Hello everyone, I just wanted to discuss some vulnerability I found and exploited for GOODNESS .. just so that SCRIPT KIDIES won’t attack your home/business network .php
Well, in Algeria the main ISP ( Algerie Telecom ) provide you with a router when you pay for an internet plan. So you can conclude that every subscriber is using that router . TD-W8951ND is one of them, I did some ip scanning and I found that every router is using ZYXEL embedded firmware.python
Let’s download an update and take a look at it and try to find some vulnerabilities. ( http://www.tp-link.com/Resources/software/TD-W8951ND_V3.0_110729_FI.rar )git
The ras file is in LIF format !! …
Hmmm let’s put that file for Binwalk test for God’s sake ! ( check :http://code.google.com/p/binwalk/wiki/Installation for more informations on how to install it ).github
This is what Binwalk told me about that file : web
You can clearly see and confirm that the router is using zynos firmware. We can also see that there is two blocks of LZMA compressed data … let’s extract them and have a look. shell
The problem is that when I tried to decompress the two blocks I get an error : 」 Compressed data is corrupt 「ide
Hmm, first the 「ras」 file was in LIF format .. and now the lzma compress blocks are corrupted !!
I googled this and tried to find a solution for this, FOUND NOTHING . How am I going to solve this ??
One idea came in my mind .. 「Strings」 command and here is what I got :oop
Aaaah ! so the blocks aren’t compressed with LZMA or anything ! and the whole 「ras」 firmware file is just big chunk of data in clear text.
Ok, let’s try and find some useful STRINGS …post
After some time searching 「I」 didn’t find the useful thing that will help us find vulnerabilities on the firmware !!ui
I didn’t give up …
I just was thinking and questioning :
Me: What do you want from this firmware file !
Me: I want to find remote vulnerabilities that will help me extract the 「admin」 password.
Me: Does the web interface let you save the current configuration ?
Me: yes !!
Me: Is the page password protected ?
Me: No !!! I tired to access that page on a different IP and it didn’t require a passowrd !
Ok, enough questions haha ..
Now, when I activated TamperData and clicked 「ROMFILE SAVE」  I’ve found out that the rom-0 file is located on 「IP/rom-0″ and the directory isn’t password protected or anything.
So we are able to download the configuration file which contains the 「admin」 password. I took a look at rom-0 file and couldn’t figure out how to reverse-engineer it, and when you don’t know something it’s not a shame to ask for help .. and that’s what I did !
I contacted 「Craig」 from devttys0.com, he is an expect when it comes to hacking embdded devices . He’s a great guy and he replied to my email and pointed me to http://50.57.229.26/zynos.phpwhich is a free rom-0 file decompressor .
When you upload and submit the rom-0 file there, the php page replies back with the configuration in clear text ( INCLUDING THE PASSWORD ) .
So what i need to do now is to automate the process of :
Download rom-0 file.
Upload it to http://50.57.229.26/zynos.php
get the repy back and extract the admin password from it.
loop this process to a range of ip addresses.
And that’s exactly what I did, I opened an OLD OLD poc python script of mine that accessed routers via telnet using the default passwords. So what I just need to do now is to add some functionality to it.
Well I thought about  this, and I’m posting this script online ONLY FOR EDUCATIONAL PURPOSES.
You can find the scripts here : https://github.com/MrNasro/zynos-attacker/
Demo :
PS : I OWN ALL THE IP RANGE I WAS SCANNING 」 FOR SURE 「
Now ! how do you prevent attackers from downloading your rom-0 configuration file and manipulating your router ? This is pretty simple if you think about it ..
You just have to forward port 80 on the router to and inused IP address on your network :
THATS ALL, or if you want to play a little with attackers that are using scripts too .. just forward port 80 to you local http server and put a LARGE file in the root directory and name it rom-0 .. just let them download like 1GB rom-0 file haha haha .. I have also automated the process of port forwarding and I’m running the scripts daily just to prevent hackers from attacking weak users …
In the next post I’ll demonstrate how would a malicious hacker exploit this to hack TONS of networks and get a meterpreter/reverse_shell on every PC on the target network ..
Hope you enjoyed this analysis, if you have anything to add or any questions to ask don’t hesitate to contact me ! BE THEIR HERO, HAPPY HACKING