Quais são algumas ferramentas e técnicas comuns para hash cracking?

Hashes are very important to maintain data integrity, use hash functions that are securely tested and guarantee a high level of reliability. For example: Whirlpool, BLAKE2, Skein and SHA-512, however, mainly evaluate the viability of the functions, as they can generate bottlenecks in the application, as it requires many resources for processing.

As an ethical hacker, I've often encountered various hashing algorithms in different environments. For instance, during a penetration test on a corporate network, I discovered that the application was using MD5 hashes for storing passwords. This prompted me to quickly switch to using hashcat, as I knew that MD5 was vulnerable to collisions. By identifying the format and understanding its weaknesses, I was able to efficiently crack the hashes and demonstrate the importance of using stronger algorithms like SHA256 or bcrypt in production environments. Tools such as hash-identifier were instrumental in helping me identify the hash type quickly, allowing me to focus my cracking efforts effectively.

The SHA-3 is currently a robust choice, offering flexibility in output sizes. In password hashing, bcrypt and Argon2 shine, prioritizing resistance against attacks. Additionally, exploring adaptive hashing techniques like scrypt adds an extra layer of defense. Being aware of hash formats is also crucial; JSON Web Tokens commonly employ HMAC-SHA256, enhancing security in web applications. The choice of encoding formats, like base64, further influences hash readability and data transfer efficiency.

Hash cracking involves reversing cryptographic hash functions to retrieve original input data like passwords. Common tools include John the Ripper, Hashcat, Cain & Abel, RainbowCrack, Ophcrack, and THC Hydra. Techniques include dictionary attacks, which use lists of potential passwords, and brute force attacks, which try all possible combinations. Rainbow table attacks use precomputed tables for faster cracking. Hybrid attacks combine dictionary and brute force methods, while rule-based and mask attacks customize password candidates. Phishing tricks users into revealing passwords, and cryptanalysis exploits algorithm weaknesses.

Before cracking hashes, it's crucial to identify their type and format. MD5 and SHA1 are weak, while SHA256 and bcrypt are more secure. Hash types vary by system: Windows uses NTLM, Linux uses shadow files, and web apps use salted hashes. Tools like hash-identifier and hashcat-utils can help identify hashes.

In my experience, I once faced a situation where a target application had implemented a robust password policy, resulting in complex and lengthy passwords. Despite this challenge, I employed John the Ripper to perform a brute-force attack tailored to the character set defined by the company’s password policy. I utilized a custom rule set to optimize the attack, significantly reducing the time required to find a matching hash. This experience underscored the effectiveness of customizing brute-force parameters, even against strong passwords, and it highlighted the importance of maintaining password complexity while being aware of the potential for successful cracking through brute-force methods.

Use seclist wordlists or the native ones that come with Parrot or Kali Linux, however attacks based on wordlists are not very effective in scenarios where you are unaware of the password policy imposed, the type of data you have in that specific hash and the tool you are using.

Dictionary attacks involve comparing hashed passwords against a precomputed list of common hashes using tools like John the Ripper or hashcat. They are fast and straightforward but struggle with complex, uncommon, or salted passwords. Wordlists for these attacks can be found online or created manually.

Brute force attacks are one of the main techniques when breaking Hash, however it requires adequate processing, many hire VPS with high processing, such as OVHCloud and other existing clouds.

Brute force attacks, vital in hash cracking, often demand robust processing power. Many turn to providers like OVHCloud for high-performance VPS solutions. However, cost considerations arise with premium instances. Additionally, providers monitor for misuse, risking account suspension. Reliance on external clouds also raises data privacy concerns. Geographic distance may impact network latency, affecting attack efficiency. Despite challenges, VPS rentals remain popular for their accessibility and processing capabilities.

Brute-force attacks involve trying every possible character combination to match a hash, which is time-consuming and resource-intensive. Tools like John the Ripper and hashcat can perform these attacks, specifying character sets and patterns. However, they are ineffective against strong passwords or salted hashes.

It is important to know whether the Hashes are passwords or just specific information, however it is important to add syntaxes to assist in your brute force attack, mainly to save time and resources, adapt specific password policies and increase the efficiency of the attack.

Rule-based attacks enhance hash cracking by applying modifications like appending, prepending, changing case, reversing, duplicating, or deleting characters, as well as using leet speak or common substitutions. Tools like John the Ripper and hashcat facilitate these attacks with predefined or custom rules, improving the chances of cracking complex passwords.

A rainbow table attack is similar to a dictionary attack, first you must capture a password hash then you compare that hash to a list of previously generated password hashes based on a list of passwords. If your hash is a match to one in your rainbow table, you can easily and quickly find the plaintext password. You can find rainbow tables online on GitHub or use tools to generate your own based on a password dictionary.

Rainbow tables are precomputed databases of hash and plain text password pairs, allowing quick password cracking by bypassing real-time hashing calculations. They require significant storage, are specific to hashing algorithms and character sets, and are ineffective against salted hashes. Tools like Ophcrack and rcracki-mt can be used for rainbow table attacks.

Hybrid attacks combine techniques like dictionary attacks with rules or brute-force with wordlists to enhance success and efficiency. Tools like John the Ripper and hashcat can be used for these attacks, but they require more time, resources, and are vulnerable to anti-cracking measures. Quality of wordlists and rules is crucial.

In my opinion, most useful tools is Hashcat and Johny the Ripper for ofline, and Crackstation for online hash cracking. I will advise to use different methods for cracking a hash, since depending on the approach to security when creating a password, it will require the use of different techniques like Brute-force, hybrid brute-force, dictionary attacks, Raindow table etc.

Password cracking is a simple equation of password complexity vs cracking power and time. The simpler the password, the less cracking power and time required to crack. However, the power and time required to crack a password can increase exponentially given the complexity and size of a password. There are easy online tools to guess how much time/energy would be required to crack a password. You can use these to influence password policy guidelines and show complexity impact to managers.

Hash cracking is vital in cybersecurity for testing hash function strength. Common tools include John the Ripper, an open-source tool supporting various hash types with dictionary and brute force attacks, and Hashcat, known for its speed and GPU acceleration. Cain & Abel combines multiple techniques on Windows, while RainbowCrack uses precomputed rainbow tables. Techniques involve dictionary attacks using predefined password lists, brute force attempts of all combinations, and hybrid approaches mixing dictionary and brute force methods, enhancing password strength testing and vulnerability identification.

Consider leasing Server's with multiple GPU's. This can dramatically speed up the rate at which you can crack passwords. An adversary will have as much time and resources as they want to crack a password, factoring this into a penetration test provides valuable insights.