several functional and organisation changes

diff --git a/filter/body_unquoted_fn_match b/filter/body_unquoted_fn_match
index 3e557a118379b75fae22bd63f9f464945b126b14..6623029f3d3ca0fc20a4c55ea4259fbce5673b44 100644 (file)
--- a/filter/body_unquoted_fn_match
+++ b/filter/body_unquoted_fn_match
@@ -1,9 +1,9 @@
-# $Id$
+# $Id: body_unquoted_fn_match,v 1.1 2001/05/18 10:28:13 nigel Exp $
 #
 # Match a body attachment with unquoted filename
 #
 #include header_regexp
-  ([\w.-]+\.                                   # unquoted filename.ext
+  (.+\.                                                # unquoted filename.ext
 #include extension_regexp
   )                                            # end of filename capture
   [\s;]                                                # trailing ;/space/newline

diff --git a/filter/content_type_unquoted_fn_match b/filter/content_type_unquoted_fn_match
index f77fdcc71397c03816fc3cac2ba7f8f889e72af4..f7dec75f710ce547dcb23668c31603a9d5829b05 100644 (file)
--- a/filter/content_type_unquoted_fn_match
+++ b/filter/content_type_unquoted_fn_match
@@ -1,8 +1,8 @@
-# $Id$
+# $Id: content_type_unquoted_fn_match,v 1.1 2001/05/18 10:28:13 nigel Exp $
 #
 # Match the content-type header with quoted filename
 #
 #include content_type_header
-  ([\w.-]+\.                                   # unquoted filename.ext
+  (.+\.                                                # unquoted filename.ext
 #include extension_regexp
   )                                            # end of filename capture

diff --git a/filter/extension_regexp b/filter/extension_regexp
index f8e2f386b3e70bb724a1e7127727a3bc44fc499f..9642500e456bf35d10021dbe2c2dcdc6c9d41111 100644 (file)
--- a/filter/extension_regexp
+++ b/filter/extension_regexp
@@ -1,4 +1,4 @@
-# $Id$
+# $Id: extension_regexp,v 1.1 2001/05/18 10:28:13 nigel Exp $
 # matches the list of extensions
 # uses non-capturing brackets
        (?:vb[se]                               # list of extns
@@ -11,4 +11,5 @@
        |hta
        |bat
        |scr
+       |lnk
        |pif)

diff --git a/filter/mkfilter.pl b/filter/mkfilter.pl
new file mode 100644 (file)
index 0000000..41dbfbb
--- /dev/null
+++ b/filter/mkfilter.pl
@@ -0,0 +1,74 @@
+#!/usr/bin/perl
+#
+use strict;
+use FileHandle;
+
+\f
+
+sub process_refile {
+    my $fn = shift;
+
+    my $re;
+    print STDERR "Opening $fn\n";
+    my $fh = FileHandle->new($fn, 'r') || die $!;
+    while (<$fh>) {
+       chomp();
+       # process includes
+       if (/^\#include\s/) {
+           my($junk, $nfn) = split;
+           $re .= process_refile($nfn);
+           next;
+       }
+       # ignore comments starting at the begining of the line
+       next if (/^\#/);
+       # dispose of comments with their leading spaces
+       s/\s+\#.*$//;
+       # recode \" -> "
+       s/\\\"/\"/g;
+       # double all \ (twice)
+       s/\\/\\\\/g;
+       s/\\/\\\\/g;
+       # escape " again
+       s/\"/\\\"/g;
+       # remove all space
+       s/\s+//g;
+       # add to re
+       $re .= $_;
+    }
+    return $re;
+}
+
+\f
+
+sub process_recfile {
+    my $fn = shift;
+
+    my $re;
+    print STDERR "Opening $fn\n";
+    my $fh = FileHandle->new($fn, 'r') || die $!;
+    while (<$fh>) {
+       chomp();
+       # process includes
+       if (/^\#include\s/) {
+           my($junk, $nfn) = split;
+           $re .= process_recfile($nfn);
+           next;
+       }
+       # skip comment only and blank lines
+       next if (/^\#/);
+       next if (/^\s*$/);
+       $re .= "#\t$_\n";
+    }
+    return $re;
+}
+
+\f
+
+# main
+{
+    while(<>) {
+       s/\[\[([a-z0-9_]+)\]\]/process_refile($1)/ge;
+       s/\[\<([a-z0-9_]+)\>\]/process_recfile($1)/ge;
+       print;
+    }
+}

diff --git a/filter/sysfilter.tmpl b/filter/sysfilter.tmpl
new file mode 100644 (file)
index 0000000..3d22546
--- /dev/null
+++ b/filter/sysfilter.tmpl
@@ -0,0 +1,222 @@
+# Exim filter
+## Version: 0.14
+#      $Id: system_filter.exim,v 1.4 2001/05/22 08:18:31 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
+#
+# we express this in reverse so we can just bail out
+# on inappropriate messages
+#
+if not first_delivery
+then
+  finish
+endif
+
+## -----------------------------------------------------------------------
+# Check for MS buffer overruns as per BUGTRAQ.
+# http://www.securityfocus.com/frames/?content=/templates/article.html%3Fid%3D61
+# This could happen in error messages, hence its placing
+# here...
+# We substract the first n characters of the date header
+# and test if its the same as the date header... which
+# is a lousy way of checking if the date is longer than
+# n chars long
+if ${length_80:$header_date:} is not $header_date:
+then
+  fail text "This message has been rejected because it has\n\
+            an overlength date field which can be used\n\
+            to subvert Microsoft mail programs\n\
+             The following URL has further information\n\
+            http://www.securityfocus.com/frames/?content=/templates/article.html%3Fid%3D61"
+  seen finish
+endif
+
+## -----------------------------------------------------------------------
+# These messages are now being sent with a <> envelope sender, but
+# blocking all error messages that pattern match prevents
+# bounces getting back.... so we fudge it somewhat and check for known
+# header signatures.  Other bounces are allowed through.
+if $header_from: contains "@sexyfun.net"
+then
+  fail text "This message has been rejected since it has\n\
+            the signature of a known virus in the header."
+  seen finish
+endif
+if error_message and $header_from: contains "Mailer-Daemon@"
+then
+  # looks like a real error message - just ignore it
+  finish
+endif
+
+## -----------------------------------------------------------------------
+# 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 "[[content_type_quoted_fn_match]]"
+then
+  fail text "This message has been rejected because it has\n\
+            potentially executable content $1\n\
+            This form of attachment has been used by\n\
+             recent viruses or other malware.\n\
+            If you meant to send this file then please\n\
+            package it up as a zip file and resend it."
+  seen finish
+endif
+# same again using unquoted filename [content_type_unquoted_fn_match]
+if $header_content-type: matches "[[content_type_unquoted_fn_match]]"
+then
+  fail text "This message has been rejected because it has\n\
+            potentially executable content $1\n\
+            This form of attachment has been used by\n\
+             recent viruses or other malware.\n\
+            If you meant to send this file then please\n\
+            package it up as a zip file and resend it."
+  seen finish
+endif
+
+
+## -----------------------------------------------------------------------
+# Attempt to catch embedded VBS attachments
+# 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 "[[body_quoted_fn_match]]"
+then
+  fail text "This message has been rejected because it has\n\
+            a potentially executable attachment $1\n\
+            This form of attachment has been used by\n\
+             recent viruses or other malware.\n\
+            If you meant to send this file then please\n\
+            package it up as a zip file and resend it."
+  seen finish
+endif
+# same again using unquoted filename [body_unquoted_fn_match]
+if $message_body matches "[[body_unquoted_fn_match]]"
+then
+  fail text "This message has been rejected because it has\n\
+            a potentially executable attachment $1\n\
+            This form of attachment has been used by\n\
+             recent viruses or other malware.\n\
+            If you meant to send this file then please\n\
+            package it up as a zip file and resend it."
+  seen finish
+endif
+## -----------------------------------------------------------------------
+
+
+#### Version history
+#
+# 0.01 5 May 2000
+#      Initial release
+# 0.02 8 May 2000
+#      Widened list of content-types accepted, added WSF extension
+# 0.03 8 May 2000
+#      Embedded the install notes in for those that don't do manuals
+# 0.04 9 May 2000
+#      Check global content-type header.  Efficiency mods to REs
+# 0.05 9 May 2000
+#      More minor efficiency mods, doc changes
+# 0.06 20 June 2000
+#      Added extension handling - thx to Douglas Gray Stephens & Jeff Carnahan
+# 0.07 19 July 2000
+#      Latest MS Outhouse bug catching
+# 0.08 19 July 2000
+#      Changed trigger length to 80 chars, fixed some spelling
+# 0.09 29 September 2000
+#      More extensions... its getting so we should just allow 2 or 3 through
+# 0.10 18 January 2001
+#      Removed exclusion for error messages - this is a little nasty
+#      since it has other side effects, hence we do still exclude
+#      on unix like error messages
+# 0.11 20 March, 2001
+#      Added CMD extension, tidied docs slightly, added RCS tag
+#      ** Missed changing version number at top of file :-(
+# 0.12 10 May, 2001
+#      Added HTA extension
+# 0.13 22 May, 2001
+#      Reformatted regexps and code to build them so that they are
+#      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
+#
+# Exim filters run the exim filter language - a very primitive
+# scripting language - in place of a user .forward file, or on
+# a per system basis (on all messages passing through).
+# The filtering capability is documented in the main set of manuals
+# a copy of which can be found on the exim web site
+#      http://www.exim.org/
+#
+# To install, copy the filter file (with appropriate permissions)
+# to /etc/exim/system_filter.exim and add to your exim config file
+# [location is installation depedant - typicaly /etc/exim/config ]
+# in the first section the line:-
+#      message_filter = /etc/exim/system_filter.exim
+#      message_body_visible = 5000
+#
+# You may also want to set the message_filter_user & message_filter_group
+# options, but they default to the standard exim user and so can
+# be left untouched.  The other message_filter_* options are only
+# needed if you modify this to do other functions such as deliveries.
+# The main exim documentation is quite thorough and so I see no need
+# to expand it here...
+#
+# Any message that matches the filter will then be bounced.
+# If you wish you can change the error message by editing it
+# in the section above - however be careful you don't break it.
+#
+# After install exim should be restarted - a kill -HUP to the
+# daemon will do this.
+#
+#### LIMITATIONS
+#
+# This filter tries to parse MIME with a regexp... that doesn't
+# work too well.  It will also only see the amount of the body
+# specified in message_body_visible
+#
+#### BASIS
+#
+# 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.
+#
+[<body_quoted_fn_match>]
+#
+#
+### [End]

diff --git a/filter/system_filter.exim b/filter/system_filter.exim
index f920ac8ca5a5143a1fd71cc9b43430124296ab1c..ecef5b6d91050484c471f7c3fde89867a330e2ac 100644 (file)
--- a/filter/system_filter.exim
+++ b/filter/system_filter.exim
@@ -1,6 +1,6 @@
 # Exim filter
-## Version: 0.13
-#      $Id: system_filter.exim,v 1.3 2001/05/18 10:28:13 nigel Exp $
+## Version: 0.14
+#      $Id: system_filter.exim,v 1.4 2001/05/22 08:18:31 nigel Exp $
 
 ## If you haven't worked with exim filters before, read
 ## the install notes at the end of this file.
@@ -18,7 +18,8 @@ then
   finish
 endif
 
-# Check for MS buffer overruns as per latest BUGTRAQ.
+## -----------------------------------------------------------------------
+# Check for MS buffer overruns as per BUGTRAQ.
 # http://www.securityfocus.com/frames/?content=/templates/article.html%3Fid%3D61
 # This could happen in error messages, hence its placing
 # here...
@@ -29,21 +30,22 @@ endif
 if ${length_80:$header_date:} is not $header_date:
 then
   fail text "This message has been rejected because it has\n\
-            \tan overlength date field which can be used\n\
-            \tto subvert Microsoft mail programs\n\
-             \tThe following URL has further information\n\
-            \thttp://www.securityfocus.com/frames/?content=/templates/article.html%3Fid%3D61"
+            an overlength date field which can be used\n\
+            to subvert Microsoft mail programs\n\
+             The following URL has further information\n\
+            http://www.securityfocus.com/frames/?content=/templates/article.html%3Fid%3D61"
   seen finish
 endif
 
-# This is a nasty compromise.
-# This crud is now being sent with a <> envelope sender, but
+## -----------------------------------------------------------------------
+# These messages are now being sent with a <> envelope sender, but
 # blocking all error messages that pattern match prevents
-# bounces getting back.... so we fudge it somewhat
+# bounces getting back.... so we fudge it somewhat and check for known
+# header signatures.  Other bounces are allowed through.
 if $header_from: contains "@sexyfun.net"
 then
   fail text "This message has been rejected since it has\n\
-               \tthe signature of a known virus in the header."
+            the signature of a known virus in the header."
   seen finish
 endif
 if error_message and $header_from: contains "Mailer-Daemon@"
@@ -52,56 +54,60 @@ then
   finish
 endif
 
+## -----------------------------------------------------------------------
 # 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)\")"
 then
   fail text "This message has been rejected because it has\n\
-            \tpotentially executable content $1\n\
-            \tThis form of attachment has been used by\n\
-             \trecent viruses or other malware.\n\
-            \tIf you meant to send this file then please\n\
-            \tpackage it up as a zip file and resend it."
+            potentially executable content $1\n\
+            This form of attachment has been used by\n\
+             recent viruses or other malware.\n\
+            If you meant to send this file then please\n\
+            package it up as a zip file and resend it."
   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))"
 then
   fail text "This message has been rejected because it has\n\
-            \tpotentially executable content $1\n\
-            \tThis form of attachment has been used by\n\
-             \trecent viruses or other malware.\n\
-            \tIf you meant to send this file then please\n\
-            \tpackage it up as a zip file and resend it."
+            potentially executable content $1\n\
+            This form of attachment has been used by\n\
+             recent viruses or other malware.\n\
+            If you meant to send this file then please\n\
+            package it up as a zip file and resend it."
   seen finish
 endif
 
 
+## -----------------------------------------------------------------------
 # Attempt to catch embedded VBS attachments
 # in emails.   These were used as the basis for 
-# the ILOVEYOU virus and its variants
+# 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;]"
 then
   fail text "This message has been rejected because it has\n\
-            \ta potentially executable attachment $1\n\
-            \tThis form of attachment has been used by\n\
-             \trecent viruses or other malware.\n\
-            \tIf you meant to send this file then please\n\
-            \tpackage it up as a zip file and resend it."
+            a potentially executable attachment $1\n\
+            This form of attachment has been used by\n\
+             recent viruses or other malware.\n\
+            If you meant to send this file then please\n\
+            package it up as a zip file and resend it."
   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;]"
 then
   fail text "This message has been rejected because it has\n\
-            \ta potentially executable attachment $1\n\
-            \tThis form of attachment has been used by\n\
-             \trecent viruses or other malware.\n\
-            \tIf you meant to send this file then please\n\
-            \tpackage it up as a zip file and resend it."
+            a potentially executable attachment $1\n\
+            This form of attachment has been used by\n\
+             recent viruses or other malware.\n\
+            If you meant to send this file then please\n\
+            package it up as a zip file and resend it."
   seen finish
 endif
+## -----------------------------------------------------------------------
+
 
 #### Version history
 #
@@ -150,7 +156,7 @@ endif
 # To install, copy the filter file (with appropriate permissions)
 # to /etc/exim/system_filter.exim and add to your exim config file
 # [location is installation depedant - typicaly /etc/exim/config ]
-# at the top the line:-
+# in the first section the line:-
 #      message_filter = /etc/exim/system_filter.exim
 #      message_body_visible = 5000
 #