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> If you care about this, then put the laptop in a tamper-evident bag. How does this procedure work for multiday evil maid situations? The first day while you'

by zx2c4 8y ago

> If you care about this, then put the laptop in a tamper-evident bag. How does this procedure work for multiday evil maid situations? The first day while you're out the maid replaces your collection of plastic disposable tamper-evident bags with faulty ones that open with a particular chemical but otherwise look identical. The second day the maid tampers with your laptop and you don't notice. Do you just have to take the whole box of additional bags with you everyday? That seems prohibitively inconvenient.

tripletao 8y ago
If this were a job interview, then I'd say "put the spare bags in with the laptop"... Or the "bag" can be the laptop's existing case. You can put seals (stickers, or the sparkly nail polish trick mentioned below) over all the fasteners and seams of the laptop, fill all the non-power ports with epoxy, etc. None of these make tampering impossible, but they can make it uneconomic. I don't think anyone at serious risk of these kinds of attacks lets computers out of their physical control. I've seen agencies that do the seals/epoxy even for computers inside their secure facilities, presumably to give their guards more time to catch an inside tamperer.
gh02t 8y ago
So part of the point of tamper evident seals is that they are difficult to duplicate. The bags themselves should be readily verifiable, eg with a serial number for basic verification at least. The sort of seals used for nuclear treaty enforcement actually most commonly use little fibers that are randomly mixed in with plastic and their pattern is photographed, making them extremely difficult to duplicate.
jdietrich 8y ago
Professional poker players have been dealing with this type of risk for years. Major poker tournaments present a juicy target for organised hacking gangs. A high-stakes pro might have tens or hundreds of thousands of dollars deposited in their PokerStars account. Hundreds of professional players in a tournament cardroom means hundreds of very valuable laptops left in hotel rooms. The most sensible precautions seem to be a) full-disk encryption with a strong passphrase, b) hardware 2fa using a token that is stored separately from the computer, c) physically securing the machine whenever possible and d) tamper-evident seals covering screwholes or seams. If your adversary is capable of beating these precautions, you're probably screwed anyway. https://www.f-secure.com/weblog/archives/00002647.html https://www.f-secure.com/weblog/archives/00002647.html

by zx2c4 8y ago

tripletao 8y ago

If this were a job interview, then I'd say "put the spare bags in with the laptop"... Or the "bag" can be the laptop's existing case. You can put seals (stickers, or the sparkly nail polish trick mentioned below) over all the fasteners and seams of the laptop, fill all the non-power ports with epoxy, etc. None of these make tampering impossible, but they can make it uneconomic. I don't think anyone at serious risk of these kinds of attacks lets computers out of their physical control. I've seen agencies that do the seals/epoxy even for computers inside their secure facilities, presumably to give their guards more time to catch an inside tamperer.

gh02t 8y ago

So part of the point of tamper evident seals is that they are difficult to duplicate. The bags themselves should be readily verifiable, eg with a serial number for basic verification at least. The sort of seals used for nuclear treaty enforcement actually most commonly use little fibers that are randomly mixed in with plastic and their pattern is photographed, making them extremely difficult to duplicate.

jdietrich 8y ago

Professional poker players have been dealing with this type of risk for years. Major poker tournaments present a juicy target for organised hacking gangs. A high-stakes pro might have tens or hundreds of thousands of dollars deposited in their PokerStars account. Hundreds of professional players in a tournament cardroom means hundreds of very valuable laptops left in hotel rooms. The most sensible precautions seem to be a) full-disk encryption with a strong passphrase, b) hardware 2fa using a token that is stored separately from the computer, c) physically securing the machine whenever possible and d) tamper-evident seals covering screwholes or seams. If your adversary is capable of beating these precautions, you're probably screwed anyway. https://www.f-secure.com/weblog/archives/00002647.html https://www.f-secure.com/weblog/archives/00002647.html