Instructions for Sendmail and Postfix to stop messages with long Date: headers.
0a78732b5488a64a94bdb50e95db3aa08911ecb7b7737f1988d5d3fc12311f30
Sendmail filter rule to stop Outlook exploit from Koos van den Hout <koos@KZDOOS.XS4ALL.NL>
Also on http://www.cetis.hvu.nl/~koos/outlookoverflow.txt
with tabs in the right places :)
#
# this is a filter to make sendmail reject messages with Date: headers
# that are too long. This is used in the latest Outlook exploit.
#
# You NEED:
# - a sendmail that understands regex maps. I had to specially compile this
# into 8.11 ! Add to sendmail-8.11.0/devtools/Site/site.config.m4
# define(`confMAPDEF',`-DMAP_REGEX') and rebuild from scratch
#
# The filter simply rejects messages with a date header longer (total!)
# then 60 chars
#
# Then add this part to your .mc file in the different areas and regenerate
# your .cf file
#
# 2000-07-21 Originally written
#
# if you cut and paste this:
# tabs are in use in the '^R' lines
#
# Koos van den Hout
# http://www.cetis.hvu.nl/~koos/
# http://www.virtualbookcase.com/
#
LOCAL_CONFIG
Klinetoolong regex -a@MATCH ^.{60,}$
LOCAL_RULESETS
HDate: $>+CheckDate
SCheckDate
R$* $: $(linetoolong $1 $)
R@MATCHi $#error $: 553 Date Header too long error
R$*i $@ OK
--
Koos van den Hout, PGP keyid RSA/1024 0xCA845CB5 via keyservers
koos@kzdoos.xs4all.nl or DSS/1024 0xF0D7C263 -?)
Fax +31-30-2817051 Visit my site about books with reviews /\\
http://www.cetis.hvu.nl/~koos/ http://www.virtualbookcase.com/ _\_V
quick Postfix check for Outlook date exploit from Mark Lastdrager <mark@security.nl>
Hi,
With a little help from Koos van den Hout I made a small header_check
for Postfix to prevent people from exploiting the latest Outlook
bug. A quick test shows it works but don't come complaining when it
doesn't ;-)
In your main.cf put this line:
header_checks = regexp:/etc/postfix/header_checks
(path depends on where your postfix config lives)
In header_checks put:
/^Date:.{60,}$/ REJECT
This will reject messages with a date line longer than 60 chars.
Don't forget postfix reload ;-)
Mark Lastdrager
Pine Internet
--
email: mark@lastdrager.nl :: ML1400-RIPE :: tel. +31-70-3111010
http://www.pine.nl :: RIPE RegID nl.pine :: fax. +31-70-3111011
PGP key ID 92BB81D1 :: Dutch security news @ http://security.nl
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