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 by Red Hat is not configured to use smrsh,
this issue only affects Red Hat Linux Advanced Server users who have
customized their sendmail configuration to use smrsh.
An errata has been issued which should help the problem described in this bug report.
This report is therefore being closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files, please follow the link below. You may reopen
this bug report if the solution does not work for you.