Thanks Steffen,
I now call the subroutine using if (contains_office_macros($entity))...
I made the changes to the sub contains_office_macros below, I hope
that these changes are correct.
Does the sub contains_office_macros need be called by sub
filter_multipart only or
does it need to be called by the sub filter as well?
sub filter_multipart {
my($entity, $fname, $ext, $type) = @_;
return if message_rejected(); # Avoid unnecessary work
if (contains_office_macros($entity)) {
action_notify_administrator("An attachment of type $type, sent by
$Sender for $Recip named $fname contains macros.\n");
my $subject = $entity->head->get('Subject',0);
action_change_header('Subject', "[Warning Attachment $fname
contains macros (possible virus):] $Subject");
}
# Block message/partial parts
if (lc($type) eq "message/partial") {
md_graphdefang_log('message/partial');
action_bounce("MIME type message/partial not accepted here");
return;
}
return action_accept();
}
# These markers were documented at:
#
http://blog.rootshell.be/2015/01/08/searching-for-microsoft-office-files-containing-macro/
# as of 2015-01-15
# $entity is a MIME::Entity that's the parsed message
my $marker1 = "\xd0\xcf\x11\xe0";
my $marker2 = "\x00\x41\x74\x74\x72\x69\x62\x75\x74\x00";
sub contains_office_macros
{
my ($entity) = @_;
my @parts = $entity->parts();
if (scalar(@parts) > 0) {
return 0;
}
my $is_msoffice_extension = 0;
foreach my $attr_name (qw( Content-Disposition.filename
Content-Type.name) ) {
my $possible = $entity->head->mime_attr($attr_name);
$possible = decode_mimewords($possible);
if ($possible =~ /\.(doc|docx)$/i) {
$is_msoffice_extension = 1;
last;
}
}
return 0 unless $is_msoffice_extension;
return 0 unless defined($entity->bodyhandle) &&
defined($entity->bodyhandle->path);
my $fp;
if (!open($fp, '<:raw', $entity->bodyhandle->path)) {
return 0;
}
my $contents;
{
local $/;
$contents = <$fp>;
close($fp);
}
if (index($contents, $marker1) > -1 &&
index($contents, $marker2) > -1) {
return 1;
}
return 0;
}
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