[Mimedefang] what am I doing wrong?
Douglas J Hunley
doug at hunley.homeip.net
Tue Jun 18 21:18:20 EDT 2002
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I'm getting a significant amount of 'filter timed out' messages. my system
load is fine, so it's my filter. ideas anyone?
- --
Douglas J Hunley (doug at hunley.homeip.net) - Linux User #174778
Admin: Linux StepByStep - http://www.linux-sxs.org
and http://jobs.linux-sxs.org
It's overkill, of course. But you can never have too much overkill.
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# -*- Perl -*-
#***********************************************************************
#
# mimedefang-filter
#
#***********************************************************************
#***********************************************************************
# 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 = 'defang-admin at linux-sxs.org';
$AdminName = "MIMEDefang Administrator";
#***********************************************************************
# 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 = 'mimedefang at linux-sxs.org';
#***********************************************************************
# 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 = 1;
#***********************************************************************
# 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?|lib|lnk|mdb|mde|msc|msi|msp|mst|ocx|pcd|pif|reg|scr|sct|shb|shs|sys|url|vb|vbe|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_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 ($Features{'Virus:FileScan'});
return (wantarray ? (0, 'ok', 'ok') : 0);
}
# Scan for a virus using the first supported virus scanner we find.
sub entity_contains_virus ($) {
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 ($Features{'Virus:NAI'});
return entity_contains_virus_rav($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 (wantarray ? (0, 'ok', 'ok') : 0);
}
#***********************************************************************
# %PROCEDURE: filter_begin
# %ARGUMENTS:
# None
# %RETURNS:
# Nothing
# %DESCRIPTION:
# Called just before e-mail parts are processed
#***********************************************************************
sub filter_begin () {
# Scan for viruses if any virus-scanners are installed
$VirusScannerMessages = "";
my($code, $category, $action) = message_contains_virus();
$VirusScannerMessages =~ s/^\/var.*\n//g;
$VirusScannerMessages =~ s/^\s+//;
if ($action eq "quarantine") {
action_bounce("File::Scan detected a VIRUS in your email. Rejected.");
my $message =
" VIRUS ALERT\n\n" .
"Our virus scanner found a VIRUS in your email to " .
"@Recipients.\n\nWe advise you to check your computer for " .
"viruses. We recommend the\nlatest version of the " .
"following anti-virus software:\n\n" .
" AVG http://www.grisoft.com/\n" .
" (it's free for home use)\n" .
"\n BE SURE TO UPDATE YOUR ANTI-VIRUS SOFTWARE WITH " .
"THE LATEST VIRUS DEFINITIONS ROUTINELY.\n\nOur virus " .
"scanner reported the following:\n\n$VirusScannerMessages\n";
if (open(IN, "<HEADERS")) {
$message .="\n-----Original Message Headers-----\n";
while (<IN>) {
$message .= $_;
}
close(IN);
}
action_notify_sender($message);
action_notify_administrator("-----Original Message-----\n" .
"From: $DaemonName <$DaemonAddress>\n" .
"Sent: " . localtime() . "\n" .
"To: $Sender\n" .
"Subject: MIMEDefang Notification.\n\n" .
$message);
add_recipient($Administrator);
} else {
action_change_header("X-Virus-Scanned", "$action");
}
# check for Spam if SpamAssassin is installed
if ($Features{"SpamAssassin"}) {
($hits, $req, $names, $report) = spam_assassin_check();
# my($hits, $req, $names, $report) = spam_assassin_check();
if ($hits >=10) {
action_quarantine_entire_message();
action_bounce("SpamAssassin says this email is SPAM. Rejected.");
}
}
}
#***********************************************************************
# %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 ($$$$) {
my($entity, $fname, $ext, $type) = @_;
return if message_rejected(); # Avoid unnecessary work
if (filter_bad_filename($entity)) {
return action_quarantine($entity, "An attachment named $fname was removed from this document as it\nconstituted a security hazard. If you require this document, please contact\nthe sender and arrange an alternate means of receiving it.\n");
}
# eml is bad if it's not multipart
if (re_match($entity, '\.eml')) {
return action_quarantine($entity, "A non-multipart attachment named $fname was removed from this document as it\nconstituted a security hazard. If you require this document, please contact\nthe sender and arrange an alternate means of receiving it.\n");
}
return action_accept();
}
#***********************************************************************
# %PROCEDURE: filter_multipart
# %ARGUMENTS:
# entity -- a Mime::Entity object (see MIME-tools documentation for details)
# fname -- the suggested filename, taken from the MIME Content-Disposition:
# header. If no filename was suggested, then fname is ""
# ext -- the file extension (everything from the last period in the name
# to the end of the name, including the period.)
# type -- the MIME type, taken from the Content-Type: header.
# %RETURNS:
# Nothing
# %DESCRIPTION:
# This is called for multipart "container" parts such as message/rfc822.
# You cannot replace the body (because multipart parts have no body),
# but you should check for bad filenames.
#***********************************************************************
sub filter_multipart ($$$$) {
my($entity, $fname, $ext, $type) = @_;
if (filter_bad_filename($entity)) {
action_notify_administrator("A MULTIPART attachment of type $type, named $fname was dropped.\n");
return action_drop_with_warning("An attachment of type $type, named $fname was removed from this document as it\nconstituted a security hazard. If you require this document, please contact\nthe sender and arrange an alternate means of receiving it.\n");
}
# eml is bad if it's not message/rfc822
if (re_match($entity, '\.eml') and ($type ne "message/rfc822")) {
return action_drop_with_warning("A non-message/rfc822 attachment named $fname was removed from this document as it\nconstituted a security hazard. If you require this document, please contact\nthe sender and arrange an alternate means of receiving it.\n");
}
return action_accept();
}
#***********************************************************************
# %PROCEDURE: defang_warning
# %ARGUMENTS:
# oldfname -- the old file name of an attachment
# fname -- the new "defanged" name
# %RETURNS:
# A warning message
# %DESCRIPTION:
# This function customizes the warning message when an attachment
# is defanged.
#***********************************************************************
sub defang_warning ($$) {
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";
}
sub filter_end ($) {
my($entity) = @_;
# No sense doing any extra work
return if message_rejected();
# marking mail with SpamAssassin info
if ($hits >= $req) {
action_change_header("X-Spam-Warning","SpamAssassin says this message is SPAM");
action_change_header("X-Spam-Status","Yes, hits=$hits, required=$req");
my $graph = '*' x ($hits > 50 ? 50 : int($hits));
action_change_header("X-Spam-Level","$graph $hits $graph");
$Boilerplate = $report;
} else {
action_change_header("X-Spam-Status","No, hits=$hits, required=$req");
}
}
# DO NOT delete the next line, or Perl will complain.
1;
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