MS Office ⇐ 2003 $3, SHA1 + RC4, collider #2 Hash

Technical details, regex signatures, and cracking commands for the MS Office ⇐ 2003 $3, SHA1 + RC4, collider #2 algorithm.

Regex Identification Signature:

                        ^\$oldoffice\$[34]\*[a-f0-9]{32}\*[a-f0-9]{32}\*[a-f0-9]{40}:[a-f0-9]{10}
                    

Hashcat Command (Mode: 9820):

John the Ripper Command:

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What is MS Office ⇐ 2003 $3, SHA1 + RC4, collider #2?

This cryptographic hash format, **"MS Office ≤ 2003 $3, SHA1 + RC4, collider #2"**, originates from the legacy password hashing scheme used in early versions of Microsoft Office (primarily Office 2003 and earlier) for document encryption via the **Office Open XML (OOXML) or legacy Binary Interchange Format (BIF)**. The structure combines a **SHA-1-based key derivation** (denoted by `$3`) with a **RC4 stream cipher** for symmetric encryption, where the password is first hashed via SHA-1 (160-bit output) and then used as a seed for RC4 to derive a 128-bit encryption key. The **"collider #2"** suffix refers to a specific collision-resistant variant of the hashing process, though this term is ambiguous—it may imply a proprietary modification to mitigate trivial collisions or a reference to an internal Microsoft optimization. The primary use-case was securing password-protected documents (e.g., `.doc`, `.xls`, `.ppt`) via **Office’s legacy encryption (OLE2/BIFF)**, where the hash served as a precursor to RC4-based key derivation for symmetric decryption.

The vulnerability of this scheme stems from **fundamental cryptographic flaws compounded by implementation weaknesses**. SHA-1 is now considered **broken for security purposes** due to its susceptibility to **length-extension attacks** and **collision vulnerabilities**, with preimage attacks feasible via brute-force or rainbow tables given its 160-bit output. The lack of a **salt** exacerbates offline cracking, as identical passwords produce identical hashes, enabling dictionary attacks or precomputed tables. Additionally, **RC4’s deterministic nature** (when seeded with SHA-1 outputs) allows for **GPU/ASIC-accelerated brute-force** due to its parallelizable byte-stream generation, with modern tools like **Hashcat** exploiting optimized RC4 cracking pipelines. The **"collider #2"** modification, if indeed a proprietary tweak, may not address these core issues and could introduce unintended weaknesses, while the **1990s-era design** lacks modern defenses like **Argon2, PBKDF2, or key stretching**, making it trivially crackable with sufficient computational resources.

Identifying MS Office ⇐ 2003 $3, SHA1 + RC4, collider #2 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 MS Office ⇐ 2003 $3, SHA1 + RC4, collider #2, security researchers analyze the hash against a strict regular expression (regex) signature (shown above) to find structural matches.

How to Crack MS Office ⇐ 2003 $3, SHA1 + RC4, collider #2

If you need to recover the plaintext password for a MS Office ⇐ 2003 $3, SHA1 + RC4, collider #2 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.