7-zip Hash

Technical details, regex signatures, and cracking commands for the 7-zip algorithm.

Regex Identification Signature:

                        \$7z\$[0-9]\$[0-9]{1,2}\$[0-9]{1}\$[^$]{0,64}\$[0-9]{1,2}\$[a-f0-9]{32}\$[0-9]{1,10}\$[0-9]{1,6}\$[0-9]{1,6}\$[a-f0-9]{2,}
                    

Hashcat Command (Mode: 11600):

John the Ripper Command:

← Back to Hash Identifier

What is 7-zip?

The **7-Zip** archive format, introduced in 1999 by Igor Pavlov as part of the open-source *7-Zip* compression utility, employs a **cryptographic hash-based integrity verification system** rather than a dedicated cryptographic hash function like SHA-256 or BLAKE3. The format leverages the **CRC32** (Cyclic Redundancy Check) algorithm for basic integrity checks and optionally integrates **SHA-256** (or other SHA variants) for stronger verification in newer versions. Structurally, the 7-Zip format is a **multi-layered container** supporting multiple compression algorithms (e.g., LZMA, LZMA2, PPMd) and encryption modes (AES-256, Twofish, etc.), with hashes embedded in the archive’s header metadata to ensure data integrity. While not designed as a standalone cryptographic primitive, its hash mechanisms serve as a **lossless verification tool** for archive consistency, where the hash of the decompressed data is compared against the stored checksum to detect corruption. This design prioritizes **compression efficiency** over cryptographic security, making it unsuitable for password hashing or digital signatures.

The **vulnerability of 7-Zip’s hash mechanisms to cracking** stems from fundamental design flaws and computational optimizations. CRC32, the primary hash in legacy 7-Zip archives, is **not collision-resistant** and suffers from **preimage attacks** due to its 32-bit output space, enabling brute-force collisions in polynomial time. Even when SHA-256 is used, the absence of **salting** or **peppering** in password-protected archives makes it susceptible to **rainbow table attacks** if passwords are reused or weak. Additionally, the **compression layer** introduces a **side-channel vulnerability**: decompressing data in parallel across **multi-core CPUs or GPUs** (via optimized libraries like LZMA SDK) accelerates brute-force attacks by orders of magnitude, as attackers can test password candidates while leveraging hardware-accelerated decompression. Finally, the **lack of key stretching** in encryption modes (e.g., AES-256-CBC) allows for **GPU-optimized cracking tools** (e.g., Hashcat) to test millions of hashes per second, rendering the format **ineffective for secure password storage**—a role for which it was never intended.

Identifying 7-zip Hashes

Identifying a hash blindly is often difficult because multiple algorithms can output strings of the exact same length. For example, a standard 32-character hexadecimal string could be MD5, NTLM, MD4, or LM. To definitively identify 7-zip, security researchers analyze the hash against a strict regular expression (regex) signature (shown above) to find structural matches.

How to Crack 7-zip

If you need to recover the plaintext password for a 7-zip hash during a penetration test or forensics investigation, you must supply the correct module ID to your cracking software. Use the exact commands provided at the top of this page to target the hash successfully.