An attack using every possible input to attempt to produce the correct output. Typically the method of last resort when no weakness allows the use of a more restricted input set. E.g. trying all possible (or likely) passwords, in an attempt to guess the correct one.

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My server has been brute forced what now? [duplicate]

I have installed a raspberry pi for fun at home. I opened the port 22 and this morning I was concerned about someone brute forcing my server. I ran this query : cd /var/log;zgrep ssh auth*|grep ...
1
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3answers
211 views

Touch tone phone username and password

I just got off the phone with Fidelity, who manage the health benefits for the company where I work. Before talking to a person, I was prompted to enter my username and password on the numeric keypad: ...
20
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2answers
14k 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 ...
2
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2answers
824 views

Can you crack a Mailinator “Alternate Inbox Name?”

From their FAQ: What are "Alternate Inbox Names" ? There are 2 ways to get email into any given inbox. When you check an inbox, listed at the top is the Alternate Inbox name. Emailing that alternate ...
0
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1answer
65 views

Find hash-function if original and hash are given? [duplicate]

I was thinking whether or not you can find the hash function(s) used if you have the original message and the hash. So assume that no salt is used during the hashing process, just multiple hashing and ...
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1answer
755 views

How do we estimate the time taken to crack a hash using brute force techniques

A German hacker famously managed to brute force crack a 160 bit SHA1 hash with passwords between 1 to 6 digits in 49 minutes. Now keeping everything constant (hardware, cracking technique - here ...
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4answers
1k views

Can I brute-force a password hash even if I don't know the hash-algorithm used?

Can I brute-force a password hash even if I don't know the underlying algorithm? For example if I get hold of a database with password hashes and the used hash algorithm is unknown, like a random ...
12
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4answers
576 views

How should I secure a contact form that appears on every page of a website?

My client has a small "Contact Us" form on every page of their website. They are adamant about not including CAPTCHA verification on these forms, to keep them easy to use, but I feel it is my ...
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8answers
126k views

Where can I find good dictionaries for dictionary attacks?

I’m wondering where I can find good collections of dictionaries which can be used for dictionary attacks? I've found some through Google, but I’m interested in hearing about where you get your ...
33
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2answers
46k views

How to estimate the time needed to crack RSA encryption?

How to estimate the time needed to crack RSA encryption? I mean the time needed to crack Rsa encryption with key length of 1024, 2048, 3072, 4096, 5120, 6144, 5120, 7168, 8192, 9216, 10240, 11264, ...
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4answers
583 views

Can't brute force password cracking somehow be throttled?

Online articles mention the importance of a strong password and suggest that hacking tools allows bad guys to attempt millions of passwords per second. I am wondering why OSes and websites and such ...
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2answers
270 views

How to make an efficient bruteforce attack on Windows? [closed]

I've been trying to figure out a way to efficiently bruteforce on Windows, but the method I currently have isn't very efficient. I did some profiling and found out that on average it can go through ...
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0answers
948 views

Brute-Force/Dictionary attack against encypted file using PBKDF2 key derivation

I have been following this very useful post by Thomas. My use case is slightly different. I am developing a mobile application which requires some sensitive data to be stored on the device in a SQLite ...
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1answer
679 views

Harden a server against mass SSH DoS attacks

How can a Linux server be protected against an attacker that tries to open a large number of SSH sessions (probably trying to brute force a password) that no ports remain to be able to legitimately ...
2
votes
1answer
257 views

Is there an equation to calculate the number of instances of a series of characters exist in a given key space?

If I'm using 16-18 character-length passwords with 94 different possible values-per-character (lower alphas, upper alphas, numbers, and special characters), is there an equation I can use to calculate ...
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1answer
73 views

How many possible symbols and punctuations in a password? [closed]

I want to compute the possible combinations of a password consists of 8 digits of: alphabetical letters (26), numbers (0-9), symbols and punctuations. In order to compute this, I have to know the ...
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5answers
3k views

Do non-keyboard characters make my password less susceptible to brute forcing?

I can put characters in my password for which there are no keys on a keyboard. On Windows, Alt+#### (with the numpad) inserts the character for whatever code you type in. When I put this in a ...
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votes
2answers
24k views

Remove Password Protection from XLS Document

Similar to what is listed here, http://datapigtechnologies.com/blog/index.php/hack-into-a-protected-excel-2007-or-2010-workbook/, is there a way to remove the password from an XLS (Excel 2003) ...
3
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1answer
282 views

Better than brute-force way to find the “lowest” sha1 hash?

While pointing out a SQL injection flaw on another question, I was able to show that an arbitrary sha1 hash could be inserted into a query such that it would be taken for a real hash, and was ...
2
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1answer
142 views

Username Enumeration as a Threat

I have found a Username Enumeration Vulnerability through which I am able to determine whether a particular user is registered with that site. While trying to brute force, after 5 attempts it asks for ...
5
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3answers
3k views

What are the odds of brute-forcing an archive with 256-bit encryption?

I have a file (a stand-alone archive). I lost the password to it, but it has been encrypted using 256-bit encryption. The password is some 20-odd characters long (including non-alphanumeric ...
2
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1answer
159 views

Given a hash, salt, charset and password length, how do you get the password without brute-forcing it?

I got that question on an exercise and I'm not sure what to answer. Without conventional brute-forcing and without a rainbow table, how could I find out the password? An improved brute-force ...
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2answers
102 views

How do you overcome the problem of the salt being public and known by the attacker? [duplicate]

I believe that when adding a salt to the password you need to store the values so you can compute the hash again. But, what does happen if the attacker get the salt? How is it possible to add value ...
0
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1answer
44 views

Does restarting an encrypted session increase security and deter attacks?

When a user initiates a SSH connection for example, keys are exchanged and a session is established with a new "passphrase" each time. If an attacker were to attempt to brute force this connection, ...
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10answers
4k views

Best password strength checker

In XKCD #936: Short complex password, or long dictionary passphrase? Jeff claimed that password cracking with "dictionary words separated by spaces", or "a complete sentence with punctuation", or ...
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1answer
10k views

Forgot password to 7-Zip archive

I think I already know the answer to this question, but I thought I'd ask the experts anyway. A few months back, I created a password-protected 7-Zip archive which housed the source code of a simple ...
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1answer
64 views

Is encryption less resistant to brute-forcing compared to hashing?

I understand that a hashing algorithm like bcrypt uses several rounds of hashing to make it computationally expensive for a brute-force attack. How does encryption work against a brute-force attack? I ...
3
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3answers
283 views

Could using a generated key from an online service be considered a risk?

With some colleagues we're having a debate regarding the randomkeygen.com website. I do think that there is a security risk using the generated keys of this (or any of this kind) website. Why ? ...
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2answers
256 views

How do you know if blowfish key is correct?

Encryption novice here so maybe this question makes no sense... Obviously if you know what the clear text is and it decrypts right, you have it. But if someone is running through keys to break the ...
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8answers
3k views

With which algorithm I can prevent a brute force on a login?

I want make my software more secure. I want prevent it from brute force attack. I know that a strong password is the best but I can not control it. The algorithm must scale from a very small system ...
0
votes
1answer
133 views

What is the best way to generate a password/pin like string using brute force method? [closed]

I have a string of 7 characters. I'm supposed to generate all the combinations. But some combinations are more likely than others, I would like the more likely ones to be generated first. If I ...
15
votes
3answers
2k views

Why check to see if a password is already used by another user?

This is coming from a joke originally in French: Enter your password. carrot Sorry, your password must be more than 8 characters. carottegéante (giant carrot) Sorry, your ...
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1answer
1k views

How many possibilities can today's computers check (per second) in a SHA512 hash of a 50-byte-long random entry? [closed]

The problem I want to avoid is "brute force" attacks against a database. So if I add a 50-byte-long cryptographically random salt to my information (which I don't need to retrieve, just its hash) - is ...
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1answer
3k views

Hydra bruteforce is giving wrong passwords. Can't seem to work any help? [closed]

Ok so what im actually trying to do is to bruteforce my own account on some website just to check myself . This is NOT for illegal steps or use , im trying to crack my OWN password , and im trying to ...
1
vote
1answer
204 views

What is the strength of the key derivation function on Android device encryption?

What is is strength of the key derivation? Specifically, how many milliseconds or microseconds would it take a desktop computer to check a guessed password to see if it is a match? I am aware this ...
4
votes
3answers
243 views

Is there any reason in particular encryption keys aren't arbitrarily large?

It's my understanding that the more bits an encryption key has, the longer it takes to break the encryption. What is the down side of having a larger encryption key or why don't we see keys of size ...
0
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1answer
172 views

How can brute force scripts tell once they're found the correct key?

If you have a random block of data and you encrypt it with a key, how can a brute force script tell when it has found the correct key? Is it possible without some sort of reference to the original ...
25
votes
7answers
21k views

Invalid users trying to log in to my server

I'm seeing a lot of log entries that appear to be failed login attempts from unknown IP addresses. I am using private and public keys to log in with SSH but I have noticed that even with private ...
3
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3answers
394 views

How to optimize compressed file cracking?

I'm currently doing research on cracking encrypted, compressed files (specifically: uif, zip, 7z, dmg). Looking at all the utilities out there, it seems the time it takes to crack something is ...
6
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3answers
969 views

NTLMv2 resistance to bruteforcing

I have a question regarding NTLMv2 resistance to password bruteforcing. I know that some modern graphic processors (like Radeon 6990) are able to calculate billions hashes per second and crack NTLM ...
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3answers
428 views

Brute Force In Order Or Random?

Which is faster, on average to find the original plain text of a hash: brute force in-order, or with random plaintexts?
13
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2answers
10k views

What's the purpose? Strange login attemps “sshd[***] Received disconnect from **.**.**.**: 11: Bye Bye [preauth]”

I've seen something like: sshd[***]: Invalid user oracle from **.**.**.** // 1st line sshd[***]: input_userauth_request: invalid user oracle [preauth] // 2nd line ...
8
votes
7answers
826 views

How can I prevent users from using bad passwords in my web application?

There is a long discussion on whether it's the responsibility of the user or the system administrator to deal with the strength of the password. Obviously, the password is a very private thing, but ...
2
votes
3answers
618 views

Is there an internal equivalent to fail2ban?

fail2ban is a protection against brute-force that locks a user out after a definable maximum failed login-attempts. But if a user already has access to a server with another username already fail2ban ...
0
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1answer
8k views

Has the WPS brute-force cracking issue been fixed?

I have heard a rumor that the WPS brute force attack doesn't work on newer devices, and that you now have to try all 10^7 PINs to find the correct one. Is that true?
4
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2answers
157 views

How can you I detect low frequency brute forcing over multiple connections?

While I realize that servers can easily detect brute forcing strategies via a single I.P, it seems that servers would be vulnerable to a distributed attack from a botnet, with each computer attempting ...
2
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2answers
181 views

Slowing down repeated password attacks

I've been reading suggestions to use time-consuming formulas for checking passwords from login attempts, so that repeated attacks will be slowed down. Wouldn't it suffice to just sleep a bit in the ...
30
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5answers
2k views

What are the security implications of storing password blacklist?

I want to add a password blacklist that would prevent the 1000 most common passwords from being used in order to mitigate shallow dictionary attacks. Is there any negative implication of storing this ...
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votes
2answers
1k views

Automated URL Discovering

I built a simple server containing static files at /files/ and I'm attempting to discover them using automated tools. I'm using wfuzz to brute force on the URL but is that the only way? Is there any ...
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1answer
778 views

How bruteforce works code wise

I was wondering how bruteforce methods work from a code level. How does the code get access to a login page for example and insert information into the necessary fields? And is the code able to ...