Comment by msla
3 hours ago
The bank has the best doors, the best locks, and the best cameras, and it is patrolled by a guard who props the doors open to so he doesn't have to keep fooling with the locks and points the cameras the other way to extend his smoke break. SeL4 would be another system used by humans.
It's always possible to break a perfect system by moving an additional layer of abstraction outward, and attacking one of the assumptions upon which it's built. Some of our era's highest security systems - game consoles - have been broken by undervolting them until the logic failed.
> It's always possible
It's often possible. But not all systems are vulnerable to undervoltage attacks. For example, I don't think the iphone secure enclave is vulnerable to this.
And good security uses "defence in depth". Multiple layers which each individually need to be compromised to break the whole thing. To hack chrome, you need a vulnerability in the renderer or VM. Then you also need a sandbox escape, and a way to use that to attack the browser's parent process. This is much harder to do.
I'd stick with always. Defense vs offense in anything reasonably complex suffers from one issue that simply cannot be overcome. To defend, you need to defend against every single possible imaginable attack, from now until forever. To attack, you need to find a single attack that works. And on a practical level all systems need to be accessible by somebody, yet that somebody is himself also now a part of your security structure and is never going to be 100% reliable, both in terms of corruption and incompetence.
> not all systems are vulnerable to undervoltage attacks. For example, I don't think the iphone secure enclave is vulnerable to this.
Then there's decapping / depotting, a world of different types of microscopy - some destructive some not, directed EM attacks, etc.
> And good security uses "defence in depth"
And automation has enabled "offense in depth"
> To hack chrome, you need a vulnerability in the renderer or VM. Then you also need a sandbox escape, and a way to use that to attack the browser's parent process.
Or you just phish the user into installing your exploit. There's always another layer. Always a potential exploit. Because ultimately the same properties of the universe which permit computation within a closed system allow for predictably observing and influencing it. The expense and hassle of doing so are widely variable, of course.
I once worked on AUD 450M banking project, the root password was kept in a kickstart file and unchanged, root SSH was allowed. The bank didn't care until I told the external security auditor who included it as part of their report.
Snitch
I hope you get cancer.
There's absolutely no way to account for humans, who can be tricked, or pressured, or just make human sized mistakes.
Again, of course there is.
Decades ago, I worked in a bank in an old building. The door had a card reader for access. You boop your card and the door opened. People would hold the door open for each other all the time out of politeness, even when they didn't know each other. Security told us not to do that, but it's hard to convince people to stop being polite.
I had a laptop stolen from my desk in a place like that once. (Not a bank - but similar door-card reader system). This guy came in in the middle of the day, wearing overalls. He confidently walked through the door after someone, like he belonged there. He walked up to my desk, swiped my laptop and just strolled out.
At the bank, they've replaced the door with mechanical gates and a security guard. The gates - physically - only let one person to walk through at a time. You can't hold a gate open any more. And the security guards stop anyone who tries.
Is it 100% foolproof? No. But it's way more secure. It would have stopped that laptop thief.
There's this pernicious, defeatist attitude that if you can't make a system 100% secure, so you shouldn't try. That's misguided. Most systems can be made orders of magnitude more secure than they are today. It just takes a bit of care and work.
Then there's no such thing as security.
By the way, there are countless ways to account for humans. There are entire branches of engineering devoted to this. If you don't want someone to leave the bank with a pen customers use for signing checks, you just chain it to the desk. If you don't want the installer to forget to put the pen-chain in, make a photo of the chain part of the checklist required to get paid. If you want to... etc.
The idea is that you determine an acceptable level of risk, then secure to that level. Maybe the acceptable level of risk chosen by companies is wrong. Maybe we need to increase that risk exposure via heavier fines and regulations. Maybe the cost of reducing that risk is too high already. Maybe we need to fund that. Maybe it's too confusing and we need to research better standard practices. I dunno. But this is not some unsolvable problem.