Low / CVSS Base Score : 3.3

Family: Scientific Linux Local Security Checks

Nessus Plugin ID: 61273 ()

Bugtraq ID:

CVE ID: CVE-2010-0424

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