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Questions tagged [password-cracking]

for questions relating to the cracking of passwords and the practices to mitigate against passwords being cracked.

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155
votes
17answers
21k views

Is the BBC’s advice on choosing a password sensible?

In this article on the BBC’s website they offer advice on how to develop a password. The steps are as follows. Step 1: Choose an artist (a recording artist I presume) Lets choose as an example ...
101
votes
3answers
18k views

Why is Sojdlg123aljg a common password?

I was going through the list of top 100K passwords and found Sojdlg123aljg near the top of the list. Does anyone have any idea why this is such a common password?
90
votes
10answers
13k views

Is there a threshold for a password so long it doesn't get any more secure or even becomes insecure?

I always hear "A long password is good, a longer password is better". But is there such a thing as a "Password is so long it is becoming unsafe" or "Password is long enough, making it longer won't ...
81
votes
11answers
50k views

Why is client-side hashing of a password so uncommon?

There are very few websites that hash the users password before submitting it to the server. Javascript doesn't even have support for SHA or other algorithms. But I can think of quite a few ...
77
votes
4answers
20k views

How long will it take to crack the passwords stolen in the Yahoo hack announced 14 Dec 2016?

Apparently Yahoo was hacked yet again with up to a billion user accounts being compromised. The article says Yahoo uses MD5 for password hashing. Are the hackers likely to be able to crack the ...
75
votes
9answers
16k views

Can one tell if a password guess was close by the hash result?

I have been reading about password management lately (very interesting stuff!) and was wondering how different the hashes would be for similar strings. Is it possible to know if a password guess was ...
63
votes
5answers
6k views

Do 2FA sites leak info by confirming a correct password guess?

Here's my relatively layman's view of the issue. Many websites tout multifactor authentication (MFA) as an enormous boost to the security of users' accounts, and it can be if implemented properly. ...
63
votes
1answer
13k views

I found a password with hashcat, but it doesn't work

My assignment required me to find the password for a PowerPoint file (97 - 2003, v. 8.0 - v. 11.0). I used office2john.py to retrieve the hash, and I removed the file name. The hash is: $...
60
votes
3answers
15k views

Are leet passwords easily crackable?

Making a strong password AND remembering it is like eating while talking. You choke. So the same thing might happen if you have a p455w0(R).|L1K3thys and someone cracks it. I'm just not sure if it's ...
55
votes
9answers
13k views

Are randomly-generated passwords starting with “a” less secure?

I generated a password recently for a new account and the first three characters were "aa1". After exhausting all other attacks, a cracker would start brute forcing. On the assumption they'd start ...
54
votes
3answers
10k views

Secret salts; why do they slow down attacker more than they do me?

When studying Dan Boneh's slides for 'Session Management and User Authentication' (2011) he mentions 'secret salts' on the slide 'Further defences' (slide 48 out of 58). He suggest to store in the ...
54
votes
7answers
10k views

Is it possible to determine password strength without knowing the password?

I have just got some report of a penetration test and one of the recommendations was to strengthen passwords. I however realized that no passwords were provided for the testers, and I wanted to find ...
52
votes
7answers
25k views

How are GPUs used in brute force attacks?

I have read that GPUs can be used in brute force attacks? But how can this be done and is there a need for any other hardware devices (hard disks for instance)? Note: I'm more interested in web ...
51
votes
7answers
15k views

Is this password scheme legit?

I received an invitation for an IT security fair (https://www.it-sa.de/en). They additionally delivered a password "Kryptonizer". That is a little card to hang on your keychain with the following (...
44
votes
7answers
6k views

Are partially typed passwords a potential security risk?

I just sat down at my work computer and began to unlock it by typing in my password, I got 6 of the 8 characters in and decided I wanted coffee and walked away to get it. I came back, realized I left ...
42
votes
7answers
73k views

Somebody hacked my router and changed my wifi SSID

One of my neighbours hacked the password of my router and he uses my limited internet package. I change the wifi SSID almost daily, but he can hack it easily. Today, he changed the SSID to a hate ...
41
votes
5answers
258k views

How to recover a lost zip file password?

I have some files I was given by my teacher at University, I could chase him up, but I may as well try getting blood from a stone, his response rate isn't great and I completed my degree a year ago! ...
39
votes
14answers
14k views

How can I make a strong password that's easy to remember? Is the 4 Word method safe? [duplicate]

I have heard of the method of using 4 random dictionary words, it gives you lots of characters and is easy to remember. But that seems to be open to dictionary attacks, especially if the attacker has ...
39
votes
3answers
60k views

How secure is 7z encryption?

I have a text file in which I store all my bank details. I compress and encrypt it with 7-Zip using the following parameters: Compression parameters: Archive format: 7z Compression level: Ultra ...
37
votes
5answers
11k views

How can I prove this site has a huge security weakness?

Disclaimer: I'm a computer programmer, not a security analyst or anything to do with security. I have zero experience in the world of cryptography, so bear with me please. Situation: I was given the ...
36
votes
12answers
10k views

Is it acceptable practice to only increment a number when changing a password?

Note: I'm not asking about this password scheme is the best or not (of course it isn't); I'm asking about its theoretical or practical secureness relative to the optimal password scheme based on the ...
33
votes
2answers
37k views

Why are GPUs so good at cracking passwords?

What is it about GPUs that lets them crack passwords so quickly? It seems like the driving force behind adopting good key-derivation functions for passwords (bcrpyt, PBKDF2, scrypt) instead of ...
30
votes
9answers
7k views

What considerations do I need to keep in mind when enforcing passphrases?

According to XKCD: Password Strength, if the password consists of “four random common words”, it will be secure and memorable. I want to make a web application and make users create their passwords ...
29
votes
6answers
5k views

The most secure way to handle someone forgetting to verify their account?

Suppose we send out email verification to new subscribers that where they have to click on a link to verify their account. Suppose they forget to verify it, and later try to login. Should the error ...
29
votes
4answers
10k views

Is randomly generating passwords from an assortment of dictionary words cryptographically secure? [duplicate]

We should all know the XKCD comic on password strength, suggesting (appropriately) that a password based on multiple common words is more secure and memorable than a password such as Aw3s0m3s4u(3 or ...
29
votes
5answers
2k views

Would turning a Diceware phrase into a sentence decrease its security?

Diceware passphrase lengths are on the rise - up to six or seven words now. The old adage that passphrases are easier to remember may be true for shorter phrases, but six truly random words can be ...
28
votes
2answers
4k views

Is it possible for my password to have more than one password combination?

Can my password have more than one password combination? I read up on physical combination locks (the lock you open with numbers) and I learned that a combination lock can have more than one ...
27
votes
12answers
17k views

Reusing passwords that can possibly never be cracked

Reusing passwords pose as a terrible risk for users because in the event of a data breach, with the passwords not being stored securely enough, this means that, by default, all other services that ...
27
votes
4answers
11k views

Cracking double encrypted router password?

I noticed in the html of my router this parameter: form.addParameter('Password', base64encode(SHA256(Password.value))); So when I type in the password passw I get this via sslstrip: 2018-09-25 21:...
27
votes
4answers
6k views

Does putting salt first make it easier for attacker to bruteforce the hash?

Many recommendations for storing passwords recommend hash(salt + password) rather than hash(password + salt). Doesn't putting the salt first make it much faster for the attacker to bruteforce the ...
27
votes
1answer
10k views

How does the attacker know what algorithm and salt to use in a dictionary attack?

I am curious about password cracking methods like dictionary and brute force attacks. Nowadays passwords are stored as hashes and not plaintext on the server. Then how can the plaintext passwords in ...
25
votes
3answers
6k views

How bad would a partial hash leak be, realistically?

Even though the current recommendation for storing passwords is the usage of a slow key derivation function such as Argon2, scrypt, PBKDF2 or bcrypt1, many websites still use the traditional hash(...
25
votes
6answers
7k views

Source code as password

Passwords with a mixture of letters, numbers, and special characters are sometimes hard to remember. Is it secure to instead use a small amount of memorable source code as a 'passphrase'? As an ...
25
votes
2answers
16k views

How does WiFi password cracking work?

Let's say I have a wireless network that is password protected. What procedures can an intruder take to gain access to my wireless network, or at least be able to decipher the packets I am sending ...
24
votes
8answers
7k views

Is there a way to make a WEP-secured AP uncrackable?

For some days, I was feeling that my Internet bill was booming. Then, I recently found out that a boy near my house was accessing my router to use the Internet. Then, I read some articles how to crack ...
20
votes
5answers
7k views

Would allowing shorter passwords sometimes be more secure?

Does the act of requiring certain criteria for passwords make them easier to brute-force? It's always seemed to me that when websites limit the use of "insecure" passwords, it might make it easier ...
20
votes
5answers
19k views

How to crack a password given its hash and its salt using a more efficient method than brute force?

I have been able to crack passwords, given their salts and their hashes, by using brute force. In the first place, the length of passwords was 3 and the salt length 2: e.g., hash: rrVo/xC.s5/hQ, ...
20
votes
2answers
3k views

Store Credit Card Information in Password Manager?

For convenience purposes I manage my passwords with the password manager Bitwarden on my personal computer and smartphone with autofill function (but with asking for the master password or fingerprint ...
19
votes
6answers
3k views

Correct terminology when describing password security to layman

I am writing a page for our website which describes the measures we take to keep our customer's information secure. On this page one section describes how we keep their passwords secure. We are ...
19
votes
5answers
7k views

Someone is trying to access my mail account, what safe actions can I take?

Intro I have a free mail account on this (german) website. If I type my password wrong I get, once successfully logged in, a message telling me about my failed log-in attempt. Problem Recently I ...
16
votes
10answers
10k views

Crack hashed passwords using a known password

I'm a dev trying to deploy a new dashboard I've written at work, the old one is a mess of hacked together libraries and only about half of the codebase is still even in use (dead code everywhere that ...
16
votes
1answer
15k views

John the ripper does not crack password

I'd like to attack a self-created sha256 hash with john --wordlist= So far I've done the following: $ echo 'testpassword' | sha256sum > mypassword removed the tail of the output with vim $ cat ...
15
votes
1answer
4k views

Understanding brute-forcing algorithms [duplicate]

I've been reading up on brute-forcing techniques and possible methods of prevention, but there is one issue that I haven't been able to find a clear answer to. The way I understand it, a 'simple' ...
14
votes
3answers
16k views

Cracking MS-CACHE v2 hashes using GPU

As most people here will know, Windows caches domain/AD credentials in a format known as MS-Cache v2. Obviously, these would be excellent passwords to gain during a penetration test when local access ...
13
votes
5answers
2k views

Is it a good idea to use non-Latin Unicode characters in a password?

I've heard many suggestions as to what makes a good password (hard to guess, not a dictionary word or permutation thereof, at least a certain length, etc.) so that it cannot be cracked in a realistic ...
13
votes
3answers
3k views

How does correct grammar affect password security?

When using the XKCD password methodology, entropy is calculated solely on the basis of individual words, assuming that the individual words are independent. This is, of course, not necessarily a valid ...
12
votes
3answers
765 views

Are these claims about modern CPUs and AES decryption true?

Because of the format this question is in, it was a toss up between posting it to this site or Skeptics, but I went for here in the end because I'm probably more likely to get a definitive answer. ...
12
votes
2answers
2k views

Is KeePass's method for key derivation secure?

I'm familiar with how key derivation functions can be used to slow down brute force attacks against passwords by requiring significant computational and/or memory resources to compute the final key. ...
12
votes
2answers
15k views

What is Pixie dust attack on router?

I read an article on this site, but didn't get what I wanted so my concerns are: How does pixie dust attack work? What is the flaw that only certain routers contain to being vulnerable for Pixie-Dust ...
11
votes
3answers
553 views

Why do salts for hashing passwords need to be globally unique, not just system/site-unique?

I was reading an answer by Terry Chia to another question about the requirements for a salt, in which he/she (among others) specified that salts need to be globally unique, but don't go into any ...