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QoTW #41: Why do we lock our computers?

2012-11-30 by . 2 comments

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Iszi chose this week’s question of the week, Tom Marthenal‘s “Why do we lock our computers?” - as Tom puts it:

It’s common knowledge that if somebody has physical access to your machine they can do whatever they want with it, so what is the point?

This one attracted a lot of views, as it is a simple question of interest to everyone.

Both Bruce Ediger and Polynomial answered with the core reason – it removes the risk from the casual attacker while costing the user next to nothing! This is an essential factor in cost/usability tradeoffs for security. From Bruce:

The value of locking is somewhat larger than the price of locking it. Sort of like how in good neighborhoods, you don’t need to lock your front door. In most neighborhoods, you do lock your front door, but anyone with a hammer, a large rock or a brick could get in through the windows.

and from Polynomial:

An attacker with a short window of opportunity (e.g. whilst you’re out getting coffee) must be prevented at minimum cost to you as a user, in such a way that makes it non-trivial to bypass under tight time constraints.

Kaz pointed out another essential point, traceability:

If you don’t lock, it is easy for someone to poke around inside your session in such a way that you will not notice it when you return to your machine.

And zzzzBov added this in a comment:

…few bystanders would question someone walking up to a house and entering through the front door. The assumption is that the person entering it has a reason to. If a bystander watches someone break into a window, they’re much more likely to call the authorities. This is analogous with sitting down at a computer that’s unlocked, vs physically hacking into the system after crawling under a desk.

It removes a large percentage of possible attacks – those from your co-workers wanting to mess with your stuff – thanks enedene.

So – protect yourself from co-workers, casual snooping and pilfering and other mischief by simply locking your machine every time you leave your desk!

Liked this question of the week? Interested in reading it or adding an answer? See the question in full. Have questions of a security nature of your own? Security expert and want to help others? Come and join us at security.stackexchange.com.

2 Comments

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  • Billy ONeal says:

    Of course — if the machine in question us using a whole disk encryption system then locking might be even more secure. The assumptions that physical access == root usually depend on being able to do an end run around the host OS. Sure, data can be destroyed; but the contents of the machine aren’t in someone else’s hands.

  • very sweet blog and it content about Why do we lock our computers? very useful information also so it is the right combination of information and printing keep doing that in future also.

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