Microsoft Office 2010 Hash

What is Microsoft Office 2010?

The Microsoft Office 2010 hash format, formally documented in the proprietary **MS-OFFCRYPT** specification, is a legacy cryptographic hash structure designed to secure document-level integrity and authentication within Office files (e.g., `.docx`, `.xlsx`). Introduced alongside Office 2010, this format combines a **SHA-1-based hash** (160-bit) with a **HMAC-SHA1** for message authentication, embedded within the Office Open XML (OOXML) file structure. The structure consists of a **hash block header** (containing version flags and reserved fields), followed by the **SHA-1 hash** of the document’s core XML content, and a **HMAC-SHA1** keyed with a **32-byte symmetric key** (derived from the Office document’s encryption context). This format was primarily used to verify file integrity post-deployment, ensuring tampering could be detected via hash mismatches, though it was not intended for password hashing or secure authentication. The reliance on SHA-1—now cryptographically broken for collision resistance—rendered it obsolete for modern security applications, despite its role in enforcing document integrity checks.

The Microsoft Office 2010 hash format is vulnerable to cracking due to its **inherent cryptographic weaknesses and computational optimizations**. The primary flaw lies in the **use of SHA-1**, which is susceptible to **preimage and collision attacks** (e.g., SHA-1 has been broken for collision attacks with feasible computational effort, as demonstrated by projects like SHA-1 collision attacks in 2017). Additionally, the **lack of salting** in the HMAC-SHA1 key derivation exposes it to **rainbow table attacks** if the symmetric key is reused or predictable. Modern **GPU/ASIC optimizations** (e.g., CUDA-accelerated SHA-1 cracking tools) further exacerbate vulnerabilities by enabling brute-force or birthday-paradox attacks at scale. The **fixed-length hash output (160 bits)** also limits resistance to brute-force, as the key space (2¹⁶⁰) is now trivially reducible via parallelized attacks. Finally, the **document-specific context** of the hash (e.g., tied to OOXML structure) does not mitigate against **adversarial forgery**—an attacker could craft malicious XML payloads that produce valid hashes, bypassing integrity checks.

Identifying Microsoft Office 2010 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 Microsoft Office 2010, security researchers analyze the hash against a strict regular expression (regex) signature (shown above) to find structural matches.

How to Crack Microsoft Office 2010

If you need to recover the plaintext password for a Microsoft Office 2010 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.