Hacking the Bell HD PVR 9241 : Part 1

Introduction

I have one these old TV PVR that everyone have. You know that mysterious black box that we need under our TV to get our cable subscription? I'm pretity sure that everyone have an old box like that if they did not threw it away. Anyway the point is that  I, myself, do own one that is just getting dust in the storage and I thought that I could do something cool with it. My ultimate goal would be to be able to install a Linux system.

The problem

Surely, the first thing I did was too google it. Sadly there is no one that seems to have done it in the past and there is not much history about a similar project on another model.

Starting the project

So with no clue where to start I decided to open it up, just to see what processor it is running and everything. Here is a picture of the system with the top and front panel removed.

Bell 9241 opened

As you can see, there is a metal holder for the hard drive and a small fan above the motherboard so we remove it and this is what it look like.

Bell 9241 opened without and hard drive cage removed

So now I was quite intrigued by the hard drive as it seems like a standard sata drive. With the help of a screwdriver, i've been able to remove it from his tray.

Hard drive cage

Bell 9241 hard drive

As you can see on the image above it is a standard seagate 320 GB hard drive. It is pretty interesting but we will get back to that later.

Now let's get back to the motherboard. The first interesting thing that i saw on the motherboard was a card reader for maintenance or something like that.

Card slots front panel

Card slots front panel hard metal

Card slots on pcb

I thought that it could be useful to get into a kind of super control mode or something if we are able to crack the card system. But I'm not sure, I have no clear idea of the purpose of this card reader it's just a thought in my head. Anyway let's get into the real shit : finding the cpu. I first thought that it was this chip.

Sti7109VED

So I did a quick google search about this chip only to find out that it is a "Low-cost HDTV set-top box decoder for H.264 and Microsoft WMA9" as you can see by clicking here. So it was obviously not a cpu. Anyway I failed for now to find the cpu but I promise that i'll find it for the next post.

Let's get back to that 320GB hard drive. Obviously it is used to store our tv show, but if we are lucky it's might also be used to store the OS. What is the best way to find out than plugging it directly into a pc motherboard and check it out? That's what I did, so i took an old motherboard that I use for testing purpose, a hard drive with a ubuntu installation, and plugged the famous seagate hard drive. Once in the system, I found out that there was multiple partition in the hard drive, four exactly, but I could only read two of them as you can see on the screenshot below.

Bell Hard Drive partition

As described in this screenshot i could only read one 2.8 GB partition and one 2.0 GB partition. The 2.8 GB partition was pretty much an empty folder while the 2.0 GB had a ton of interesting file that I haven't really took the time to check out right now but I made a copy on a USB hard drive so I could look at it in the comfort of my main pc. I also have uploaded the files to MediaFire so you can download them if you want and help me at analyzing the files, I'm pretty good with computer and all that but there is always gonna be someone better than me. Here is the link. And for the two other partition well i guess that the big one is just for tv show and such and they have used a weird partition to stop piracy (which most people don't care cause they use a capture card :P) and the small one, I have an intuition that it might be the OS itself (which would be goddamn good for us as long as we are able to find how to open it).

Mission for next time

Cause we need a mission

• Finding more details about the cpu.
• Analyzing all the files that I have been able to extract.
• Find the type of partition Bell is using for the two that i was not able to see.
• Possibly open the weird partition.

I hope that you found the start of my research interesting, if you did please make sure to let me know in the comment box below and if you think you could help me let me know by email.

Félix