3.3 - RHSA-2012:0304

Problem Description:

An updated vixie-cron package that fixes one security issue, several bugs, and adds one enhancement is now available for Red Hat Enterprise Linux 5.

The Red Hat Security Response Team has rated this update as having low security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.

2. Relevant releases/architectures:

Red Hat Enterprise Linux (v. 5 server) - i386, ia64, ppc, s390x, x86_64 Red Hat Enterprise Linux Desktop (v. 5 client) - i386, x86_64

3. 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)

Red Hat would like to thank Dan Rosenberg for reporting this issue.

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 expected. (BZ#455664)

* 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. (BZ#460070)

* 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. (BZ#476972)

* The crontab utility is now compiled as a position-independent executable (PIE), which enhances the security of the system. (BZ#480930)

* 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. (BZ#529632)

* 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. (BZ#541189)

* 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. (BZ#625016)

* Previously, the crontab(1) and cron(8) manual pages contained multiple typographical errors. This update fixes those errors. (BZ#699620, BZ#699621)

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. (BZ#249512)

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

4. Solution:

Before applying this update, make sure all previously-released errata relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to use the Red Hat Network to apply this update are available at https://access.redhat.com/kb/docs/DOC-11259

5. Bugs fixed (http://bugzilla.redhat.com/):

455664 - Adoptions at the crontab orphanage needed 460070 - cronjobs in /etc/cron.d entries with an invalid username produce no error in the logs 476972 - crontab error with @reboot entry 480930 - Make crontab a PIE 529632 - [PATCH] "service crond status" return invalid status 541189 - cron and /etc/security/pam_env.conf problem 565809 - CVE-2010-0424 vixie-cron, cronie: Race condition by setting timestamp of user's crontab file, when editing the file 625016 - crond requires a restart if mcstransd is stopped 699620 - Typo in patch for crond manpage removes mention of cron.d 699621 - man page typo -- two be -- should be not two be's ;)