[LG Optimus G (International)] Andromann:
First things first.

I DID NOT discover this vulnerablity ("daniel.wro" did here and "The_0ne" elaborated the process here ). So all credits to them. I am just writing this post with some screenshots and a video.

Note to the mods : Dear mods, I don't know if this post meets the standards of xda, but since it's not some cracking tutorial but mere exploitation of a poorly coded program, I assumed that it is eligible to be posted here. I hope it doesn't break the rules of this forum. If it did, please DO take it down.

Note to advanced users: Warning! This is a newbie guide. So you'll find the instructions provided here as childish and intimidating.

Sorry about that.

Now, having said that, for those who don't know what the B2B support tool is, it's a tool to allow LG's partners to download all mobile phones files (Service manuals, Flash Files, Softwares, Flashers, etc) from LG's servers.

You could get the client for free but requires 100$ to get access into the database. So, you could either pay and get yourself an account or use this workaround to get into the database without paying up.

This tutorial makes use of programming vulnerablity in the support tool while it communicates with the authentication server.

Prerequisites:

B2B support tool

Get it here

A network traffic monitoring tool (Fiddler/Wireshark/Etherreal/Charles,etc). I will be using Fiddler throughout this tutorial.

Get it here

Syntax view plugin for fiddler

Get it here

Once everything's installed you're ready to go

How it's done?

Step 1: Launch Fiddler (After installing syntax view plugin) and check if automatic breakpoints is disabled under the rules tab.

Step 2: Launch B2B support tool (Installs in C:\ProgramData\LGMOBILEAX by default in win8). Wait for the authentication panel to show up.

Step 3: Once you see the authentication panel, go to fiddler and enable automatic breakpoints before requests.

Step 4: Now go back to the support tool and enter any username and password and press ok.

Step 5: Back to fiddler again. You should see a red colored entry with hostname csmg.lgmobile.com. Select it. On the right pane, select break on response and choose syntax view. You should see something like this.

Step 6: If that's your case too, hit run to completion. Next you should see an entry with host name gsfs-eu.lge.com. Click break on response and should see a message stating user_check status='FAIL' in the syntax view. Now change 'FAIL' to 'OK' and select run to completion.

Run it to completion.

Step 7: You should see 6 more csm.lgmobiles.com requests. Run them all to completion.

Step 8: Once you've done it. The B2B tool's GUI should show up.

You're in!!!

But be careful. Everytime you encounter the hostname gsfs-eu.lge.com (or any authentication server requests), make sure to change FAIL to OK and you're good to go.

I've added a video showing every step involved when you want to download a file. There's nothing uber hacky or anything. It's just keeping your eyes open and making changes wherever necessary.

For video, click here

Note: I would recommend using a download manager with resume ability when downloading larger files. Sometimes, the authentication info might expire (the download can't be resumed). This doesn't mean the link has expired. Just repeat the whole process again till the step where you got the download link. After doing this, just hit resume and the download continues as usual. I don't know if it's related to expiration of cookies with authentication info. But doing this helped me with the downloads.