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Cellphones Handhelds Power Security

Jailbroken Devices Compromised By Charging Stations 93

Posted by Soulskill
from the charged-with-computer-fraud dept.
mask.of.sanity writes "Data can be stolen from Windows, Android and Apple devices by unassuming power charging towers. In an attack demonstrated at the Defcon hacking conference, mobile phone charging units were rigged to pull data from phones plugged into them. Researchers found many jailbroken and modified devices activated USB functions when they were plugged in, or simply rebooted."
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Jailbroken Devices Compromised By Charging Stations

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  • by Anonymous Coward

    Nitpicking here... An iPhone that is jailbroken has its security compromised where anything is possible via the USB connection. However, an Android device that has root still has its security mechanisms 100% intact unless someone automatically checks "yes" everytime the su dialog pops up, or has a really craptastic ROM.

    Yes, some ROMs might allow for a root prompt to allow a hacked charger to slurp data via ADB, but this can be easily disabled by just turning debug mode off.

    • by pruss (246395) on Saturday August 20, 2011 @04:31PM (#37156222) Homepage

      1. Moreover, there is quite a bit you can do with adb even without root: the adb shell normally gets privileges that are higher than those ordinary non-system Android apps get, though lower than full root privileges. (E.g., you can silently install and deinstall arbitrary apps from an adb shell.) So keeping debug on and plugging into untrusted devices is probably not such a great idea, whether the device is rooted or not. Moreover, if debug is on, then even if the device isn't rooted, an attacker can often just silently install an app that roots the device via whatever vulnerability roots a given device, and then get full root privileges.

      2. The Superuser app that I use can be set so that it remembers su permissions after the first time one is asked and doesn't ask again if the same app requests the permission (technically, it will ask again if the app requests the permission in connection with another su command, but most root-using apps just request permission for an su shell, and then do their work in the shell). I keep that setting active, since I do things that require root so often (my SuperDim app to dim the display below what the OS normally allows for use at night; on boot setting the exec permission on my SD card so I can move app libraries to it; adjusting CPU governor settings; using my Force2SD app to move recalcitrant apps to SD; running a script to do a tar backup of all of /data; etc.). It would be a real nuisance to be constantly prompted. But there is an obvious security cost to the convenience. I am willing to accept that cost, especially since I currently use only two root-based apps that I didn't write myself, and I think they are trustworthy apps. So only two apps that I didn't write have the silent su authorization enabled.

      • by mjwx (966435)

        So keeping debug on and plugging into untrusted devices is probably not such a great idea

        Keeping Debug on is not a good idea.

        Plugging it into an unknown or untrusted device is an even worse one.

        An Android user who keeps debug on probably knows enough to not plug it into strange charging devices.

    • by blair1q (305137)

      Yes, but see how they worded the threat?

      If you have done something to totally drop security on your magic data port, then something you connect to that port that you do not understand can pwn your gifs.

      Pretty simple really.

      Same deal with flying. You're okay until someone lets the snakes loose.

    • by zoloto (586738)
      Your comparison of Android and iOS are Oranges and Apples. (:P) Just because someone's jailbroken their iOS device doesn't mean it's insecure from that point, and often times that security hole is the purveyor of other actual fixes to prevent unauthorized access. Including the one it (the jb method) used to jailbreak the device. ie: the PDF exploits used for jailbreaking iOS devices.
  • Hmm (Score:5, Insightful)

    by LocalH (28506) on Saturday August 20, 2011 @04:04PM (#37156024) Homepage

    So basically, you connect an untrusted device to a device you trust somewhat, and you're shocked when bad things can happen?

    It's like people who would pick up a random USB drive off the ground and then plug it into their computer without taking precautions. Why is this any different?

    • Re:Hmm (Score:5, Insightful)

      by Anonymous Coward on Saturday August 20, 2011 @04:48PM (#37156330)

      I'm not sure if your USB drive example is a good comparison to this situation. Charging stations are being commonplace and showing up in airports, coffee shops, etc. Businesses that people trust.

      I think think this is more like a fake ATM machine. People are so used to ATMs being everywhere, that little thought is given when they enter their PIN number into one. It's not something that the average person is going to think twice about.

    • by Joce640k (829181)

      Simple solution: Get a USB extension cable which only has power connections, not data.

    • by erroneus (253617)

      In technical terms, you are correct. But the belief was that this was a power station, not something intended to compromise. True that it caught people unaware. It would have caught me unaware. It goes to show that using complex connectors for power isn't such a great idea since it requires trust which people are unaware they are giving.

      This has given me cause to pause. I just checked my phone. It's default setting on reboot is for USB connections to prompt on the phone what to allow. USB debugging i

      • by Dwedit (232252)

        It's just about like trusting that a power outlet will deliver the voltage and frequency it claims to, and not something else that will blow up your device.

        • The analogy only works in part. In your case, your maximum possible loss is the device itself and any data not properly backed up. In the case explained in the article, the exploit means that your data ends in untrusted hands.

          Of course, it depends a lot of the nature of the data that you have in your phone. For my phone, it would be a greatest setback breaking the device than making public any data held in it. But maybe some other people has in their smartphones the numbering of their secret banks accounts

  • The phones are charged through the usb port and usb ports transfer data. Wow someone realized they could put more than two wires in the charger cable.
    I made my mp3 player play through an old tape deck yesterday I must be a genius.
    • Re:Duh (Score:5, Informative)

      by Miamicanes (730264) on Saturday August 20, 2011 @04:56PM (#37156382)

      What you need is a USB CondomCable with the D+ and D- pins shorted together. No data can flow, and if the bad guys didn't bother to try and implement proper power protocol, you'll get the added satisfaction of frying THEIR hardware when your phone cranks up the juice and tries to suck down 1.7A instead of politely sipping 100mA. Just don't ever use such a cable by mistake to connect your phone to a pc or laptop belonging to yourself or a friend.

      • by artor3 (1344997)

        If the D+ and D- lines are shorted in the cable itself, then it will draw as much current as the host can source, all the time. Your phone has no control over whether that number is 100 mA or 1.7 A. Furthermore, shorting the D+ and D- lines together is highly unlikely to damage the host. It's not like hackers are fabbing their own substandard chips. If you really want to make a cable that will kill the host, without being as obvious as sticking a USB connector on to the other end of a 120 VAC cord, you

        • Re:Duh (Score:4, Informative)

          by Kookus (653170) on Saturday August 20, 2011 @05:44PM (#37156694) Journal

          I don't think he meant that the d+/- lines were what fries the host, he was indicating that the phone wouldn't think it's connected to a computer and it would draw higher amps because it thinks it's hooked up to just a charger. So if the host didn't limit amps and it's wires weren't rated for 1.7A, then it would result in them overheating and hopefully damaging something.
          The whole purpose was to make a connector that actually works, not something to destroy the host. The ancillary prize was damaging hosts if they were advertised as just a charger and they really weren't.

          • by ColaMan (37550)

            The USB spec limits negotiated current to a max of 500mA (I think).

            Any sort of active device will have some sort of hub inline and it should simply shut that port off if it goes into overcurrent.

            • by Timmmm (636430)

              Yeah but in practice, chargers don't limit their current to 500 mA. See: http://www.ladyada.net/make/mintyboost/icharge.html [ladyada.net]

            • China has an official government standard for micro-USB charging that basically says, "if the data lines are shorted together, the client can legitimately assume that the host is a charger capable of supplying 1.7 Amperes". By virtue of everything coming from China, that basically means that there's now a worldwide standard for the same. However, most cheap USB chargers DON'T short the pins together, because then they'd have to have a regulator with proper heatsink capable of supplying up to 1.7A continuous

        • by tlhIngan (30335)

          If the D+ and D- lines are shorted in the cable itself, then it will draw as much current as the host can source, all the time. Your phone has no control over whether that number is 100 mA or 1.7 A.

          The danger is though that the power supply is well-protected. Most cheap USB power adapters may only be able to provide 500mA. Sure, if you try to draw 1A, they can try to supply it (provided the voltage rails don't dip too low), until something burns up. Usually the regulator as at 500mA it can survive with what

      • Really, you'd just need to put enough series inductance on the D- and D+ lines to foul up any data transfer. That way systems like the iPhone's charge sensing resistor trick would still work.

  • consider what happens when you plug an ipod classic into an usb slot.

    or if you got adb enabled on android. or if your android is from a manufacturer which has rather fancy control sw suites on pc. the usb is generally considered a trusted port or indeed more like plugging to a host.

    "or simply rebooted" implies that they rebooted when they were attached to usb, which sounds a bit far fetched tbh.. the charging units could host a malicious pc on a chip, sure.

    you could fight this by getting an extension cable

    • by mpoulton (689851)

      "or simply rebooted" implies that they rebooted when they were attached to usb, which sounds a bit far fetched tbh.

      Many phones will boot when connected to power if they are off to begin with. I think that's what he meant.

  • Simply create some couplers in which you provide an MF couple, but drop data lines (2 and 3). 1 and 4 would be passed through.
  • by mpoulton (689851) on Saturday August 20, 2011 @04:20PM (#37156160)
    I flew on Air Canada a few weeks ago and they had USB ports for charging integrated into the seatback touchscreen displays. When I plugged my phone (HTC Incredible running CM7 nightlies) into it with a USB data cable, it indicated a valid data connection to a host controller! I was surprised and thought the seatback device probably contained a small PC to handle the interactive display. I tried to poke around on the host device to see what I could find, but didn't get anywhere with it. For some reason it didn't even occur to me that the "poking around" could be going the other way. If someone could compromise those seatback devices, the phone contents of thousands of passengers could be automatically collected...
    • I haven't flown on Air Canada but I imagine that the system on V Australia planes is quite similar. There the USB port can be used for charging, but you can also connect a remote storage device (probably intended for a thumb drive, but a phone in USB storage mode would work the same) in order to playback photos, mp3s and videos (divx I guess) through the seat-back entertainment system.

    • by Osgeld (1900440)

      there should be no reason those plugs have all 4 pins installed, thats just asking for it

      • by Anonymous Coward on Saturday August 20, 2011 @05:10PM (#37156468)

        AC Chargers that can supply up to 1000ma short the two data pins together to tell the phone it can draw that high amount of current.
        USB devices connected to a controller are only allowed to draw 500ma, and only after negotiation with the host.
        A USB connected to a port where the data pins are not shorted AND cannot negotiate a higher current with the host is only allowed to draw 100ma.

        So removing the data pins from a USB port will prolong charge duration 5x or 10x

    • I was surprised and thought the seatback device probably contained a small PC to handle the interactive display.

      If it linked to the flight control systems you would have been really surprised...but not for long.

    • by drinkypoo (153816)

      This would be a major danger with IEEE1394 because it's a route to memory via DMA and only recent platforms have an IOMMU worth its sand. But with USB it's only a danger if your device is very trusting... Of course, a lot of small devices will search for a filename based on their device type in order to perform a flash upgrade...

    • by cshake (736412)
      Since iDevices (at least the iPods I've used) have the ability to charge from the "dumb" wall bricks with a USB port, why not bring a custom cable with you to unsecured locations that only connects to VCC and Gnd on the USB port, and has the appropriate resistor between the data lines to indicate a valid charging station? Voila, no risk of data going either way and you still get a charge from an unknown location.
      • you know.. the iphones come with this nifty adapter that plugs into an even more common receptacle. usually two slots and a hole in the wall with no data connection whatsoever. I hear that it's 120VAC. Just sayin......
    • There could be a simpler reason for this... many devices charge MUCH faster if they sense a valid data connection... without the data connection, you're limited to normal USB line level. It's possible that the only thing on the other side is some caps and a resistor.

    • I tried to poke around on the host device to see what I could find, but didn't get anywhere with it

      If you drill down to something called TCAS or FMS I advise you to leave it alone.

    • by Anonymous Coward

      The ports were originally intended for game controllers to be attached to the entertainment system.

    • Most likely reason for this might be that, there might be a loose connection and the phone detected the connection as a data connection instead of pure power connection rather than anything sneaky happening. This is done b shorting out the D+, D- pins through a ~200Ohm resistor which indicates to the phone that it can draw more than 500mA from the source (500mA is the maximum current a standard USB port can provide on a computer). Reference: A good source: http://www.maxim-ic.com/app-notes/index.mvp/id [maxim-ic.com]
  • It's hard to beat DroidWall and su status to keep "all open apps" from "constantly connecting for reasons unclear."
  • In an ideal world, the software wouldn't be so damn trusting; but this seems like a problem that(until the ideal world appears on the back of the world-peace pony) could be solved by a ~$1 cheapass dongle device.

    Connector suitable to phone/device in question on one side, whatever tricks are needed to convince that class of device that this is an Officially Blessed Charger(usually some resister-based fuckery on the data pins or a simple USB handshake of some sort) and USB cable with only +5 and GND lines
  • Told you so (Score:4, Informative)

    by Animats (122034) on Saturday August 20, 2011 @06:31PM (#37156932) Homepage

    Told you so on February 6, 2009. [slashdot.org]

    Back in 2009, it was just a Windows autorun problem. Since then, Google and Apple have been able to screw up in the same way.

    Coming soon, I suppose, attacks on appliances via "smart meter" data links. Not everything should have a data link.

  • They were capable of pulling data, but took the ethical route instead, displaying a warning message informing attendees of the dangers of using public charging kiosks.

    I think this should be made more clear in /. article.

    • by Anonymous Coward

      Even worse, there was a sign on the actual station that said something like "never plug your phone into an untrusted jack" and yet people were there all weekend plugging their phones into the thing. It's DEFCON, folks, c'mon.

  • They thought making it's users unable to turn off USB debugging was a positive feature they should all enjoy. Screw that. I'm also a little annoyed Android doesn't support SD encryption, taking the S out of SD.

    • I'm also a little annoyed Android doesn't support SD encryption

      I think Android 3.x does. You can also buy WhisperCore for earlier devices (not that I'd trust encryption I can't compile myself). I think there was a port of LUKS to Android 2 as well. But only the newest mobil eCPU's (e.g. in the Droid 3) have hardware AES, so it's going to eat battery on older stuff (and most Android phone already have terrible battery life).

      When I can get 3 days charge and encryption on an Android phone I'm buying one, fu

  • it makes and receives calls, it sends and receives texts, has a calendar and alarm clock and it makes it very much so i don't waste more time on facebook when i'm not at home, i kinda like it, jailbreak that
  • Will turning them *off* first help prevent this from happening?

    • by coolmadsi (823103)

      Will turning them *off* first help prevent this from happening?

      Someone elsewhere in this topic commented that that is what they thought was meant by "rebooted" - i.e. when plugged into a charger, the phone turned itself on if it was off. I don't know if that is the case here, but I have seen an old phone of mine do something similar when it was off and I plugged it in to charge.

  • Does anyone make a cable and/or a tiny Male2Female adapter that passes through only the power pins? With one of those on our keychains we could safely charge our iDevices anywhere without fear of data diddling.

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