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Turning a TV set-top box into a Linux computer (2022)

zeus.ugent.be

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Re: Turning a TV set-top box into a Linux computer (2022)

#101

Post by progman32 »

I started down a similar path for a Lorex NVR, amusingly it brings out its serial port to a physical DB9 on the back. Trivial to get it into the uBoot prompt and start dumping its flash. Annoyingly it has a hardware watchdog that reset the machine every minute or so unless it's in the OS. I didn't feel like figuring it out so I wrote a quick script that dumped a few hundred K, waited for machine reset, re-entered u-boot, and kept dumping.

Ultimately I decided to work on something else as I have plenty of more interesting hardware hacking projects to work on, but it was fun practice to overcome the watchdog.

Re: Turning a TV set-top box into a Linux computer (2022)

#102

Post by redfast00 »

n8henrie wrote: post #91
redfast00 wrote: post #22

Earlier quoted context omitted.

Mainly by looking at what addresses the original bootloader loads them into. The addresses don't matter too much, as long as you load them into valid memory, since for most you pass a reference to them anyway in later steps.

Thanks for your response! I'm a hobbyist that's been tinkering with uboot now and again for years and can never figure out the right addresses for stuff, or where / how to learn this. I assume this memory is subsequently released for the OS? Or does the OS just work around it? Are you hobbling your runtime experience in some way if you load to the wrong address?

This is raw memory, so the concept of malloc/free does not really exist: the OS will just overwrite the data.

I think (not entirely sure) that the kernel gets relocated to a more or less fixed address in memory anyway, this won't affect your runtime experience.

Re: Turning a TV set-top box into a Linux computer (2022)

#103

Post by anonuser123456 »

BizarroLand wrote: post #74
NegativeK wrote: post #68

Earlier quoted context omitted.

Given how quickly support is dropped for consumer electronics, not opening up access to them is unacceptable. And that isn't really addressing the fact that many companies don't have the funding or the will to secure these devices.

I mean, if nothing else when the device reaches EOL what would it hurt to release a bootloader unlock?

>would it hurt to release a bootloader unlock?

In cases I am familiar with, you would need the sign off of 4 separate companies. I’m 99% certain one of them would outright refuse. I’m also 99% certain the others would be ambivalent and it would fall to the bottom of a bottomless queue.

Re: Turning a TV set-top box into a Linux computer (2022)

#104

Post by The_SamminAter »

redfast00 wrote: post #11

author here, surprised to see this on HN. If you have any questions, don't hesitate to ask :)

I’m about to attempt to do something similar on Deco routers, using [this](https://blog.keane.space/tp-link-deco-m5-hardware-hacking.ht...) as a base, but have never wired serial to usb manually before. My main question is how do you use a multimeter to tell which pad is which?

Great article!

Re: Turning a TV set-top box into a Linux computer (2022)

#105

Post by tinus_hn »

avidiax wrote: post #88
tinus_hn wrote: post #40

Has anyone ever tried to find out how one can connect to the TV servers and how the DRM works? In the EU you’d be allowed to get the keys from the provider.

Sometimes it is just an app that knows where the streams are, and sometimes there is a devices attestation certificate burned into a TPM. The latter you are probably not going to hack, and even if you could, the various pirate IPTV providers will provide it for less cost if you value your time at minimum wage.

You don’t need to hack things, the providers are required to cooperate. I just wonder if anyone has tried to actually do it.

Re: Turning a TV set-top box into a Linux computer (2022)

#106

Post by pjmlp »

bigape911 wrote: post #84
vctrnk wrote: post #75

Earlier quoted context omitted.

I won't hold my breath. From the article: > In theory, we might be asked to give this device back. In practice, these devices are written off as soon as they’re sent to customers. In my country, there are various ISPs with the same OEM boxes from SDMCtech. They went to the trouble of asking manufacturer to put a custom SDIO encryption chip onboard. If someone dares to touch the firmware and/or included apps (not syst…

Then when it's time to get rid of it, throw it back at their door step since it doesn't belong to you

Actually many of those providers in some jurisdisions require returning the device at contract termination.

Re: Turning a TV set-top box into a Linux computer (2022)

#107

Post by wolrah »

anonuser123456 wrote: post #57
NKosmatos wrote: post #49

Vendors of STBs should unlock them so that we don't get so much e-waste. These boxes are most of the times locked, whereas they could be repurposed for many interesting uses (linux machines, android boxes, educational devices...), now they will be thrown away, remain in closets/garages or at the best be recycled. Tried to unlock my Vodafone TV box (Sagemcom DIW387 if I'm not mistaken), but with no luck since there is…

We aren’t going to modify our security protocols so a handful of people can mod their STB, sorry :P

> We aren’t going to modify our security protocols so a handful of people can mod their STB, sorry :P

Don't try to pass off lockdown nonsense as "security". If your "security" depends on a locked down end user device it's a broken design from the start.

I'd be willing to bet that the restrictions actually enforce the execution of insecure components, almost every locked down device ends up that way because the chain of vendors involved in approving updates doesn't really care about anything that doesn't affect their profit margins.

Just admit it's all about the margins, don't lie about security.

Re: Turning a TV set-top box into a Linux computer (2022)

#108

Post by kjs3 »

redfast00 wrote: post #25
cassepipe wrote: post #24

Almost all my friends in France have a old ISP modem router that their former ISP did not bother getting their hands back onto when they changed providers. I would love to repurpose them. Where do I start with ?

Try to identify a serial port on the PCB, connect a serial adaptor to it (careful to get the pins and voltage right!) and take it from there (Edit: or google the PCB board markings, maybe somebody already did this)

Finding the JTAG port is also useful, combined with something like OpenOCD.

Re: Turning a TV set-top box into a Linux computer (2022)

#109

Post by hungryforcodes »

tenebrisalietum wrote: post #13
xwdv wrote: post #7

I struggle to think of what purpose a device that wasn’t meant to be a Linux computer would realistically serve beyond nefarious goals.

This is an ethically neutral activity. The mere act of transforming a device into such a computer doesn't add or remove any nefarious goals, if you have those goals, you can get another device intended to be a Linux computer and still accomplish them (and it would be much easier). If the transformation is done in contravention of the owner, it's bad, but it sounds like from the article that the ISP has written it off…

In a worst case scenario the company (so called "owner), will just charge you for its replacement. Since it was well calculated that

a) the box was useless and

b) would never be asked for again and

c) (as I've said) would just be charged a certain amount for non-return...

I hardly see how it's an ethical activity. If the owner was one person that was needing this device -- fine. But this is just a company doing business...

Re: Turning a TV set-top box into a Linux computer (2022)

#110

Post by squarefoot »

detrites wrote: post #93
squarefoot wrote: post #65

Very interesting writeup, bookmarked! I wish there was a community willing to reverse engineer those very cheap DVR/NVR video surveillance boxes and boards sold on Ebay and Aliexpress. They have USB, SATA, some GPIOs and quite fast ADC chips on board to achieve high definition video sampling so they could be repurposed for various uses like SDR. They already run Linux inside, although it is predictably tight closed,…

Do you happen to know other spec's on these or similar? (Eg, CPU type/speed, RAM etc)

Not much info unfortunately. Some of them apparently use a HiSilicon (owned by Huawei) chipset; the following Alibaba page lists some of them among others.

https://www.alibaba.com/countrysearch/CN/dvr-motherboard.htm...

Here are a few pages I found that could turn out interesting:

https://securitycamcenter.com/firmware-chinese-dvr-nvr-secur...

https://github.com/hisilicon

And as widely reported, they're quite vulnerable.

https://github.com/tothi/pwn-hisilicon-dvr

https://www.exploit-db.com/exploits/44004

I wonder if those vulnerabilities could be used to gain root access to the hardware in order to either patch it and make decent security devices, or repurpose them completely, as the hardware is interesting and dirt cheap.

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