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Of Encrypted Hard Drives and "Evil Maids"
Schneier has a blog piece about Joanna Rutkowska's "evil maid" attack, demonstrated earlier this month against TrueCrypt. "The same kind of attack should work against any whole-disk encryption, including PGP Disk and BitLocker. ... [A] likely scenario is that you leave your encrypted computer in your hotel room when you go out to dinner, and the maid sneaks in and installs the hacked bootloader. ... [P]eople who encrypt their hard drives, or partitions on their hard drives, have to realize that the encryption gives them less protection than they probably believe. It protects against someone confiscating or stealing their computer and then trying to get at the data. It does not protect against an attacker who has access to your computer over a period of time during which you use it, too."
physical access > digital security
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I'm imagining a bunch of geeks dressed up in maid outfits.
Seriously, if you're worried about some hacker assassin breaking into your house or office and installing a bootloader, you're either doing something REALLY secretive (in which case the computer probably shouldn't even be on a network to upload any data back in the first place) or you're the kind of person who thinks Obama has your name on an "important persons" list and is coming for your guns. If someone has physical access to your machine and has the skills to install a bootloader, you're pretty much boned anyway, encryption or not (encryption isn't going to stop a simple keylogger). That's nothing new. Fortunately, for the vast vast majority of us, there are very few hacker black operatives who are running around breaking into hotel rooms just so they can get a single Visa number from Bob the dipshit middle manager. Newsflash Bob, YOU'RE NOT THAT IMPORTANT!
Oh, and I love how the article calls the prospect of a ninja hacker hotel maid sneaking a bootloader onto your laptop and then sneaking back into your room later to retrieve the data a "likely scenario." What hotels is this guy staying at anyway?
SJW: Someone who has run out of real oppression, and has to fake it.
If you are the kind of person that are in the danger zone of this happening (not that you would leave a computer with such sensitive information in your hotel room.); You would probably feel a lot better if you were able to checksum the bootloader when returning, maybe from an external usb drive. This would offcourse run it's own OS, not being done from the bootloader(for obvious reasons).
Doolittle :
Bomb no.20 : To explode of course.
You could have found the evil bartender.
You leave your laptop at the hotel and you go out to take a beer. There, you meet the evil bartender, who because of a common past becomes your friend and starts inviting you to more and more beer. Then he closes the bar and you both go to a strip club where you meet the evil bartender's girlfriend and her friend who we shall call "Foxette".
The next morning, you wake up in an unknown appartment with Foxette and a guy you don't even know. You quickly get out of there and go to work, with such a massive headache than when asked about the laptop's full disk encription, you answer is "the what?".
I didn't read the RTFA, but aren't MSFT's BitLocker supposes to validate the boot path (from BIOS code to bootloader up to the BitLocker decrypter) with the help of the TPM chip?
Evil maids are easy to spot because of their goatees.
Mother, do you think they'll like this sig?
Someday I want to invent an attack, but only because I want the privilege of naming it.
And some day I'd like to be hit by the attack you invent, because saying that I've been hit by an "all-knowing frog" attack would simply be cool.
Cheers,
Ian
You can see why it's called the "evil maid" attack; a likely scenario is that you leave your encrypted computer in your hotel room when you go out to dinner, and the maid sneaks in and installs the hacked bootloader. The same maid could even sneak back the next night and erase any traces of her actions.
Maybe if she's an idiot. Once you've installed your own bootloader, it can neatly remove itself. (After installing malware, or transferring the encryption keys and data it needs over the network.) Why in the world would the maid unnecessarily repeat the riskiest part of the entire attack?
But more to the point, it must be a slow week. Why are "serious" security researchers even wasting time on something this obvious? Of course your software-based hard disk encryption is hosed in the event that an attacker gets hold of your machine and can alter the bootloader. Hell, the really sophisticated bad guys aren't even going to do anything this difficult or risky. After all, the encryption key has to be in RAM somewhere whenever you're using software-based encryption (hardware encryption excluded). A well-engineered piece of malware will recover it, and two-factor authentication isn't going to help you.
Even trusted boot will only get you so far against a motivated adversary with this much sophistication. Don't leave your vital computing equipment behind in your hotel room.
The hypnotoad security tool protects against the all-knowing frog attack, but comes with its own drawbac--ALL GLORY TO THE HYPNOTOOL.
Workaround 1) Make sure only women have the information.
Workaround 2) Preventative castration
Workaround 3) Shoot anyone with pliers who comes within 10 feet
Workaround 4) Duress code which releases false information. (this one's likely practical but only as a delaying tactic; it's going to hurt a lot when the interrogator finds the information doesn't verify)