Wallet Hack on 4/25

[zebedee]

I now believe I know how they got my friend's coins.


She'd given her account a short, 4-letter alias.  Her 10-letter password began with that alias, in a way that a human might be able to guess the first 8 letters(the final two were numbers).  Doh.
 
I believe that several attack vectors are being used, and that one is someone is cycling through short aliases, perhaps regardless of spelling, and longer aliases that are dictionary words. Knowing the alias used to be enough, without 2 factor, for blockchain.info to give up your encrypted wallet. They are then brute forcing passwords, trying both common passwords, dictionary words, and others beginning or ending with the alias.

[marcus_of_augustus]

Guess there are a lot of GPU clusters coming available now that are basically set up for brute forcing passwords .... "strong" password does not mean what it used to?

[jubalix]

Guess there are a lot of GPU clusters coming available now that are basically set up for brute forcing passwords .... "strong" password does not mean what it used to?

thats why you need 20 plus long password

[silvereagle]

Update - after speaking some more with my affected customer I am no longer convinced his password was indeed strong enough.

Maybe passwords were brute-forced after all? silvereagle - just how strong was your password?

Will be happy to hear about any progress in figuring this out.

Alias was very short so may have been hackable.  Password was 15 characters long but made up of multiple words that may have been found in dictionary.  Possible but permutations to put that many words together would still be extremely high.

[zebedee]

Also I have setup several wallets with deliberately weak passwords that are unemptied.

Do any of those wallets have easily guessable aliases?  I imagine if they had, they would be empty now.  Of course, now you're forcing email confirmation for aliases (sometimes, always?) so it wouldn't work so easily.

[Dabs]

Here is an example of my logins for banks and Mt. Gox:

Username: kl2uggsyf3yue9g4e2
Password: t#nocq2*l4c*b1yibxf%tazzh0^$)^ft0

Both are limited by what the system will accept. Some of my bank usernames only accept letters and numbers (alphanumeric). Some corporate bank accounts also include a bank generated company code (which I don't have control of).

The above is not an actual account, it is just an example.

For forums, like this one, I use a simple username, like, Dabs. The password is just as long and complicated.

Where my username is not likely to ever be seen by anyone else, I pick a long random username. Banks and bitcoin exchanges and bitcoin wallets are examples.

[jubalix]

Here is an example of my logins for banks and Mt. Gox:

Username: kl2uggsyf3yue9g4e2
Password: t#nocq2*l4c*b1yibxf%tazzh0^$)^ft0

Both are limited by what the system will accept. Some of my bank usernames only accept letters and numbers (alphanumeric). Some corporate bank accounts also include a bank generated company code (which I don't have control of).

The above is not an actual account, it is just an example.

For forums, like this one, I use a simple username, like, Dabs. The password is just as long and complicated.

Where my username is not likely to ever be seen by anyone else, I pick a long random username. Banks and bitcoin exchanges and bitcoin wallets are examples.

I would like to see sites use KEY files like true crypt does (but check client side never upload)....a JPG as a KEY file is basically unhackable, even keyloggers would be hard as they would have to record where you pointed your mouse

[Dabs]

Keyfiles stored on your computer would have to be uploaded to their servers for hashing, OR your client side browser will have to perform the hashing offline, and submit your result online.

In either case, MITM or eavesdroppers can intercept the keyfiles. There would have to be some sort of public key or SSL encryption going on for this to work, so no one else can grab your keyfile or the hash of that keyfile.

If your computer is compromised, they can get your keyfile.

[jubalix]

Keyfiles stored on your computer would have to be uploaded to their servers for hashing, OR your client side browser will have to perform the hashing offline, and submit your result online.

In either case, MITM or eavesdroppers can intercept the keyfiles. There would have to be some sort of public key or SSL encryption going on for this to work, so no one else can grab your keyfile or the hash of that keyfile.

If your computer is compromised, they can get your keyfile.

but how would they know which out of 1x10e6 files is my key file, or which combination of 2, 3 or more key files is are my key files?

how do they even know i use a key file???

[Meni Rosenfeld]

Here is an example of my logins for banks and Mt. Gox:

Username: kl2uggsyf3yue9g4e2
Password: t#nocq2*l4c*b1yibxf%tazzh0^$)^ft0

Were you a victim of this? Are you providing evidence that this was not brute-force, or simply explaining how to properly choose passwords?

[willphase]

Just a friendly PSA that if you ever had a weak password or a weak alias on your blockchain.info account, then someone could be running bruteforce on your wallet as we speak, regardless of whether you later upgraded the security (e.g. added 2FA or added an IP block, or deleted/changed your alias)

So, if you upgrade your security, I recommend you move your bitcoins off the keys that might have been previously compromised.  It's not like changing your password on blockchain.info changes your keys.

If in doubt, generate a new blockchain.info wallet, set up 2FA and secure passwords, IP blocks etc etc, then move your bitcoins from your old potentially compromised wallet to your new one.  I personally would consider any keys stored under an 'insecure blockchain.info wallet' compromised (but not perhaps until some time in the future).

Will

[Remember remember the 5th of November]

Also having a feature to block other IPs from entering the account would be nice, with the ability to add exceptions(home,work,phone).

[Amph]

best user and password is= empty wallet

[Kaiji]

For storing large numbers of bitcoins an online bitcoin bank is needed. Unfortunately it will only be a matter of time before it is hacked or the owner of the site absconds with users bitcoins.

[Dabs]

but how would they know which out of 1x10e6 files is my key file, or which combination of 2, 3 or more key files is are my key files?

how do they even know i use a key file???

The keylogger trojan or malware is surely going to be capturing your screen. They can know which file is your keyfile. I'm not saying that this is being done now, I am saying this is possible.

Were you a victim of this? Are you providing evidence that this was not brute-force, or simply explaining how to properly choose passwords?

I don't use block chain, so I am not a victim, merely showing how to properly choose good passwords.

[jubalix]

but how would they know which out of 1x10e6 files is my key file, or which combination of 2, 3 or more key files is are my key files?

how do they even know i use a key file???

The keylogger trojan or malware is surely going to be capturing your screen. They can know which file is your keyfile. I'm not saying that this is being done now, I am saying this is possible.

Were you a victim of this? Are you providing evidence that this was not brute-force, or simply explaining how to properly choose passwords?

I don't use block chain, so I am not a victim, merely showing how to properly choose good passwords.

no key loggers don't usually do screen captures....you would soon notice this as your hard-rive would be full or your bandwidth consumed or always slow....

[Aseras]

it would probably help if blockchain's iphone and android app didnt store the main password in plaintext.

[shawshankinmate37927]

Also having a feature to block other IPs from entering the account would be nice, with the ability to add exceptions(home,work,phone).

Blockchain.info's My Wallet service already offers this ability.  It can be found under the Security menu option on the Account Settings page.  (Of course, this won't help if a hacker already has copies of your private keys.)

[Newar]

it would probably help if blockchain's iphone and android app didnt store the main password in plaintext.

There's an update available for Android that fixes this. https://bitcointalk.org/index.php?topic=40264.msg1966450#msg1966450

[Luckybit]

I posted same thing couple topics down.

Second time in two weeks.  One coin each time. Changed pw on every account and activated logging.

No log of withdraw.

Now getting freaked little.

Create a new account from a Linux liveCD and consider your computer compromised. Use someone elses computer. Set up two factor authentication. Perhaps consider investing in a Yubikey.