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File Systems for Electronic Surveillance Devices?

Posted by Cliff on from the discrete-audio-data-storage dept.

An anonymous reader asks: "A friend recently discovered that her vehicle had been bugged by the police (for reasons I won't go into here). It seems the set-up had been wired into the car's electronics, so that whenever the car was going the microphones were recording the occupants' conversations. Unfortunately I didn't get to see everything she recovered, as she was a bit exuberant in her removal and disposal. However, I have been given a 20G Fujitsu notebook hard drive and some kind of audio processing chip from a manufacturer by the name of Topoint, and have been asked if I can examine the contents. You can read on to hear about my efforts so far, but I have several questions: If the surveillance device came from a vendor, what kind of file system might they use, and if - as I suspect - it is encrypted, do I have any options other than writing zeros over the drive and putting it to less controversial use?" "Not knowing what to do with the audio chip, I focused on the notebook hard drive. I got an adapter, connected it as master on my desktop and booted up. After checking the BIOS to see if the drive was recognised (it was), I was presented with a full-screen simple line diagram showing the floppy drive slot, a floppy with an arrow in front of it and across the bottom, the F keys with the F1 key depressed. Hitting F1 with or without entering a disk resulted in 'Non-system disk error...' So much for the direct approach.

Next I set the drive as slave and booted Linux (Mandrake and then a few Live CDs), but the drive contents weren't recognised due to the lack of a partition table. So, I kept it as slave and ran a few forensic and data recovery tools in Windows: DFSee and tools from Mare Software and Runtime Software. I couldn't recognize the file system or recover anything from the drive with these, so I figure it isn't formatted with any of the standard FAT, FAT32, HPFS, NTFS, JFS, EXT2/3 or REISER file systems. I've kind of reached the limit of my abilities here, but my curiosity has been stoked.

Does anyone have any suggestions or comments - useful or otherwise? To anticipate a few in advance: Yes, listening devices might well run Linux. We're not in the US and are more interested in human rights than terrorism. My friend obviously knows most of what has been recorded, but wants to figure out how long the bug was in place."

6 of 136 comments (clear)

  1. Interesting...could it be that there isn't a FS? by mc_barron · · Score: 5, Interesting
    What an interesting story! Could it be possible that the drive has no structure? Couldn't the audio data be directly written from the beginning to the end of the disk sectors without being an actual file?

    I would try grabbing the data off of the drive as an image, then "playing" the image as if it were one large audio file.

  2. A better idea by crstophr · · Score: 5, Funny

    Forget reading the data.

    Format the whole thing with fat32
    Fill the entire drive with gay porn.

    Reinstall in car.

    1. Re:A better idea by dgatwood · · Score: 5, Funny
      Even better, find a bunch of people on the street who you don't know. Hand them scripts and ask them to read them while you drive the car. In those scripts, they should confess to dozens of crimes that never happened. One might admit that he/she hid the body in the foundation of the Microsoft building, another that he murdered some famous person (who isn't dead... or better yet, who is, but who died naturally, ideally before the 'murderer' was born), etc.

      As the recording gets longer, make the conversations get more and more outrageous. One person tells the other that he used to be a she who, in turn, used to be a he. Another goes into a tirade about how his father beat him, so now he feels like he should beat his children... except that he doesn't have children, so he beats up random children on the playground instead. At some point, the line "I'm not your Uncle, I'm your father" appears. "But wait, that would make me your brother." "Eww.... You married your sister?"

      By the end, everybody is sleeping with everyone, family trees are intertwined in amusing ways, the priest is having an affair with the school nurse, and the horny schoolgirl talks about how she once had sex with the governor/president/whatever. It all culminates with someone deciding to off him/herself, not because he/she did anything wrong, but because he just found out that his sister had become a prostitute to raise money to help pay for his cancer treatment while he sold his cancer drugs to help pay for her AIDS treatment. Be sure to accurately simulate the sound of a gunshot through the roof of a car.

      Watch the amusement as the police A. try to find the blood stains, B. try to find the bullet hole, C. try to figure out who the heck all those people are, and D. arrest a senior government official for underage sex. If you pull it off without getting caught, it would be the prank of the century....

      --

      Check out my sci-fi/humor trilogy at PatriotsBooks.

  3. Investigate the audio chip first by DavidYaw · · Score: 5, Insightful

    Assuming the audio chip has a part number on it, try to get the datasheet from the manufacturer. See what format data it outputs, and perhaps the data on the hard drive is raw output from the audio chip. (If the audio chip's native format is 12 bit, 8k samples/sec, then that might be what's on the HD. If the audio chip supports some sort of audio compression, etc...)

    A reasonable first step would be to try to take the entire contents of the drive and send it out your sound card... (dd /dev/hdb /dev/audio or something like that (I'm not a Linux guy)). If the HD was used just to dump raw wave data to, you'll hear something (possibly squeaky voices if it's the wrong format, but you'll be able to tell there's something there). Even if there's a filesystem of some sort that you can't interpret, that would just be noise at the beginning of the playback, before it got to the real audio.

    If it really is encrypted, then you'd have to do some sort of cryptanalysis, and I have no idea how to even begin cryptanalysis on audio data. At that point, I say open the HD up and scrape the platters until they're shiny silver instead of shiny brown.

  4. Things to try by Requiem+Aristos · · Score: 5, Interesting

    First, if you encounter something like this in the future, don't try to boot from it. (It's always possible there could be code to detect an unauthorized machine and start deleting itself.)

    Next, as another poster suggested, use dd to get a copy of the disk. Make a few copies while you're at it, and write them to DVDs, DLTs, or some other media.

    Finally, do the processing. Here are some ideas:
    Write all zeros to the drive, then put it back in the car. Drive around for set intervals of time (100 minutes, 200 minutes, etc.) then pull the data from the drive to see how much was filled up. (Hint: it's from the start of the drive to where the long string of zeros starts.) Try it with minimal noise, try it with talking, and try it with music.

    Run 'file' or 'strings' on the image. Try catting it to your sound device. Plot the data in both 2D and 3D and look for any patterns. (Encrypted data shouldn't have any.)

  5. Re:Hmm by ar32h · · Score: 5, Informative

    Toppoint may build custom chips / build clone chips.
    Any/all numbers on the chip would probably be more useful than the manufacturer's name.

    Also, and perhaps a red herring, could the device in question be the product found here?
    It is a GPS tracker with audio recording capability. It also happens to take 20G drives and uses a SOIC for control.
    It may be a jump, but Toppoint could have been the board builder.