changeset 142:dae1088dd218 puppet-3.6

Add OLE detection to SpamAssassin without ClamAV Note: currently subject to https://github.com/JonathanThorpe/spamassassin-vba-macro/issues/15
author IBBoard <dev@ibboard.co.uk>
date Thu, 09 Feb 2017 20:54:30 +0000
parents ce6aafd0880b
children 58d98753e5f9
files common/ole2macro.cf common/spamassassin-vba-macro-master/LICENSE common/spamassassin-vba-macro-master/README.md common/spamassassin-vba-macro-master/ole2macro.pm manifests/templates.pp
diffstat 5 files changed, 459 insertions(+), 0 deletions(-) [+]
line wrap: on
line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/common/ole2macro.cf	Thu Feb 09 20:54:30 2017 +0000
@@ -0,0 +1,6 @@
+# Run VBA Macro checks without ClamAV
+loadplugin OLE2Macro ole2macro.pm
+
+body MICROSOFT_OLE2MACRO eval:check_microsoft_ole2macro()
+describe MICROSOFT_OLE2MACRO Has an attachment that contains an OLE2 Macro
+score MICROSOFT_OLE2MACRO 4
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/common/spamassassin-vba-macro-master/LICENSE	Thu Feb 09 20:54:30 2017 +0000
@@ -0,0 +1,202 @@
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/common/spamassassin-vba-macro-master/README.md	Thu Feb 09 20:54:30 2017 +0000
@@ -0,0 +1,34 @@
+# SpamAssassin Plugin for detecting VBA/OLE2 Macros in Word/Excel Documents
+
+SpamAssassin plugin for detecting VBA macros in Microsoft Office Documents, including those contained within ZIP archives.
+
+## Motivation ##
+
+This plugin was built in response to increasing phishing/malware found in Microsoft Word and Excel Documents that seems to get past the majority of Virus Scanners when new waves first start.
+
+Most installations running SpamAssassin also run ClamAV and while ClamAV has a configuration option to block OLE2Macros (OLE2BlockMacros), this doesn't work well in practice because surprisingly, some people still send emails with legitimate VBA Macros.
+
+This plugin is designed to crudely (but so far, effectively) identify VBA/OLE2 Macros embedded in Microsoft Word and Excel Documents by looking at a signature in the file only present when VBA Macros are used and allows you to assign a configurable score to these documents such that other factors can contribute to an overall score before considering the email spam.
+
+## Dependencies ##
+
+This module requires the following Perl modules to be installed:
+* IO::Uncompress::Unzip
+* IO::Scalar
+
+In order to detect VBA/Macro-enabled formats (i.e. .docm) disguised as classic Microsoft Office formats by renaming the files, it's recommended you also install:
+* File::MimeInfo::Magic
+
+## Installation ##
+
+Simply place the following in your SpamAssassin configuration file along with the ole2macro.pm in a directory where SpamAssassin is able to find it (i.e. /etc/spamassassin). For instance ```/etc/spamassassin/conf.d/90_ole2macro.cf```
+
+```
+loadplugin OLE2Macro ole2macro.pm
+
+body MICROSOFT_OLE2MACRO eval:check_microsoft_ole2macro()
+describe MICROSOFT_OLE2MACRO Has an attachment that contains an OLE2 Macro
+score MICROSOFT_OLE2MACRO 4
+```
+
+In most cases, you will want to adjust the score accordingly, however, with a cut-off score of 5.5, 4.0 as described above has worked well in a production environment with diverse users.
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/common/spamassassin-vba-macro-master/ole2macro.pm	Thu Feb 09 20:54:30 2017 +0000
@@ -0,0 +1,207 @@
+# <@LICENSE>
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to you under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# </@LICENSE>
+
+=head1 NAME
+
+OLE2Macro - Look for Macro Embedded Microsoft Word and Excel Documents
+
+=head1 SYNOPSIS
+
+loadplugin     ole2macro.pm
+body MICROSOFT_OLE2MACRO eval:check_microsoft_ole2macro()
+score MICROSOFT_OLE2MACRO 4
+
+=head1 DESCRIPTION
+
+Detects embedded OLE2 Macros embedded in Word and Excel Documents. Based on:
+https://blog.rootshell.be/2015/01/08/searching-for-microsoft-office-files-containing-macro/
+
+10/12/2015 - Jonathan Thorpe - jthorpe@conexim.com.au
+
+=back
+
+=cut
+
+package OLE2Macro;
+
+use Mail::SpamAssassin::Plugin;
+use Mail::SpamAssassin::Logger;
+use Mail::SpamAssassin::Util;
+use IO::Uncompress::Unzip;
+use IO::Scalar;
+
+use strict;
+use warnings;
+use bytes;
+use re 'taint';
+
+use vars qw(@ISA);
+@ISA = qw(Mail::SpamAssassin::Plugin);
+
+#File types and markers
+my $match_types = qr/(?:xls|xlt|pot|ppt|pps|doc|dot)$/;
+
+#Microsoft OOXML-based formats with Macros
+my $match_types_xml = qr/(?:xlsm|xltm|xlsb|potm|pptm|ppsm|docm|dotm)$/;
+
+#Markers in the order in which they should be found.
+my @markers = ("\xd0\xcf\x11\xe0", "\x00\x41\x74\x74\x72\x69\x62\x75\x74\x00");
+
+# limiting the number of files within archive to process
+my $archived_files_process_limit = 3;
+# limiting the amount of bytes read from a file
+my $file_max_read_size = 102400;
+# limiting the amount of bytes read from an archive
+my $archive_max_read_size = 1024000;
+
+# limiting the amount of bytes read from a file to determine MIME type
+my $mime_max_read_size = 8;
+
+
+my $has_mimeinfo = 0;
+eval('use File::MimeInfo::Magic');
+if(!$@){
+    $has_mimeinfo = 1;
+}
+
+# constructor: register the eval rule
+sub new {
+    my $class = shift;
+    my $mailsaobject = shift;
+
+   # some boilerplate...
+    $class = ref($class) || $class;
+    my $self = $class->SUPER::new($mailsaobject);
+    bless ($self, $class);
+
+    $self->register_eval_rule("check_microsoft_ole2macro");
+
+    return $self;
+}
+
+sub check_microsoft_ole2macro {
+    my ($self, $pms) = @_;
+
+    _check_attachments(@_) unless exists $pms->{nomacro_microsoft_ole2macro};
+    return $pms->{nomacro_microsoft_ole2macro};
+}
+
+sub _match_markers {
+    my ($data) = @_;
+
+    my $matched=0;
+    foreach(@markers){
+        if(index($data, $_) > -1){
+            $matched++;
+        } else {
+            last;
+        }
+    }
+
+    return $matched == @markers;
+}
+
+sub _is_zip {
+    my ($name, $part) = @_;
+
+    if ($has_mimeinfo){
+        my $contents_scalar = new IO::Scalar \$part->decode($mime_max_read_size);
+        my $mime_type = File::MimeInfo::Magic::magic($contents_scalar);
+        return($mime_type eq "application/zip");
+    }else{
+        return($name =~ /(?:zip)$/);
+    }
+}
+
+sub _check_attachments {
+    my ($self, $pms) = @_;
+
+    my $processed_files_counter = 0;
+    $pms->{nomacro_microsoft_ole2macro} = 0;
+
+    foreach my $p ($pms->{msg}->find_parts(qr/./, 1)) {
+        my ($ctype, $boundary, $charset, $name) =
+        Mail::SpamAssassin::Util::parse_content_type($p->get_header('content-type'));
+
+
+        $name = lc($name || '');
+        if ($name =~ $match_types) {
+            my $contents = $p->decode($file_max_read_size);
+            if(_match_markers($contents)){
+                $pms->{nomacro_microsoft_ole2macro} = 1;
+                last;
+            }
+        }
+
+        if (_is_zip($name, $p)) {
+            my $contents = $p->decode($archive_max_read_size);
+            my $z = new IO::Uncompress::Unzip \$contents;
+
+            my $status;
+            my $buff;
+            my $zip_fn;
+
+            if (defined $z) {
+                for ($status = 1; $status > 0; $status = $z->nextStream()) {
+                    $zip_fn = lc $z->getHeaderInfo()->{Name};
+
+                    #Parse these first as they don't need handling of the contents.
+                    if ($zip_fn =~ $match_types_xml) {
+                        $pms->{nomacro_microsoft_ole2macro} = 1;
+                        last;
+                    } elsif ($zip_fn =~ $match_types or $zip_fn eq "[content_types].xml") {
+                        $processed_files_counter += 1;
+                        if ($processed_files_counter > $archived_files_process_limit) {
+                            dbg( "Stopping processing archive on file ".$z->getHeaderInfo()->{Name}.": processed files count limit reached\n" );
+                            last;
+                        }
+                        my $attachment_data = "";
+                        my $read_size = 0;
+                        while (($status = $z->read( $buff )) > 0) {
+                            $attachment_data .= $buff;
+                            $read_size += length( $buff );
+                            if ($read_size > $file_max_read_size) {
+                                dbg( "Stopping processing file ".$z->getHeaderInfo()->{Name}." in archive: processed file size overlimit\n" );
+                                last;
+                            }
+                        }
+
+                        #OOXML format
+                        if($zip_fn eq "[content_types].xml"){
+                            if($attachment_data =~ /ContentType=["']application\/vnd.ms-office.vbaProject["']/i){
+                                $pms->{nomacro_microsoft_ole2macro} = 1;
+                                last;
+                            }
+                        }else{
+                            if (_match_markers( $attachment_data )) {
+                                $pms->{nomacro_microsoft_ole2macro} = 1;
+                                last;
+                            }
+                        }
+                    }
+                }
+            }else{
+                dbg( "Unable to open ZIP file\n" );
+            }
+        } elsif ($name =~ $match_types_xml) {
+            $pms->{nomacro_microsoft_ole2macro} = 1;
+            last;
+        }
+    }
+}
+
+1;
--- a/manifests/templates.pp	Wed Jan 18 21:13:20 2017 +0000
+++ b/manifests/templates.pp	Thu Feb 09 20:54:30 2017 +0000
@@ -656,6 +656,16 @@
 		source => 'puppet:///private/postfix/amavisd.conf',
 		tag => 'av',
 	}
+	file { '/etc/mail/spamassassin/ole2macro.cf':
+		ensure => present,
+		source => 'puppet:///common/ole2macro.cf',
+		tag => 'av',
+	}
+	file { '/etc/mail/spamassassin/ole2macro.pm':
+		ensure => present,
+		source => 'puppet:///common/spamassassin-vba-macro-master/ole2macro.pm',
+		tag => 'av',
+	}
 	Package<| tag == 'av' |> -> File<| tag == 'av' |>
 	File<| tag == 'av' |> {
 		notify => Service['amavisd'],