840 Brute Force

[Leroy Turcios]

Incryptography, a brute-force attack consists of an attacker submitting many passwords or passphrases with the hope of eventually guessing correctly. The attacker systematically checks all possible passwords and passphrases until the correct one is found. Alternatively, the attacker can attempt to guess the key which is typically created from the password using a key derivation function. This is known as an exhaustive key search. This approach doesn't depend on intellectual tactics; rather, it relies on making several attempts.[citation needed]

A brute-force attack is a cryptanalytic attack that can, in theory, be used to attempt to decrypt any encrypted data (except for data encrypted in an information-theoretically secure manner).[2] Such an attack might be used when it is not possible to take advantage of other weaknesses in an encryption system (if any exist) that would make the task easier.

When password-guessing, this method is very fast when used to check all short passwords, but for longer passwords other methods such as the dictionary attack are used because a brute-force search takes too long. Longer passwords, passphrases and keys have more possible values, making them exponentially more difficult to crack than shorter ones due to diversity of characters.[3]

Brute-force attacks can be made less effective by obfuscating the data to be encoded making it more difficult for an attacker to recognize when the code has been cracked or by making the attacker do more work to test each guess. One of the measures of the strength of an encryption system is how long it would theoretically take an attacker to mount a successful brute-force attack against it.[4]

Brute-force attacks are an application of brute-force search, the general problem-solving technique of enumerating all candidates and checking each one. The word 'hammering' is sometimes used to describe a brute-force attack,[5] with 'anti-hammering' for countermeasures.[6]

Brute-force attacks work by calculating every possible combination that could make up a password and testing it to see if it is the correct password. As the password's length increases, the amount of time, on average, to find the correct password increases exponentially.[7]

The resources required for a brute-force attack grow exponentially with increasing key size, not linearly. Although U.S. export regulations historically restricted key lengths to 56-bit symmetric keys (e.g. Data Encryption Standard), these restrictions are no longer in place, so modern symmetric algorithms typically use computationally stronger 128- to 256-bit keys.

However, this argument assumes that the register values are changed using conventional set and clear operations, which inevitably generate entropy. It has been shown that computational hardware can be designed not to encounter this theoretical obstruction (see reversible computing), though no such computers are known to have been constructed.[citation needed]

As commercial successors of governmental ASIC solutions have become available, also known as custom hardware attacks, two emerging technologies have proven their capability in the brute-force attack of certain ciphers. One is modern graphics processing unit (GPU) technology,[9][page needed] the other is the field-programmable gate array (FPGA) technology. GPUs benefit from their wide availability and price-performance benefit, FPGAs from their energy efficiency per cryptographic operation. Both technologies try to transport the benefits of parallel processing to brute-force attacks. In case of GPUs some hundreds, in the case of FPGA some thousand processing units making them much better suited to cracking passwords than conventional processors. For instance in 2022, 8 Nvidia RTX 4090 GPU were linked together to test password strength by using the software Hashcat with results that showed 200 billion eight-character NTLM password combinations could be cycled through in 48 minutes.[10][11]

Various publications in the fields of cryptographic analysis have proved the energy efficiency of today's FPGA technology, for example, the COPACOBANA FPGA Cluster computer consumes the same energy as a single PC (600 W), but performs like 2,500 PCs for certain algorithms. A number of firms provide hardware-based FPGA cryptographic analysis solutions from a single FPGA PCI Express card up to dedicated FPGA computers.[citation needed] WPA and WPA2 encryption have successfully been brute-force attacked by reducing the workload by a factor of 50 in comparison to conventional CPUs[12][13] and some hundred in case of FPGAs.

Advanced Encryption Standard (AES) permits the use of 256-bit keys. Breaking a symmetric 256-bit key by brute force requires 2128 times more computational power than a 128-bit key. One of the fastest supercomputers in 2019 has a speed of 100 petaFLOPS which could theoretically check 100 trillion (1014) AES keys per second (assuming 1000 operations per check), but would still require 3.671055 years to exhaust the 256-bit key space.[14]

An underlying assumption of a brute-force attack is that the complete key space was used to generate keys, something that relies on an effective random number generator, and that there are no defects in the algorithm or its implementation. For example, a number of systems that were originally thought to be impossible to crack by brute force have nevertheless been cracked because the key space to search through was found to be much smaller than originally thought, because of a lack of entropy in their pseudorandom number generators. These include Netscape's implementation of Secure Sockets Layer (SSL) (cracked by Ian Goldberg and David Wagner in 1995) and a Debian/Ubuntu edition of OpenSSL discovered in 2008 to be flawed.[15][16] A similar lack of implemented entropy led to the breaking of Enigma's code.[17][18]

Credential recycling is the hacking practice of re-using username and password combinations gathered in previous brute-force attacks. A special form of credential recycling is pass the hash, where unsalted hashed credentials are stolen and re-used without first being brute forced.[19]

In case of an offline attack where the attacker has gained access to the encrypted material, one can try key combinations without the risk of discovery or interference. In case of online attacks, database and directory administrators can deploy countermeasures such as limiting the number of attempts that a password can be tried, introducing time delays between successive attempts, increasing the answer's complexity (e.g., requiring a CAPTCHA answer or employing multi-factor authentication), and/or locking accounts out after unsuccessful login attempts.[21][page needed] Website administrators may prevent a particular IP address from trying more than a predetermined number of password attempts against any account on the site.[22] Additionally, the MITRE D3FEND framework provides structured recommendations for defending against brute-force attacks by implementing strategies such as network traffic filtering, deploying decoy credentials, and invalidating authentication caches.[23]

In a reverse brute-force attack, a single (usually common) password is tested against multiple usernames or encrypted files.[24] The process may be repeated for a select few passwords. In such a strategy, the attacker is not targeting a specific user.

This is an old attack method, but it's still effective and popular with hackers. Because depending on the length and complexity of the password, cracking it can take anywhere from a few seconds to many years.

Breaking into online accounts can be like cracking open a bank vault: everything from bank accounts to tax information can be found online. All it takes is the right break-in for a criminal to steal your identity, money, or sell your private credentials for profit. Sometimes, sensitive databases from entire organizations can be exposed in corporate-level data breaches.

If you run a website and become a target of vandalism, a cybercriminal might decide to infest your site with obscene content. This might include text, images, and audio of a violent, pornographic, or racially offensive nature.

Dictionary attacks: in a standard attack, a hacker chooses a target and runs possible passwords against that username. These are known as dictionary attacks. Dictionary attacks are the most basic tool in brute force attacks. While not necessarily being brute force attacks in themselves, these are often used as an important component for password cracking. Some hackers run through unabridged dictionaries and augment words with special characters and numerals or use special dictionaries of words, but this type of sequential attack is cumbersome.

Hybrid brute force attacks: these hackers blend outside means with their logical guesses to attempt a break-in. A hybrid attack usually mixes dictionary and brute force attacks. These attacks are used to figure out combo passwords that mix common words with random characters. A brute force attack example of this nature would include passwords such as NewYork1993 or Spike1234.

Reverse brute force attacks: just as the name implies, a reverse brute force attack reverses the attack strategy by starting with a known password. Then hackers search millions of usernames until they find a match. Many of these criminals start with leaked passwords that are available online from existing data breaches.

Automated tools help with brute force attacks. These use rapid-fire guessing that is built to create every possible password and attempt to use them. Brute force hacking software can find a single dictionary word password within one second.

Combining the CPU and graphics processing unit (GPU) accelerates computing power. By adding the thousands of computing cores in the GPU for processing, this enables the system to handle multiple tasks at once. GPU processing is used for analytics, engineering, and other computing-intensive applications. Hackers using this method can crack passwords about 250 times faster than a CPU alone.

3a8082e126