Slashdot Mirror
The Keyboard That Could Phone Home
An anonymous reader writes "University of Pennsylvania researchers have developed a keylogger they call the JitterBug that can modulate passwords or other information into normal traffic by adding imperceptible delays to keypresses as people use keyboard and network-intensive apps like telnet and remote desktop. The idea is that the delays in keypresses cause delays in packets, and data can be encoded in those delays. There's no software or extra network activity that the victim can see, but anyone who can see the traffic (even if it's encrypted) could grab the data. Here's the scary part: the researchers say that it could be manufactured into a keyboard, making these keyloggers widespread and virtually undetectable."
Well, probably. But what you're doing is just adding noise to the system - this can be circumvented by just taking longer to send the time-based data (ie send the data with greater redundancy, so that it's more noise tolerant). Also, adding jitter would slow the network connection because you can't make transmission faster, you can only slow it by the mean delay of your introduced noise.
A more effective method would be to use a method of transmission that wasn't time-dependent on what the user typed. For example, ssh could be designed so that it sent a packet every 100ms (whatever - I don't know the specific time) regardless of what the user had typed. I think this would render this attack useless, but would still introduce some latency...
The article says 'In applications such as telnet and remote desktop, a packet is sent every time a user presses a key' - is this the case with ssh too? I mean - surely *nobody* uses telnet for secure communications!
yeah, laptops could implement this in the keyboard controller. Or even the USB hub could do it.
you have to trust the pc vendors, as they have nothing to gain, and everything to lose, in lawsuits and lost sales. But what if their government comes along and says 'add this back door'. They'd comply.
Case in point: Lotus notes put a back door in export versions of notes:
http://catless.ncl.ac.uk/Risks/19.52.html#subj1
they sent messages with 64 bit encryption (!), but 24 bits of the key was hidden in the message, where the NSA knew to look, or otherwise given to them. You only had 40 bit keys, which upset the swedish government.
Moral: You cant trust closed source apps any more than closed source hardware.
Just enable (as it's usually disabled for things like SSH) Nagle's algorhitm, and it should destroy most of the timing information.
For those who don't know, it's a TCP optimization that buffers data until there's a packet worth of data, or an ACK is received for the last packet sent, so that writing 1 byte of data into a socket doesn't immediately result in sending a packet with 40 bytes of overhead, and 1 byte of data.
Incorrect. It's true that there'd be no way to prevent the keyboard from collecting data, but one could certainly prevent the successful transmission of the collected data. The way the data would be encoded would be via the timing of the packets sent in response to keystrokes; that logic path most definitely involves software levels, specifically (in the example given of a remote terminal session) the choice of the software to send a packet once per keystroke. The proposed solution of introducing jitter to the packets is indeed a solution, and a simple straightforward one at that.
- First they ignore you, then they laugh at you, then ???, then profit.