# Exim filter
## Version: 0.14
-# $Id: system_filter.exim,v 1.4 2001/05/22 08:18:31 nigel Exp $
+# $Id: sysfilter.tmpl,v 1.1 2001/08/15 10:01:01 nigel Exp $
+## Exim system filter to refuse potentially harmful payloads in
+## mail messages
+## (c) 2000-2001 Nigel Metheringham <nigel@exim.org>
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 2 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; if not, write to the Free Software
+## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+## -A copy of the GNU General Public License is distributed with exim itself
+
+## -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
## If you haven't worked with exim filters before, read
## the install notes at the end of this file.
+## The install notes are not a replacement for the exim documentation
+## -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-#
+
+## -----------------------------------------------------------------------
# Only run any of this stuff on the first pass through the
# filter - this is an optomisation for messages that get
# queued and have several delivery attempts
## -----------------------------------------------------------------------
# Look for single part MIME messages with suspicious name extensions
# Check Content-Type header using quoted filename [content_type_quoted_fn_match]
-if $header_content-type: matches "(?:file)?name=(\"[^\"]+\\\\.(?:vb[se]|ws[fh]|jse?|exe|com|cmd|shs|hta|bat|scr|pif)\")"
+if $header_content-type: matches "(?:file)?name=(\"[^\"]+\\\\.(?:vb[se]|ws[fh]|jse?|exe|com|cmd|shs|hta|bat|scr|lnk|pif)\")"
then
fail text "This message has been rejected because it has\n\
potentially executable content $1\n\
seen finish
endif
# same again using unquoted filename [content_type_unquoted_fn_match]
-if $header_content-type: matches "(?:file)?name=([\\\\w.-]+\\\\.(?:vb[se]|ws[fh]|jse?|exe|com|cmd|shs|hta|bat|scr|pif))"
+if $header_content-type: matches "(?:file)?name=(.+\\\\.(?:vb[se]|ws[fh]|jse?|exe|com|cmd|shs|hta|bat|scr|lnk|pif))"
then
fail text "This message has been rejected because it has\n\
potentially executable content $1\n\
# in emails. These were used as the basis for
# the ILOVEYOU virus and its variants - many many varients
# Quoted filename - [body_quoted_fn_match]
-if $message_body matches "(?:Content-(?:Type:(?>\\\\s*)[\\\\w-]+/[\\\\w-]+|Disposition:(?>\\\\s*)attachment);(?>\\\\s*)(?:file)?name=|begin(?>\\\\s+)[0-7]{3,4}(?>\\\\s+))(\"[^\"]+\\\\.(?:vb[se]|ws[fh]|jse?|exe|com|cmd|shs|hta|bat|scr|pif)\")[\\\\s;]"
+if $message_body matches "(?:Content-(?:Type:(?>\\\\s*)[\\\\w-]+/[\\\\w-]+|Disposition:(?>\\\\s*)attachment);(?>\\\\s*)(?:file)?name=|begin(?>\\\\s+)[0-7]{3,4}(?>\\\\s+))(\"[^\"]+\\\\.(?:vb[se]|ws[fh]|jse?|exe|com|cmd|shs|hta|bat|scr|lnk|pif)\")[\\\\s;]"
then
fail text "This message has been rejected because it has\n\
a potentially executable attachment $1\n\
seen finish
endif
# same again using unquoted filename [body_unquoted_fn_match]
-if $message_body matches "(?:Content-(?:Type:(?>\\\\s*)[\\\\w-]+/[\\\\w-]+|Disposition:(?>\\\\s*)attachment);(?>\\\\s*)(?:file)?name=|begin(?>\\\\s+)[0-7]{3,4}(?>\\\\s+))([\\\\w.-]+\\\\.(?:vb[se]|ws[fh]|jse?|exe|com|cmd|shs|hta|bat|scr|pif))[\\\\s;]"
+if $message_body matches "(?:Content-(?:Type:(?>\\\\s*)[\\\\w-]+/[\\\\w-]+|Disposition:(?>\\\\s*)attachment);(?>\\\\s*)(?:file)?name=|begin(?>\\\\s+)[0-7]{3,4}(?>\\\\s+))(.+\\\\.(?:vb[se]|ws[fh]|jse?|exe|com|cmd|shs|hta|bat|scr|lnk|pif))[\\\\s;]"
then
fail text "This message has been rejected because it has\n\
a potentially executable attachment $1\n\
# shorter than the limits on pre exim 3.20 filters. This will
# make them significantly less efficient, but I am getting so
# many queries about this that requiring 3.2x appears unsupportable.
+# 0.14 15 August,2001
+# Added .lnk extension - most requested item :-)
+# Reformatted everything so its now built from a set of short
+# library files, cutting down on manual duplication.
+# Changed \w in filename detection to . - dodges locale problems
+# Explicit application of GPL after queries on license status
#
#### Install Notes
#
#
#### BASIS
#
-# The regexp that is used to pickup MIME/uuencoded parts is replicated
-# below (in perl format). You need to remember that exim converts
-# newlines to spaces in the message_body variable.
-#
-# (?:Content- # start of content header
-# (?:Type: (?>\s*) # rest of c/t header
-# [\w-]+/[\w-]+ # content-type (any)
-# |Disposition: (?>\s*) # content-disposition hdr
-# attachment) # content-disposition
-# ;(?>\s*) # ; space or newline
-# (?:file)?name= # filename=/name=
-# |begin (?>\s+) [0-7]{3,4} (?>\s+)) # begin octal-mode
-# (\"[^\"]+\. # quoted filename.
-# (?:vb[se] # list of extns
-# |ws[fh]
-# |jse?
-# |exe
-# |com
-# |cmd
-# |shs
-# |hta
-# |bat
-# |scr
-# |pif)
-# \" # end quote
-# |[\w.-]+\. # unquoted filename.ext
-# (?:vb[se] # list of extns
-# |ws[fh]
-# |jse?
-# |exe
-# |com
-# |cmd
-# |shs
-# |hta
-# |bat
-# |scr
-# |pif)
-# ) # end of filename capture
-# [\s;] # trailing ;/space/newline
+# The regexp that is used to pickup MIME/uuencoded body parts with
+# quoted filenames is replicated below (in perl format).
+# You need to remember that exim converts newlines to spaces in
+# the message_body variable.
+#
+# (?:Content- # start of content header
+# (?:Type: (?>\s*) # rest of c/t header
+# [\w-]+/[\w-]+ # content-type (any)
+# |Disposition: (?>\s*) # content-disposition hdr
+# attachment) # content-disposition
+# ;(?>\s*) # ; space or newline
+# (?:file)?name= # filename=/name=
+# |begin (?>\s+) [0-7]{3,4} (?>\s+)) # begin octal-mode
+# (\"[^\"]+\. # quoted filename.
+# (?:vb[se] # list of extns
+# |ws[fh]
+# |jse?
+# |exe
+# |com
+# |cmd
+# |shs
+# |hta
+# |bat
+# |scr
+# |lnk
+# |pif)
+# \" # end quote
+# ) # end of filename capture
+# [\s;] # trailing ;/space/newline
+
#
#
### [End]
git://git.exim.org / exim-website.git / commitdiff