Sendmail: Denial of Service
Gentoo Linux Security Advisory
||GLSA 200606-19 / sendmail
||June 15, 2006
||June 15, 2006: 01
All supported architectures
Faulty multipart MIME messages can cause forked Sendmail processes to
Sendmail is a popular mail transfer agent (MTA).
Frank Sheiness discovered that the mime8to7() function can recurse
endlessly during the decoding of multipart MIME messages until the
stack of the process is filled and the process crashes.
By sending specially crafted multipart MIME messages, a remote
attacker can cause a subprocess forked by Sendmail to crash. If
Sendmail is not set to use a randomized queue processing, the attack
will effectively halt the delivery of queued mails as well as the
malformed one, incoming mail delivered interactively is not affected.
Additionally, on systems where core dumps with an individual naming
scheme (like "core.pid") are enabled, a filesystem may fill up with
core dumps. Core dumps are disabled by default in Gentoo.
The Sendmail 8.13.7 release information offers some workarounds, please
see the Reference below. Note that the issue has actually been fixed in
the 8.13.6-r1 ebuild.
All Sendmail users should upgrade to the latest version:
Code Listing 3.1: Resolution
# emerge --sync
# emerge --ask --oneshot --verbose ">=mail-mta/sendmail-8.13.6-r1"