4 ms·

Could you elaborate on that?

by dchest 12y ago

joshu 12y ago
because how the passwords are stored affects whether they are recoverable. are you dense?
- mkal_tsr 12y ago
  He asked a simple question, what's with the hostility of asking if he's "dense" ?
  - joshu 12y ago
    It's not hostile. It's like he cannot fathom why someone might want to know the thing that they are asking.
    - dchest 12y ago
      Well, I'd like to know what scheme they used too, however this is only because of curiosity and my interest in this topic. Some people seem to need (or even demand by law) to know the scheme, because they see it as a way to assess their security, however they fail to provide a satisfying answer on why exactly they need this knowledge (even when they are told to change passwords!), and how this will change their assessment. I probably need to structure my questions like 5 Whys (https://en.wikipedia.org/wiki/5_Whys https://en.wikipedia.org/wiki/5_Whys), providing the first few answers myself: Q. We need to know the exact password hashing/encryption/storage scheme eBay used. 1. Why? - We need to know if the passwords are easily recoverable. 2. Why? - We need to assess our risks. 3. Why? - ...
- dchest 12y ago
  That's not an actionable information. There is no reason not to change password and not use different passwords for different websites even if they use yescrypt* with 2 TB ROM. *) https://password-hashing.net/candidates.html https://password-hashing.net/candidates.html
  - joshu 12y ago
    If they were someone who used the same password everywhere, then if the password was recoverable, they need to change the password everywhere. Not the brightest password strategy but a valid question.
    - dchest 12y ago
      They still need to change the password everywhere they used it even if eBay used a state-of-the-art password hashing. (Remember that eBay asked users to change passwords?) But even so, the knowledge of password storage scheme in this case is actually harmful! Suppose Alice is reusing passwords, like you said. She learns that eBay used bcrypt, and due to this knowledge thinks her password is safe, and doesn't change her password anywhere apart from eBay. Good? Nope.
      - hackinthebochs 12y ago
        >They still need to change the password everywhere they used it even if eBay used a state-of-the-art password hashing I don't see why you keep saying this. These sorts of one-size-fits-all responses to security is why the state of security to day is so bad. A salted hash in itself is useless if you can't decrypt it. If their hashing technique was properly implemented then a good password will be impossible to decrypt. In this scenario there is no reason to change your password. Personally, the value of an easy to remember password is higher than the miniscule risk of it being decrypted and used for nefarious purposes (which is limited by the fact that nothing of importance is linked to this particular password). I probably won't be changing my ebay password.
        dchest 12y ago
        No, good password is infeasible to brute-force (not "decrypt", hashing doesn't encrypt anything; I invite you to research the topic you're talking about) even if you use non-salted SHA-1. Slow password hashing is there to protect weak passwords. In the event compromise like this, you need to change password regardless, because you can't be certain if, for example, attackers had access to server memory (remember that password is kept there before hashing?) or not. These sorts of one-size-fits-all responses to security is why the state of security to day is so bad. This sentence is completely false.
tombrossman 12y ago
I think the reason people like to know this detail is so they can gauge how urgently they need to act and change their password(s). If the attackers got plaintext data (worst-case) and users re-used logins on other sites, it's a 'holy shit drop everything and change passwords now' moment. If Ebay followed best practices then affected users know they can wait a day or two and update passwords at a convenient time. Hashing, salting, encrypting all buy you time to react. Your other comment is correct though, once a password database is compromised all those affected must assume it will be cracked and so they must change passwords. The only variable is how quickly they should act.
- dchest 12y ago
  Passwords leaked 3 months ago, it's "holy shit drop everything and change passwords now" moment in any case.
- MasterScrat 12y ago
  If used properly, can't the good hashing techniques be "safe", at least if the salt is not leaked?
  - dchest 12y ago
    Good hashing techniques store "salt" along with password. Salt is not a secret key, it's a public value used to make password hashes unique. Good hashing techniques increase costs for attackers to brute-force passwords. If they securely encrypted passwords or password hashes, and the key was not leaked, then passwords are safe. However, the probability of attackers stealing the database of passwords and not stealing the encryption key for it is pretty low. Knowing anything of this still doesn't affect user actions, who should change eBay passwords and never reuse them for anything else.
  - mnw21cam 12y ago
    You're thinking of pepper, not salt. Salt is a random value that is added to a password before it is hashed, so that two identical passwords do not hash to the same value. The value is different for each hashed password, and is stored alongside the hash. Pepper is a configured value that is the same for all hashed passwords, and is added to the password (and salt) before it is hashed. It is kept secret, and effectively turns the hash function into a secret hash function. Its merit can be argued because if an attacker is able to compromise your hashed password database, they could possibly have compromised your configuration and discovered the pepper too. However, it does add an extra hurdle for an attacker.
perlgeek 12y ago
Many breaches in the past revealed that passwords were somehow "hashed" or "encrypted" in ways that made it much easier than necessary for the attacker to obtain the clear text passwords. For example if passwords are only hashed with md5, with no salt, that's basically worthless; md5 is simply too easy to brute force. Same for sha1 (not quite as easy to reverse, but rainbow tables help). So the mere fact that the passwords were somehow "secured" doesn't mean much by itself.
- dchest 12y ago
  I know that different password storage schemes provide different security. I don't see how knowing what particular scheme they used would affect your actions.
  - sgk284 12y ago
    If you use a secure password and the scheme the company uses is something like scrypt or bcrypt with high work factors, you can be near-certain that your password won't be cracked by an attacker. The amount of computation is just extraordinary. That said, you would still probably want to change your password if you're paranoid.
    - dchest 12y ago
      If you are capable of estimating the cost of cracking your password, you're capable of understanding that you should use different passwords on different websites and that you should change your password in event of compromise. In which case, the fact that attackers know your leaked password doesn't change anything. The same thing applies to knowing the particular password hash they used: if your password had enough entropy, attackers won't be able to break it even if eBay used "unsalted" SHA-1. But this doesn't change anything, because see previous paragraph. If, say, your grandfather used the same password for Hotmail and eBay, and he tells you that his password was "bestjetpilot"[1], and asks for your advice on what to do, will you tell him to change both passwords, or just the eBay one? What if he used "y62BYmHoCsjScov6QSOgGCL"? What would you tell him? How would your advice change if you knew the particular password storage scheme eBay used? Do you now need to know which scheme Hotmail uses, because the password is reused on both websites? [1] http://pages.ebay.com.au/help/account/create-password.html http://pages.ebay.com.au/help/account/create-password.html

Could you elaborate on that?

by dchest 12y ago

Could you elaborate on that?

joshu 12y ago

because how the passwords are stored affects whether they are recoverable. are you dense?

mkal_tsr 12y ago
He asked a simple question, what's with the hostility of asking if he's "dense" ?
- joshu 12y ago
  It's not hostile. It's like he cannot fathom why someone might want to know the thing that they are asking.
  - dchest 12y ago
    Well, I'd like to know what scheme they used too, however this is only because of curiosity and my interest in this topic. Some people seem to need (or even demand by law) to know the scheme, because they see it as a way to assess their security, however they fail to provide a satisfying answer on why exactly they need this knowledge (even when they are told to change passwords!), and how this will change their assessment. I probably need to structure my questions like 5 Whys (https://en.wikipedia.org/wiki/5_Whys https://en.wikipedia.org/wiki/5_Whys), providing the first few answers myself: Q. We need to know the exact password hashing/encryption/storage scheme eBay used. 1. Why? - We need to know if the passwords are easily recoverable. 2. Why? - We need to assess our risks. 3. Why? - ...
dchest 12y ago
That's not an actionable information. There is no reason not to change password and not use different passwords for different websites even if they use yescrypt* with 2 TB ROM. *) https://password-hashing.net/candidates.html https://password-hashing.net/candidates.html
- joshu 12y ago
  If they were someone who used the same password everywhere, then if the password was recoverable, they need to change the password everywhere. Not the brightest password strategy but a valid question.
  - dchest 12y ago
    They still need to change the password everywhere they used it even if eBay used a state-of-the-art password hashing. (Remember that eBay asked users to change passwords?) But even so, the knowledge of password storage scheme in this case is actually harmful! Suppose Alice is reusing passwords, like you said. She learns that eBay used bcrypt, and due to this knowledge thinks her password is safe, and doesn't change her password anywhere apart from eBay. Good? Nope.
    - hackinthebochs 12y ago
      >They still need to change the password everywhere they used it even if eBay used a state-of-the-art password hashing I don't see why you keep saying this. These sorts of one-size-fits-all responses to security is why the state of security to day is so bad. A salted hash in itself is useless if you can't decrypt it. If their hashing technique was properly implemented then a good password will be impossible to decrypt. In this scenario there is no reason to change your password. Personally, the value of an easy to remember password is higher than the miniscule risk of it being decrypted and used for nefarious purposes (which is limited by the fact that nothing of importance is linked to this particular password). I probably won't be changing my ebay password.
      - dchest 12y ago
        No, good password is infeasible to brute-force (not "decrypt", hashing doesn't encrypt anything; I invite you to research the topic you're talking about) even if you use non-salted SHA-1. Slow password hashing is there to protect weak passwords. In the event compromise like this, you need to change password regardless, because you can't be certain if, for example, attackers had access to server memory (remember that password is kept there before hashing?) or not. These sorts of one-size-fits-all responses to security is why the state of security to day is so bad. This sentence is completely false.

tombrossman 12y ago

I think the reason people like to know this detail is so they can gauge how urgently they need to act and change their password(s). If the attackers got plaintext data (worst-case) and users re-used logins on other sites, it's a 'holy shit drop everything and change passwords now' moment. If Ebay followed best practices then affected users know they can wait a day or two and update passwords at a convenient time. Hashing, salting, encrypting all buy you time to react. Your other comment is correct though, once a password database is compromised all those affected must assume it will be cracked and so they must change passwords. The only variable is how quickly they should act.

dchest 12y ago
Passwords leaked 3 months ago, it's "holy shit drop everything and change passwords now" moment in any case.
MasterScrat 12y ago
If used properly, can't the good hashing techniques be "safe", at least if the salt is not leaked?
- dchest 12y ago
  Good hashing techniques store "salt" along with password. Salt is not a secret key, it's a public value used to make password hashes unique. Good hashing techniques increase costs for attackers to brute-force passwords. If they securely encrypted passwords or password hashes, and the key was not leaked, then passwords are safe. However, the probability of attackers stealing the database of passwords and not stealing the encryption key for it is pretty low. Knowing anything of this still doesn't affect user actions, who should change eBay passwords and never reuse them for anything else.
- mnw21cam 12y ago
  You're thinking of pepper, not salt. Salt is a random value that is added to a password before it is hashed, so that two identical passwords do not hash to the same value. The value is different for each hashed password, and is stored alongside the hash. Pepper is a configured value that is the same for all hashed passwords, and is added to the password (and salt) before it is hashed. It is kept secret, and effectively turns the hash function into a secret hash function. Its merit can be argued because if an attacker is able to compromise your hashed password database, they could possibly have compromised your configuration and discovered the pepper too. However, it does add an extra hurdle for an attacker.

perlgeek 12y ago

Many breaches in the past revealed that passwords were somehow "hashed" or "encrypted" in ways that made it much easier than necessary for the attacker to obtain the clear text passwords. For example if passwords are only hashed with md5, with no salt, that's basically worthless; md5 is simply too easy to brute force. Same for sha1 (not quite as easy to reverse, but rainbow tables help). So the mere fact that the passwords were somehow "secured" doesn't mean much by itself.

dchest 12y ago
I know that different password storage schemes provide different security. I don't see how knowing what particular scheme they used would affect your actions.
- sgk284 12y ago
  If you use a secure password and the scheme the company uses is something like scrypt or bcrypt with high work factors, you can be near-certain that your password won't be cracked by an attacker. The amount of computation is just extraordinary. That said, you would still probably want to change your password if you're paranoid.
  - dchest 12y ago
    If you are capable of estimating the cost of cracking your password, you're capable of understanding that you should use different passwords on different websites and that you should change your password in event of compromise. In which case, the fact that attackers know your leaked password doesn't change anything. The same thing applies to knowing the particular password hash they used: if your password had enough entropy, attackers won't be able to break it even if eBay used "unsalted" SHA-1. But this doesn't change anything, because see previous paragraph. If, say, your grandfather used the same password for Hotmail and eBay, and he tells you that his password was "bestjetpilot"[1], and asks for your advice on what to do, will you tell him to change both passwords, or just the eBay one? What if he used "y62BYmHoCsjScov6QSOgGCL"? What would you tell him? How would your advice change if you knew the particular password storage scheme eBay used? Do you now need to know which scheme Hotmail uses, because the password is reused on both websites? [1] http://pages.ebay.com.au/help/account/create-password.html http://pages.ebay.com.au/help/account/create-password.html