File Coverage

blib/lib/Mail/Exim/Blacklist/Attachments.pm

Criterion	Covered	Total	%
statement	47	47	100.0
branch	12	14	85.7
condition	1	2	50.0
subroutine	8	8	100.0
pod	2	2	100.0
total	70	73	95.8

package Mail::Exim::Blacklist::Attachments;

# SPDX-License-Identifier: Artistic-1.0-Perl OR GPL-1.0-or-later

use 5.016;
use warnings;
use utf8;

our $VERSION = 2.000;

use Exporter qw(import);
use IO::Uncompress::Unzip;

our @EXPORT_OK = qw(check_filename check_zip);

# https://docs.microsoft.com/en-us/deployoffice/compat/office-file-format-reference
# https://en.wikipedia.org/wiki/List_of_Microsoft_Office_filename_extensions
our %MACRO_ENABLED = (
  doc  => 'Word Document',
  docb => 'Word Document',
  docm => 'Word Document',
  dot  => 'Word Template',
  dotm => 'Word Template',
  pot  => 'PowerPoint Template',
  potm => 'PowerPoint Template',
  ppa  => 'PowerPoint Add-in',
  ppam => 'PowerPoint Add-in',
  pps  => 'PowerPoint Slide Show',
  ppsm => 'PowerPoint Slide Show',
  ppt  => 'PowerPoint Presentation',
  pptm => 'PowerPoint Presentation',
  sldm => 'PowerPoint Slide',
  vsd  => 'Visio Drawing File',
  vsdm => 'Visio Drawing File',
  vss  => 'Visio Stencil File',
  vssm => 'Visio Stencil File',
  vst  => 'Visio Drawing Template',
  vstm => 'Visio Drawing Template',
  xla  => 'Excel Add-in',
  xlam => 'Excel Add-in',
  xlm  => 'Excel Macro',
  xls  => 'Excel Spreadsheet',
  xlsb => 'Excel Spreadsheet',
  xlsm => 'Excel Spreadsheet',
  xlt  => 'Excel Spreadsheet Template',
  xltm => 'Excel Spreadsheet Template',
  xlw  => 'Excel Workspace',
);

# https://support.office.com/en-us/article/blocked-attachments-in-outlook-434752e1-02d3-4e90-9124-8b81e49a8519
our %BLOCKED_BY_OUTLOOK = (
  ade           => 'Access Project Extension',
  adp           => 'Access Project',
  app           => 'Executable Application',
  asp           => 'Active Server Page',
  aspx          => 'Active Server Page Extended',
  asx           => 'ASF Redirector file',
  bas           => 'BASIC Source Code',
  bat           => 'Batch Processing',
  cer           => 'Internet Security Certificate File',
  chm           => 'Compiled HTML Help',
  cmd           => 'Command File',
  cnt           => 'Microsoft Help Workshop Application',
  com           => 'Command',
  cpl           => 'Windows Control Panel Extension',
  crt           => 'Certificate File',
  csh           => 'csh Script',
  der           => 'DER Encoded X509 Certificate File',
  diagcab       => 'Microsoft Support diagnostic tools',
  exe           => 'Executable File',
  fxp           => 'FoxPro Compiled Source',
  gadget        => 'Windows Vista gadget',
  grp           => 'Microsoft program group',
  hlp           => 'Windows Help File',
  hpj           => 'AppWizard Help project',
  hta           => 'Hypertext Application',
  htc           => 'HTML component file',
  inf           => 'Information or Setup File',
  ins           => 'IIS Internet Communications Settings',
  isp           => 'IIS Internet Service Provider Settings',
  its           => 'Internet Document Set',
  jar           => 'Java Archive',
  jnlp          => 'Java Network Launch Protocol',
  js            => 'JavaScript Source Code',
  jse           => 'JScript Encoded Script File',
  ksh           => 'UNIX Shell Script',
  lnk           => 'Windows Shortcut File',
  mad           => 'Access Module Shortcut',
  maf           => 'Access',
  mag           => 'Access Diagram Shortcut',
  mam           => 'Access Macro Shortcut',
  maq           => 'Access Query Shortcut',
  mar           => 'Access Report Shortcut',
  mas           => 'Access Stored Procedures',
  mat           => 'Access Table Shortcut',
  mau           => 'Media Attachment Unit',
  mav           => 'Access View Shortcut',
  maw           => 'Access Data Access Page',
  mcf           => 'Media Container Format',
  mda           => 'Access Add-in',
  mdb           => 'Access Application',
  mde           => 'Access MDE Database File',
  mdt           => 'Access Add-in Data',
  mdw           => 'Access Workgroup Information',
  mdz           => 'Access Wizard Template',
  msc           => 'Microsoft Management Console Snap-in Control File',
  msh           => 'Microsoft Shell',
  msh1          => 'Microsoft Shell',
  msh2          => 'Microsoft Shell',
  mshxml        => 'Microsoft Shell',
  msh1xml       => 'Microsoft Shell',
  msh2xml       => 'Microsoft Shell',
  msi           => 'Windows Installer File',
  msp           => 'Windows Installer Update',
  mst           => 'Windows SDK Setup Transform Script',
  msu           => 'Windows Update file',
  ops           => 'Office Profile Settings File',
  osd           => 'Open Software Description ',
  pcd           => 'Visual Test',
  pif           => 'Windows Program Information File',
  pl            => 'Perl script',
  plg           => 'Developer Studio Build Log',
  prf           => 'Windows System File',
  prg           => 'Program File',
  printerexport => 'Printer backup file',
  ps1           => 'Windows PowerShell',
  ps1xml        => 'Windows PowerShell',
  ps2           => 'Windows PowerShell',
  ps2xml        => 'Windows PowerShell',
  psc1          => 'Windows PowerShell',
  psc2          => 'Windows PowerShell',
  psd1          => 'Windows PowerShell',
  psdm1         => 'Windows PowerShell',
  pst           => 'Outlook Personal Folder File',
  py            => 'Python script',
  pyc           => 'Python script',
  pyo           => 'Python script',
  pyw           => 'Python script',
  pyz           => 'Python script',
  pyzw          => 'Python script',
  reg           => 'Registry Data File',
  scf           => 'Windows Explorer Command',
  scr           => 'Windows Screen Saver',
  sct           => 'Windows Script Component',
  shb           => 'Windows Shortcut into a Document',
  shs           => 'Shell Scrap Object File',
  theme         => 'Desktop theme file settings',
  tmp           => 'Temporary File/Folder',
  url           => 'Internet Location',
  vb            => 'VBScript File or Any Visual Basic Source',
  vbe           => 'VBScript Encoded Script File',
  vbp           => 'Visual Basic project file',
  vbs           => 'VBScript File',
  vhd           => 'Virtual Hard Disk',
  vhdx          => 'Virtual Hard Disk Extended',
  vsmacros      => 'Visual Studio .NET Binary-based Macro Project',
  vsw           => 'Visio Workspace File',
  webpnp        => 'Internet printing file',
  website       => 'Pinned site shortcut from Internet Explorer',
  ws            => 'Windows Script File',
  wsc           => 'Windows Script Component',
  wsf           => 'Windows Script File',
  wsh           => 'Windows Script Host Settings File',
  xbap          => 'Browser applications',
  xll           => 'Excel Add-in',
  xnk           => 'Exchange Public Folder Shortcut',
);

# File associations from 7-Zip and others
our %ARCHIVES = (
  '7z'     => '7-Zip Archive',
  ace      => 'ACE File',
  arj      => 'ARJ File',
  bz2      => 'bzip2 File',
  bzip2    => 'bzip2 File',
  cab      => 'Windows Cabinet File',
  cpio     => 'CPIO Archive',
  deb      => 'Debian Package',
  dmg      => 'Disk Image',
  esd      => 'Disk Image',
  fat      => 'Zip Archive',
  gz       => 'gzip File',
  gzip     => 'gzip File',
  hfs      => 'Disk Image',
  iso      => 'Disk Image',
  lha      => 'LHA File',
  lzh      => 'LZH File',
  lzma     => 'LZMA File',
  ntfs     => 'Disk Image',
  rar      => 'RAR Archive',
  rpm      => 'RPM File',
  sfx      => 'Self-extracting Archive',
  squashfs => 'Disk Image',
  swm      => 'Disk Image',
  tar      => 'tar Archive',
  taz      => 'tar Archive',
  tbz      => 'tar Archive',
  tbz2     => 'tar Archive',
  tgz      => 'tar Archive',
  tpz      => 'tar Archive',
  txz      => 'tar Archive',
  uue      => 'uuencoded File',
  wim      => 'Disk Image',
  xar      => 'XAR File',
  xz       => 'XZ File',
  z        => 'gzip File',
  zip      => 'Zip Archive',
);

our %BLOCKLIST = (%MACRO_ENABLED, %BLOCKED_BY_OUTLOOK, %ARCHIVES);

sub check_filename {
  my $filename = shift;

  my $extension = q{};
  if ($filename =~ m{[.]\h*([^.]+)\z}) {
    $extension = lc $1;
  }

  if (exists $BLOCKLIST{$extension}) {
    return 'blocked';
  }

  # Reject split archives like "001" and "r01".
  if ($extension =~ m{\A[r\d]\d{2,}\z}) {
    return 'blocked';
  }

  return 'ok';
}

sub _get_filename {
  my $zip = shift;

  my $filename;

  my $header = eval { $zip->getHeaderInfo };
  if (defined $header) {
    $filename = $header->{Name};
  }

  return $filename;
}

sub check_zip {
  my $input = shift;

  my $result = 'blocked';

  my $zip = eval { IO::Uncompress::Unzip->new($input) };
  if (defined $zip) {
    my $status = 1;
    STREAM:
    while ($status > 0) {
      my $filename = _get_filename($zip);
      if (defined $filename) {
        $result = check_filename($filename);
      }
      else {
        $result = 'blocked';
      }
      if ($result ne 'ok') {
        last STREAM;
      }
      $status = eval { $zip->nextStream } // -1;
    }
    $zip->close;
  }

  return $result;
}

1;
__END__