File Coverage

blib/lib/Mail/Exim/ACL/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::ACL::Attachments;

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

use 5.016;
use warnings;
use utf8;

our $VERSION = 1.004;

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__