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Hacking Transcend WiFi SD Cards

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Re: Hacking Transcend WiFi SD Cards

#21

Post by mikeash »

jrockway wrote: post #6
q3k wrote: post #2

My experience with embedded systems allows me to be fairly certain that this bugfest is due to an electronics engineer writing the software for the card. Way too often small R&D teams, especially working on new products, have EE people being assigned to part-time-embedded-programmer roles. This is especially scary as some of these teams work on internet-facing pieces of hardware - home routers/gateways, etc. One cool…

As someone who's written software for all his life, I'll posit that most "software engineers" write code like this. People don't test corner cases; they just shit out code, check that it works in the browser, and ship it. That's why the regexes like /.PNG/ are in there: they work, but they don't prevent the security problems they intend to prevent. If the engineer writing the code had written unit tests that checked…

I don't think it's that they assume they don't make mistakes, but simply that they literally can't do any better. For some programmers, making something work at all is a mighty struggle, and once it does work, that's the best the can do.

We were all there once. It's a stage you hit when learning to program. Some of us passed through it, while others simply remain there forever.

Re: Hacking Transcend WiFi SD Cards

#22

Post by kabdib »

voltagex_ wrote: post #10
q3k wrote: post #2

My experience with embedded systems allows me to be fairly certain that this bugfest is due to an electronics engineer writing the software for the card. Way too often small R&D teams, especially working on new products, have EE people being assigned to part-time-embedded-programmer roles. This is especially scary as some of these teams work on internet-facing pieces of hardware - home routers/gateways, etc. One cool…

I can attest to the low quality of router firmware, go grab the source from Billion or Netgear and have a look. Homework question: What's running on your blu-ray player?

Java. Oh, don't worry, that's like totally secure.

[tries to keep straight face, fails utterly]

Re: Hacking Transcend WiFi SD Cards

#23

Post by tacoman »

jtchang wrote: post #3

This is awesome. A few years back I originally wrote an open source EyeFi server in Python ( http://returnbooleantrue.blogspot.com/2009/04/eye-fi-standal... ). I could not actually hack into the card though and get root which is what I really wnated. These memory cards are super fun and I've been meaning to pick another up to give it another go.

Awesome. I've been using your software since mid 2009. I've transfered ~100GB of pictures using it. Thanks!

Re: Hacking Transcend WiFi SD Cards

#25

Post by toble »

femto wrote: post #18
jrockway wrote: post #6

Earlier quoted context omitted.

As someone who's written software for all his life, I'll posit that most "software engineers" write code like this. People don't test corner cases; they just shit out code, check that it works in the browser, and ship it. That's why the regexes like /.PNG/ are in there: they work, but they don't prevent the security problems they intend to prevent. If the engineer writing the code had written unit tests that checked…

Another explanation is that there is no benefit to the manufacturer in writing tighter code. Tighter code means more time spent on testing and review, but probably wouldn't increase sales. From a bottom line point of view, the mantra is get it working and ship it.

Yep. Whenever you work in an industry that involves churning out software as quickly as possible, it's easy to appreciate that commercial pressures are often too great to test properly. Whereas with start-ups (for example), they're usually well funded and have a strong focus on building great software.

Re: Hacking Transcend WiFi SD Cards

#26

Post by voltagex_ »

kabdib wrote: post #22
voltagex_ wrote: post #10

Earlier quoted context omitted.

I can attest to the low quality of router firmware, go grab the source from Billion or Netgear and have a look. Homework question: What's running on your blu-ray player?

Java. Oh, don't worry, that's like totally secure. [tries to keep straight face, fails utterly]

I really should start blogging - one of my many unfinished projects is a teardown and reverse engineering effort of a Philips BD player. Java isn't even the half of it.

Re: Hacking Transcend WiFi SD Cards

#27

Post by caf »

robinson-wall wrote: post #15

Contrived, sure, but you could use these exploits to upload all files added to the card somewhere, assuming it can find a wireless network to connect to. Maybe even just keep a hidden copy on the part of the FS invisible to the host system if there is enough free space. "Oh sure I've got an SD card you can borrow..."

You could do a lot of neat things - like make an SD card that automatically GPG-encrypts every file that gets stored on it.

Re: Hacking Transcend WiFi SD Cards

#29

Post by martey »

> After navigating the filesystem and downloading scripts, it is obvious, and not surprising, that this system is using busybox...

Does anyone know whether Transcend provides source code [0] upon request? The EULA in the user manual for the product [1] mentions that it might contain "GPL Components", but I could not find any additional details.

[0]: http://www.busybox.net/license.html

[1]: http://www.transcend-info.com/files/Manual/WiFiSD_Manual_v1....

Re: Hacking Transcend WiFi SD Cards

#30

Post by krasin »

voltagex_ wrote: post #26
kabdib wrote: post #22

Earlier quoted context omitted.

Java. Oh, don't worry, that's like totally secure. [tries to keep straight face, fails utterly]

I really should start blogging - one of my many unfinished projects is a teardown and reverse engineering effort of a Philips BD player. Java isn't even the half of it.

Please, do so. It would be interesting to read.
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