from the stay-safe-and-secure dept.
We all know that when somebody gets unauthorised access to your computer hardware that security is out of the window! But what if you have to leave your hardware unattended but ostensibly in a 'secure' location - your hotel room or somebody else's home? fab23 has submitted this article on what you can do if that is the case:
The so-called evil maid attack is an attack against hardware devices utilizing hard- and/or software. It is carried out when the hardware is left unattended, e.g., in a hotel room when you're out for breakfast. The attacker manipulates the device in a malicious way, e.g.:
There are several ways to minimize the risk of an unnoticed, successful evil maid attack. Which road you go depends on your personal threat model (and your budget, of course).
[...] If you want to have a cheap solution to be reasonably sure nobody messes unnoticed with your device when you have to leave it alone, you may carry out some countermeasures, e.g.:
Seal all screws with nail polish or glue with glitter pieces in it, and take pictures that are stored offline so that you will be able to spot manipulations
Seal not needed peripheral interfaces (e.g. USB ports)
Lock needed peripheral ports with tamper-proof solutions (e.g. one-time locks which have to be destroyed to access the port)
Leave the device in the bootup password prompt of the FDE (Full Disk Encryption) password:
Reboot your device to the FDE password prompt
and enter the first few chars of the correct password (important!)
make sure the device stays in this mode till you return (e.g. has enough power or the power supply is plugged in, disable energy saving settings, ...)
When you're back, enter the rest of the FDE password, and if the device boots, then you could be reasonably sure it hasn't been tampered with. Of course, you have to examine the device physically thoroughly, e.g., the screws, peripheral ports, seals, etc. One important precondition for this to work is that the FDE boot code allows the password prompt to stay as it is after entering some chars. Fedora 7 and Ubuntu 20.04 seem to work, but Bitlocker (Windows) does not. Is this bulletproof? No. Will this be reasonably secure? Depends on your threat model. But it's definitely better than doing nothing, having the OS left up and running, or having the device powered off completely. Stay safe and secure!
So, if you absolutely have no other option, what do you do to ensure that your data remains as secure as possible?