164

My question isn't about the mathematical strength of passwords which obviously will depend on the lyric that is chosen and how one goes about passwordifying it, it is more about the the predictability of the total amount of possible passwords that are likely to pop up using this method. This is a good question, and I'm going to depart from the norm here, ...


160

No, you cannot determine how close you guessed looking at the hash. A hash function is designed with this in mind: one single changed bit on the input must change a lot of bits on the output. Its called Avalanche Effect. Bellow are SHA1 hashes for some of your example passwords: cbfdac6008f9cab4083784cbd1874f76618d2a97 - password123 ...


123

One of the most logical explanations is that those accounts were associated with a bot. Same goes for password like 18atcskd2w. Graham Cluley wrote an article about this: So, Just Why Is 18atcskd2w Such a Popular Password? Can so many people really be choosing to protect their online accounts with the same, seemingly random choice of “18atcskd2w”, “...


118

If I'm understanding your question properly, the attack you are proposing is to brute-force passwords against a server like this, then once it shows you the MFA screen, go try that password on other websites that this user has accounts on. This is a great question! Good find! But you seem to be overlooking two points: This is no weaker than not having MFA, ...


105

Another possibility : Sojdlg123aljg is latin characters translation from another alphabet. For instance, a common password "ji32k7au4a83" is from mandarin "我的密碼", meaning "my password" (source). Using this online keyboard, you can validate that typing successively j-i-3 maps to 我. However it does not works for Soj... So either it is a different language, ...


100

This would probably be explained in the auditory lecture that these slides accompany. My guess is that he's calculating this assuming that users generally enter their correct passwords. You only need to cycle through options for r until you find one that produces a correct hash. If you've been given the correct password, then you will come across an r that ...


95

The password hashes for MS Office 97-2003 are vulnerable to collision attacks. That is, multiple passwords exist that should be able to open the document. That also means that the password "iemuzqau" is not necessarily the original password that was set by the author. It is just one of the passwords that should be accepted, because it matches the internal ...


90

It's horrible :) To provide some numbers to back claims by other answers: This provides some numbers of how many songs are popular per year. For the last decade it was as low as 300-400 Top40 hits per year! Average word count for a song is 300-600, depending on the style, and they do 7-10 words per sentence (And I imagine that's the comfortable length of a ...


85

Full disclosure: I work for a company, which distributes such cards. This answer however is my own personal opinion of them. The idea of these cards is that some users are just really bad at remembering passwords or pass phrases. The naïve approach would be to tell users "Just get better at remembering passwords", but experience has shown that such advice ...


83

I URL decoded it, then decoded it from base64, then passed it to an online hash database. The result was: Hash Type Result e45d90957eec7387726c6a1b174da7b566a24ff4cb060dcbcdfebb931a93ffe3 sha256 passw The fact that this is an un-salted hash makes it easy to look up. All the encoding is ...


83

It would seem that it depends on how exactly the attacker is going to bruteforce your password. However, my opinion is that in the end it doesn't matter. A serious attacker will never start from the beginning in alphanumeric order, from aaaaaaaa to 99999999, unless they know they can do that in a reasonable time. If that's going to take them a thousand ...


82

There is no method to make WEP uncrackable, or at least secure. So I suggest buying a new router that suports WPA2.


80

128 bits (of entropy) The main purpose of a longer password is to prevent brute force attacks. It is generally accepted that 128 bits is beyond anyone's capability to brute force, and will remain so for the foreseeable future. You see this figure in a few places, e.g. SSL ciphers with 128-bit or greater key length are considered "high security" and OWASP ...


79

What I see most commonly is allowing the authentication and signing the user in, but locking meaningful features away until the email is verified. You should bubble up an error reminding the user to re-send an activation email if they try to access one of the restricted features. It is poor design to ever lie to a user - if they submit the correct username ...


78

I think Trey Blalocks answer is great, but I would like to complement it with some math. If your password is randomly picked from the 171,476 words in the Oxford English Dictionary you get log2(171476) or about 17.4 bits of entropy. Lets assume there is about 4 natural leet substitution in the average word. Randomly either doing or not doing each ...


77

You don't need to bruteforce a hash to steal a password. A website might be compromised by an attacker so that they can read the passwords directly from the login form, in plain text. Or the website owner might be doing this, they could always do it if they wanted to, it's up to you whether you trust the owner or not (you wouldn't want to use the same ...


74

There are two different passwords that access different functions. If an attacker has the admin password, then he / she can change the SSID, WiFi password, and any other settings on the WiFi router. To fix: ensure your WiFi security setting is WPA or WPA2. Then change the WiFi password to a long one (at least 12 characters, more is better) with special ...


72

TL;DR: I don't need to recover YOUR password, I just have to find a string that generates the same hash, and as you don't control the hash the website developer uses until they all use a secure one, it doesn't help as much as it costs. And if I'm after you I keep hacking websites you use until I find a weak one. Or I use another method. Relevant XKCD: ...


70

If an attacker has found out your password, he can access the system up until you change the password. Changing passwords often prevents attackers that already have your password to have undetected access indefinitely. Now, if your password is secret-may16 and the attacker is locked out when you change your password, he is certainly going to try secret-...


70

It's a base64 unsalted sha256 hash. It's not double encryption, but merely an unneeded encoding. An unsalted hash means it's trivial to just search the hash on Google and probably it will find the result.


68

The main problem with passwords is not password complexity, but password reuse (obligatory xkcd). One service leaks logins and passwords, suddenly lots of providers see a surge on account hijacks. Why? Because we humans cannot remember dozens of different passwords, so we create one password for common services, and one for special ones. But most of us will ...


67

Yes, they were likely able to crack many of the passwords in a short time. From the official Yahoo statement: For potentially affected accounts, the stolen user account information may have included names, email addresses, telephone numbers, dates of birth, hashed passwords (using MD5) and, in some cases, encrypted or unencrypted security questions and ...


66

I would figure there are two ways they've come up with the information that they drew that conclusion from. They ran the net accounts /domain command on a users computer which dumped the password complexity requirements for your organization (assumes Windows / Active Directory) They successfully brute forced (or guessed) user passwords because they were ...


64

It always depends on what you compare it with! What is the realistic alternative, that users would actually use, to using this card? Clearly, 4uR=?F133Y9Yi31 is a much better password than HELLOWORLD. If you are giving this card to a non-techie whos not going to pick good passwords or use a password manager anyway, then it's an improvement. On the other ...


59

How are plaintext and hashes compared? During the brute force attack, words from the dictionary are hashed with the correct hash algorithm and salt, and then compared to the hash in the database dump. So the attacker needs to know not only the hash value itself, but the algorithm and the salt. How does the attacker know the salt? The salt is generally ...


57

One related question that you missed in your list is this one: How critical is it to keep your password length secret? The accepted answer there (disclaimer: mine) shows that if you have a password scheme which allows all 95 printable ascii characters, then the key space ramps insanely quickly every time you increase the length of the password by 1. You ...


55

I'm choosing to assume you're asking why it's a risk rather than how to hack. GPUs are very good at parallelising mathematical operations, which is the basis of both computer graphics and cryptography. Typically, the GPU is programmed using either CUDA or OpenCL. The reason they're good for brute-force attacks is that they're orders of magnitude faster than ...


53

It is not necessarily a bad idea. The attacker can know the password is in that format, considering the 4 words are random enough. But here is the thing, there are other good ways to make a memorable strong password. Limiting your users to the one you like is not very nice. For example I use password manager with truly random long passwords, which is even ...


50

Actually, it's as bad as a full hash leak. Hash-cracking is done by: Generating password candidates Hashing them Comparing the resulting hashes to the hash you want to crack None of those steps will be slower in case of a partial hash leak, so this is very similar to a full hash leak speed-wise. Please note that if the partial hash output is not long ...


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