RHEL 2.1 : sendmail (RHSA-2002:259)
Medium Nessus Plugin ID 12335
SynopsisThe remote Red Hat host is missing one or more security updates.
DescriptionThe sendmail packages shipped with Red Hat Linux Advanced Server have a security bug if sendmail is configured to use smrsh. This security errata release fixes the problem.
[Updated 06 Feb 2003] Added fixed packages for Advanced Workstation 2.1
SMRSH (the SendMail Restricted SHell) is a /bin/sh replacement for Sendmail. It provides the ability to limit the set of executable programs available to Sendmail.
A bug in the version of smrsh packaged as part of Sendmail 8.12.6 and 8.11.6 allows attackers to bypass shrsh's intended restrictions. This can be done by inserting additional commands after '||' or '/' characters, which are not properly filtered or verified. A sucessful attack would allow an attacker who has a local account on a system to execute arbitrary binaries as themselves by utilizing their .forward file.
Because sendmail as shipped with Red Hat Linux Advanced Server is not configured to use smrsh, this issue only affects users who have customized their sendmail configuration to use smrsh.
Users who have configured sendmail to use smrsh should update to these errata packages which contain a backported security fix, and are therefore not vulnerable to this issue.
SolutionUpdate the affected packages.