[Mimedefang] Double modifications being made
Robert Covell
rcovell at rolet.com
Thu Jul 18 19:37:01 EDT 2002
Here it is:
# -*- Perl -*-
#***********************************************************************
#
# mimedefang-filter
#
# Suggested minimum-protection filter for Microsoft Windows clients, plus
# SpamAssassin checks if SpamAssassin is installed.
#
# Copyright (C) 2002 Roaring Penguin Software Inc.
#
# This program may be distributed under the terms of the GNU General
# Public License, Version 2, or (at your option) any later version.
#
# $Id: suggested-minimum-filter-for-windows-clients,v 1.42 2002/07/11
20:27:39 dfs Exp $
#***********************************************************************
#***********************************************************************
# Set administrator's e-mail address here. The administrator receives
# quarantine messages and is listed as the contact for site-wide
# MIMEDefang policy. A good example would be 'defang-admin at mydomain.com'
#***********************************************************************
$AdminAddress = 'spamcop at rolet.com';
$AdminName = "Rolet Administration";
#***********************************************************************
# Set the e-mail address from which MIMEDefang quarantine warnings and
# user notifications appear to come. A good example would be
# 'mimedefang at mydomain.com'. Make sure to have an alias for this
# address if you want replies to it to work.
#***********************************************************************
$DaemonAddress = 'spamcop at rolet.com';
#***********************************************************************
# If you set $AddWarningsInline to 1, then MIMEDefang tries *very* hard
# to add warnings directly in the message body (text or html) rather
# than adding a separate "WARNING.TXT" MIME part. If the message
# has no text or html part, then a separate MIME part is still used.
#***********************************************************************
$AddWarningsInline = 0;
#***********************************************************************
# Set various stupid things your mail client does below.
#***********************************************************************
# Set the next one if your mail client cannot handle nested multipart
# messages. DO NOT set this lightly; it will cause action_add_part to
# work rather strangely. Leave it at zero, even for MS Outlook, unless
# you have serious problems.
$Stupidity{"flatten"} = 0;
# Set the next one if your mail client cannot handle multiple "inline"
# parts.
$Stupidity{"NoMultipleInlines"} = 0;
# This procedure returns true for entities with bad filenames.
sub filter_bad_filename ($) {
my($entity) = @_;
my($bad_exts, $re);
# Bad extensions
$bad_exts =
'(ade|adp|bas|bat|chm|cmd|com|cpl|crt|dll|exe|hlp|hta|inf|ini|ins|isp|jse?|l
ib|lnk|mdb|mde|msc|msi|msp|mst|ocx|pcd|pif|reg|scr|sct|shb|shs|sys|url|vb|vb
e|vbs|vxd|wsc|wsf|wsh)';
# Do not allow:
# - curlies
# - bad extensions (possibly with trailing dots) at end or
# followed by non-alphanum
$re = '(\{)|(\})|(\.' . $bad_exts . ')\.*([^-A-Za-z0-9_.]|$)';
return re_match($entity, $re);
}
# Scan for a virus using the first supported virus scanner we find.
sub message_contains_virus () {
return message_contains_virus_avp() if ($Features{'Virus:AVP'});
return message_contains_virus_fprot() if ($Features{'Virus:FPROT'});
return message_contains_virus_fsav() if ($Features{'Virus:FSAV'});
return message_contains_virus_hbedv() if ($Features{'Virus:HBEDV'});
return message_contains_virus_nai() if ($Features{'Virus:NAI'});
return message_contains_virus_nvcc() if ($Features{'Virus:NVCC'});
return message_contains_virus_rav() if ($Features{'Virus:RAV'});
return message_contains_virus_sophie() if ($Features{'Virus:SOPHIE'});
return message_contains_virus_sophos() if ($Features{'Virus:SOPHOS'});
return message_contains_virus_trend() if ($Features{'Virus:TREND'});
return message_contains_virus_filescan() if
($Features{'Virus:FileScan'});
return message_contains_virus_clamav() if ($Features{'Virus:CLAMAV'});
return (wantarray ? (0, 'ok', 'ok') : 0);
}
# Scan for a virus using the first supported virus scanner we find.
sub entity_contains_virus ($) {
my($e) = @_;
return entity_contains_virus_avp($e) if ($Features{'Virus:AVP'});
return entity_contains_virus_fprot($e) if ($Features{'Virus:FPROT'});
return entity_contains_virus_fsav($e) if ($Features{'Virus:FSAV'});
return entity_contains_virus_hbedv($e) if ($Features{'Virus:HBEDV'});
return entity_contains_virus_nai($e) if ($Features{'Virus:NAI'});
return entity_contains_virus_nvcc($e) if ($Features{'Virus:NVCC'});
return entity_contains_virus_rav($e) if ($Features{'Virus:RAV'});
return entity_contains_virus_sophie($e) if
($Features{'Virus:SOPHIE'});
return entity_contains_virus_sophos($e) if
($Features{'Virus:SOPHOS'});
return entity_contains_virus_trend($e) if ($Features{'Virus:TREND'});
return entity_contains_virus_filescan($e) if
($Features{'Virus:FileScan'});
return entity_contains_virus_clamav($e) if
($Features{'Virus:CLAMAV'});
return (wantarray ? (0, 'ok', 'ok') : 0);
}
# sub test {
# my($bad_exts, $re);
# # Bad extensions
# $bad_exts =
'(ade|adp|bas|bat|chm|cmd|com|cpl|crt|dll|exe|hlp|hta|inf|ini|ins|isp|jse?|l
ib|lnk|mdb|mde|msc|msi|msp|mst|ocx|pcd|pif|reg|scr|sct|shb|shs|sys|url|vb|vb
e|vbs|vxd|wsc|wsf|wsh)';
# # Do not allow:
# # - curlies
# # - bad extensions (possibly with trailing dots) at end or
# # followed by non-alphanum
# $re = '(\{)|(\})|(\.' . $bad_exts . ')\.*([^-A-Za-z0-9_.]|$)';
# while(<>) {
# chomp;
# print;
# if ($_ =~ /$re/i) {
# print " MATCHES";
# }
# print("\n");
# }
# }
# test();
#***********************************************************************
# %PROCEDURE: filter_begin
# %ARGUMENTS:
# None
# %RETURNS:
# Nothing
# %DESCRIPTION:
# Called just before e-mail parts are processed
#***********************************************************************
sub filter_begin () {
# ALWAYS drop messages with suspicious chars in headers
if ($SuspiciousCharsInHeaders) {
action_quarantine_entire_message();
action_notify_administrator("Message quarantined because of suspicious
characters in headers");
# Do NOT allow message to reach recipient(s)
return action_discard();
}
# Scan for viruses if any virus-scanners are installed
# my($code, $category, $action) = message_contains_virus();
# $FoundVirus = ($category eq "virus");
}
#***********************************************************************
# %PROCEDURE: filter
# %ARGUMENTS:
# entity -- a Mime::Entity object (see MIME-tools documentation for
details)
# fname -- the suggested filename, taken from the MIME Content-Disposition:
# header. If no filename was suggested, then fname is ""
# ext -- the file extension (everything from the last period in the name
# to the end of the name, including the period.)
# type -- the MIME type, taken from the Content-Type: header.
#
# NOTE: There are two likely and one unlikely place for a filename to
# appear in a MIME message: In Content-Disposition: filename, in
# Content-Type: name, and in Content-Description. If you are paranoid,
# you will use the re_match and re_match_ext functions, which return true
# if ANY of these possibilities match. re_match checks the whole name;
# re_match_ext checks the extension. See the sample filter below for
usage.
# %RETURNS:
# Nothing
# %DESCRIPTION:
# This function is called once for each part of a MIME message.
# There are many action_*() routines which can decide the fate
# of each part; see the mimedefang-filter man page.
#***********************************************************************
sub filter ($$$$) {
my($entity, $fname, $ext, $type) = @_;
return if message_rejected(); # Avoid unnecessary work
# Virus scan
# if ($FoundVirus) {
# my($code, $category, $action);
# $VirusScannerMessages = "";
# ($code, $category, $action) = entity_contains_virus($entity);
# if ($category eq "virus") {
# return action_quarantine($entity, "A known virus was discovered and
deleted. Virus-scanner messages follow:\n$VirusScannerMessages\n\n");
# }
# }
if (filter_bad_filename($entity)) {
action_notify_sender("Your message contained an attachment ($fname)
considered to be potentially harmful. This has been removed and not sent to
the recipient. If the attachment was valid please find other means of
sending the data. You might try utilizing WinZip (PC) or Stuff It(Mac) to
compress the data and resend the email.\n\n-Rolet Email Support");
return action_quarantine($entity, "An attachment named $fname was removed
from this document as it\nconstituted a security hazard. If you require
this document, please contact\nthe sender and arrange an alternate means of
receiving it.\n");
}
# eml is bad if it's not multipart
if (re_match($entity, '\.eml')) {
return action_quarantine($entity, "A non-multipart attachment named $fname
was removed from this document as it\nconstituted a security hazard. If you
require this document, please contact\nthe sender and arrange an alternate
means of receiving it.\n");
}
# Clean up HTML if Anomy::HTMLCleaner is installed.
# if ($Features{"HTMLCleaner"}) {
# if ($type eq "text/html") {
# return anomy_clean_html($entity);
# }
# }
return action_accept();
}
#***********************************************************************
# %PROCEDURE: filter_multipart
# %ARGUMENTS:
# entity -- a Mime::Entity object (see MIME-tools documentation for
details)
# fname -- the suggested filename, taken from the MIME Content-Disposition:
# header. If no filename was suggested, then fname is ""
# ext -- the file extension (everything from the last period in the name
# to the end of the name, including the period.)
# type -- the MIME type, taken from the Content-Type: header.
# %RETURNS:
# Nothing
# %DESCRIPTION:
# This is called for multipart "container" parts such as message/rfc822.
# You cannot replace the body (because multipart parts have no body),
# but you should check for bad filenames.
#***********************************************************************
sub filter_multipart ($$$$) {
my($entity, $fname, $ext, $type) = @_;
if (filter_bad_filename($entity)) {
action_notify_administrator("A MULTIPART attachment of type $type, named
$fname was dropped.\n");
return action_drop_with_warning("An attachment of type $type, named $fname
was removed from this document as it\nconstituted a security hazard. If you
require this document, please contact\nthe sender and arrange an alternate
means of receiving it.\n");
}
# eml is bad if it's not message/rfc822
if (re_match($entity, '\.eml') and ($type ne "message/rfc822")) {
return action_drop_with_warning("A non-message/rfc822 attachment named
$fname was removed from this document as it\nconstituted a security hazard.
If you require this document, please contact\nthe sender and arrange an
alternate means of receiving it.\n");
}
return action_accept();
}
#***********************************************************************
# %PROCEDURE: defang_warning
# %ARGUMENTS:
# oldfname -- the old file name of an attachment
# fname -- the new "defanged" name
# %RETURNS:
# A warning message
# %DESCRIPTION:
# This function customizes the warning message when an attachment
# is defanged.
#***********************************************************************
sub defang_warning ($$) {
my($oldfname, $fname) = @_;
return
"An attachment named '$oldfname' was converted to '$fname'.\n" .
"To recover the file, right-click on the attachment and Save As\n" .
"'$oldfname'\n";
}
# If SpamAssassin found SPAM, append report. We do it as a separate
# attachment of type text/plain
sub filter_end ($) {
my($entity) = @_;
# No sense doing any extra work
return if message_rejected();
# Spam checks if SpamAssassin is installed
if ($Features{"SpamAssassin"}) {
if (-s "./INPUTMSG" < 100*1024) {
# Only scan messages smaller than 100kB. Larger messages
# are extremely unlikely to be spam, and SpamAssassin is
# dreadfully slow on very large messages.
my($hits, $req, $names, $report) = spam_assassin_check();
if ($hits > 9) {
action_quarantine_entire_message();
action_discard();
}
else {
if ($hits >= $req) {
my($score);
if ($hits < 40) {
$score = "*" x int($hits);
} else {
$score = "*" x 40;
}
# We add a header which looks like this:
# X-Spam-Score: 6.8 (******) NAME_OF_TEST,NAME_OF_TEST
# The number of asterisks in parens is the integer part
# of the spam score clamped to a maximum of 40.
# MUA filters can easily be written to trigger on a
# minimum number of asterisks...
action_change_header("Subject", "****POTENTIAL SPAM****$Subject");
action_change_header("X-Spam-Score", "$hits ($score) $names");
# If you find the SA report useful, add it, I guess...
action_add_part($entity, "text/plain", "-suggest",
"$report\n",
"SpamAssassinReport.txt", "inline");
}
}
}
}
}
# DO NOT delete the next line, or Perl will complain.
1;
-----Original Message-----
From: mimedefang-admin at lists.roaringpenguin.com
[mailto:mimedefang-admin at lists.roaringpenguin.com]On Behalf Of David F.
Skoll
Sent: Thursday, July 18, 2002 6:23 PM
To: mimedefang at lists.roaringpenguin.com
Subject: Re: [Mimedefang] Double modifications being made
On Thu, 18 Jul 2002, Robert Covell wrote:
> We just upgraded to mimedefang-2.16 and SA 2.20. When SA identifies a
> message as spam and the score is < 9 or > 5 we modify the subject and
attach
> the report. Only thing is we are getting double entries for everything
> (subject and the report).
Please post your filter.
Thanks,
David.
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