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241

Obscurity isn't a bad security measure to have in place. Relying upon obscurity, as your sole or most substantial security measure, is more or less a cardinal sin. Kerckhoff's Principle is perhaps the most oft-cited argument against implementing security through obscurity. However, if the system is already properly secure according to that principle, this ...


206

That all depends on the system, the attacker, and the level of preparation they had. If they have unlimited preparation, they could do effectively anything that they could do with an unlimited access window. Even if they do not have in-depth knowledge of the specific system, it would not be difficult to very quickly inject malicious code that allows for ...


193

I would recommend setting it to 0000 or some other specified combination (doesn't really matter what). "Mashing around the dials" is a little vague, but I would guess based on my own behavior that people would tend to move most or all of the dials at once, which would create a strong correlation between the current combination and the lock combination. For ...


164

I think the assumption here is wrong. They don't have physical access to the machine. They have supervised access to a very limited control panel for a machine which is built into a bomb-proof safe, bolted to the ground and hooked up to an alarm system with an armed response force. Get the machine out of the vault and away from supervision and then yes... ...


136

ATM are supposed to be tamper resistant, and to actively react upon any detected breach of physical security, notably by marking bills with some highly conspicuous and hard to remove ink, and also by committing honourable seppuku. For that matter, an ATM should be compared with HSM, payment terminals and smart card. You can imagine the ATM as a kind of Davy ...


134

This is not a problem that has a social solution. No amount of corporate policy will save you. Humans are social animals. In the end, if people can let other people in, they will. Even if you may be very security aware and not let anyone in, 95% of your collegues will act differently. You have to work with human nature, not against it. So if you want to ...


121

The simple answer is: nothing. This has already been done for many years, with keys being cast or created from blanks using hand drawn copies, photographs, remembered shapes etc all being successfully used, both by locksmiths and criminals. A 3D printed key will do just as well, if strong enough, or it could be used to cast a key if necessary, or as ...


121

That's what the envelope is (or should be) for: In order to use your password, one needs to break the seal of the envelope you signed. When you think your password was abused, you can ask to see the envelope with your signature and check if it is still unopened. All you need to do is that should your management ever require your password, change the ...


119

In some places they have a saying: "opportunity makes the thief". All you're doing by screen-locking a computer is making the cost of hacking it just a little bit harder. Security is an economic good, with a price and a value. 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 ...


117

In theory zeroing or any predetermined sequence is more secure as you could, in theory make a guess at how far someone might move the dials. In practice this is probably a bit far fetched and anything with a combination lock probably has larger concerns eg the combination being known by too many people or the fact that any number between 1950 and 2018 ...


116

RAM is used to store sensitive non-persistent information in a lot of cases. Encryption keys would be a common example. Sometimes it is possible to remove RAM and place it into another device to dump the contents - often with the aid of liquid nitrogen. For more information, see the Wikipedia article for Cold Boot Attack.


111

... how secure is a QR-code? Data in a QR code are kind of protected against accidental damage by having some error correction but they are not protected against deliberate manipulation. Also, an attacker might completely replace the QR code in the document with a different one.


103

Keeping the design secret does not make the door insecure per se; however, believing that it adds to security is a dangerous delusion. If revealing the details of the authentication system would allow breaking it, then that system is pure junk and should be discarded. Therefore, if you did your job properly, then revealing the details should be harmless. If ...


90

In 2011 the news was reporting on HP Printers catching fire. HP Responded saying that there was a hardware element called a "thermal breaker" to prevent this from happening. The researcher never produced a burning pile of printer. Also in 2011 Charlie Miller was researching the firmware on Apple's batteries trying to get them to explode or catch fire. ...


87

As the guys previously said, nothing! Even more, I've been working on such a project myself at the university! (albeit I don't say this as an official target, of course) I am trying to do duplicate a key from a single photo, with some assumptions to make it a realistic problem such as having a coin of a known size next to it for size calibration and ...


81

I don't think that you interpret the rule you've heard in the right way. If an attacker has physical access to an encrypted but switched off device he cannot simply break the encryption provided that the encryption was done properly. This is true for an iPhone as much as it is for an fully encrypted notebook or an encrypted Android phone. The situation is ...


79

My advice would be to remove the secrets from the drop-box and store them elsewhere. Your instructions have to be easily human readable by anyone, but they can include instructions on how to get access to the properly secured part of the data. That lets you separate the accessibility side of things from the security side. Once you can think about security ...


74

Get a USB device. Put all secrets on the USB, preferably in a KeePass file. In the documentation, tell the new person where the USB is and how to unlock it, but put the device in a secure physical location like the owner's office, the company safe, a secure deposit box, etc. Somewhere out of the reach of the public, and away from the prying eyes of other ...


73

Could I mitigate that risk by taking a regular usb cable and cutting the data (but not the power) cables? Or does the usb protocol needs a data handshake to begin charging? Such a cable does exist, so a data handshake must not be required. Such cords are discussed on some Stack Exchange sites: Micro USB cables that only charge but no data, no mounting etc ...


72

Physical access, in many, likely most, situations means a total loss of security - for a variety of reasons (this all assumes encrypted disks): Theft - An attacker could steal the server or disks, to attack at their pace. This allows an attacker to take their time, and you have no idea if they've actually gained access to data. Physical Modification - If I ...


63

You seem to have a pretty clear understanding of the risks. As others have stated it highly encouraged to use a strong password, so if you are running a sensitive service, then by all means, please use strong passwords only. When using a weak password, there are a couple risks that come to mind which you did not mention: There may be other services besides ...


61

Raid 5 stripes the data across the disks but the blocks used for striping are typically pretty big. At the very least they will bewhole sectors but normally they will much larger than that. For example madm defaults to half-megabyte chunks. Even one sector is big enough that you are likely to find recongisable chunks of text and with typical chunk sizes it ...


61

You protect yourself by politely challenging people who are trying to get in without using the controls. You simply ask to see their pass or offer to escort them to reception/security. I use the simple phrase, "I'm sorry, I do not know who you are so I cannot just let you in. May I escort you to reception?" If they resist, I monitor them and quietly inform ...


60

All other answers are fine. I'm going to offer you a classic security perspective. Starting a fire/flood is a textbook scenario for physical penetration/exfiltration. People under stress are less likely to challenge strangers. A fire can be used to destroy forensic evidence, in particular when there's insider involvement. An earthquake or, indeed, any ...


58

QR codes are normally not protected against manipulation. But: You could include a digital signature in the data so anyone can check if the QR code is made by you and has not been modified. Then the only thing an attacker can do is replace the QR code by an other QR code you made. Such an approach wil typically work like this: On a secure server, a key ...


57

Consider getting a software product which fully encrypts your hard drives. Such a software will prompt the user to enter the password used to encrypt the hard drive during boot. Without the correct password, the hard drive (including both the OS and any data) can not be decrypted, the system won't boot and the user won't get any access to the data. In that ...


54

It's a risk management thing, really. 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. Hitting WinKey+L or clicking the lock button is next-to-zero cost for you as a user. Taking the time ...


54

The answer to your question is yes, though whether this will ever actually help them is dependent on the lock and their 'skill'. With a typical (cylinder?) deadbolt repeated attempts can advance an impressioning attack with a key blank (see tylerl's answer for more detail), if using picking tools the extra visits will improve the feel for the lock and in ...


52

Yes, there's a classic attack that involves incremental access. The attacker starts out with a blank key that fits into the lock in question. The attacker approaches the door, puts the key in, jiggles the key a bit, grumbles something about how the office numbers changing, and leaves. Then in private he examines the impression pattern on the key. Where ...


51

In some cases yes, you can guess the most frequently used keys by the wear marks. That's how I know that apparently I use the L, M, N, A and E keys a lot - the keys are now just black, the letter is faded. And one special key being significantly more used than the others - unless it's "{", "}" or ";" and you happen to be a programmer - could allow to ...


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