Fast Recovery Techniques¶

Practical methods to recover access to password-protected Office documents without cracking the password hash. Every technique here exploits a structural weakness in how Office stores protection: default passwords, cleartext storage, reversible obfuscation, strippable verifiers, or trivially collidable checksums. None require a GPU, a wordlist, or hashcat.

The Key Insight¶

Most Office "passwords" do not encrypt content. The product × gate matrix in analysis/overview.md shows that of the ~40 distinct protection gates across all Office formats, only a handful (the 🔴 gates) actually encrypt document bytes with a password-derived key. Everything else falls into one of these categories:

Category	What it means	Recovery time
🟢 Cleartext / Decode	The password is stored in the file, either literally or under trivially reversible obfuscation. Read it out.	Instant
🟡 Verifier only	The document body is plaintext. A hash or checksum of the password is stored in the file and can be deleted or zeroed without touching the content.	Seconds (hex/XML edit)
⚪ Advisory / UI-only	The "protection" is a flag that controls application behavior, not data access. Flip the flag or use a different tool.	Instant

Even some 🔴 gates fall to fast recovery because the file was encrypted under a known default password that Office applies automatically, or because the "encryption" is XOR obfuscation with a key derivable from the file itself.

Decision Tree¶

Given a protected file, walk this tree top to bottom. The first technique that applies gives you instant or near-instant recovery. Only fall through to hashcat if every fast path fails.

flowchart TD
  START(["Protected\nOffice file"]) --> DEFAULT{"Known default\npassword?"}

  DEFAULT -->|"Excel encrypted\nwith no user password"| VS["Try VelvetSweatshop\n→ defaults.md"]
  DEFAULT -->|"PPT 2003-2007 SP1\nencrypted .ppt"| HR["Try /01Hannes Ruescher/01\n→ defaults.md"]
  DEFAULT -->|"No / didn't work"| READ

  VS --> DONE(["🟢 Recovered"])
  HR --> DONE

  READ{"Password stored\nin the file?"}
  READ -->|".doc modify\n.ppt modify"| CLEAR["Read cleartext password\n→ cleartext.md"]
  READ -->|"VBA DPB plaintext case\n(VBA 5.0 / MAY<6>)"| CLEAR
  READ -->|"PST password field"| CLEAR_PST["Read CRC-32 value\n(advisory only, data\nnot encrypted)\n→ cleartext.md"]
  READ -->|"No"| DECODE

  CLEAR --> DONE
  CLEAR_PST --> DONE

  DECODE{"Reversible\nobfuscation?"}
  DECODE -->|"XOR obfuscation\n.doc / .xls"| XOR_DEC["Derive XOR array\nfrom verifier, decode\n→ decode.md"]
  DECODE -->|"Access .mdb\nJet 3/4"| JET_DEC["XOR with fixed/date key\n→ decode.md"]
  DECODE -->|"PST body cipher"| PST_DEC["CryptPermute / CryptCyclic\nkeyless decode\n→ decode.md"]
  DECODE -->|"VBA DPB wrapper"| VBA_DEC["Self-chaining XOR decrypt\n→ decode.md"]
  DECODE -->|"No"| STRIP

  XOR_DEC --> DONE
  JET_DEC --> DONE
  PST_DEC --> DONE
  VBA_DEC --> DONE

  STRIP{"Strippable\nverifier?"}
  STRIP -->|"OOXML protection\n(sheet, workbook,\ndocument, modify,\nrevision, edit range)"| XML_STRIP["Delete protection element\nfrom ZIP XML\n→ strip.md"]
  STRIP -->|"Binary .xls/.doc\nprotection records"| BIN_STRIP["Zero or remove\nprotection record/field\n→ strip.md"]
  STRIP -->|"ODF table:protected\ntext:protected"| ODF_STRIP["Remove protected\nattribute from XML\n→ strip.md"]
  STRIP -->|"VBA CMG/DPB/GC"| VBA_STRIP["Replace protection lines\nwith no-password values\n→ strip.md"]
  STRIP -->|"No"| COLLIDE

  XML_STRIP --> DONE
  BIN_STRIP --> DONE
  ODF_STRIP --> DONE
  VBA_STRIP --> DONE

  COLLIDE{"Trivially\ncollidable?"}
  COLLIDE -->|"16-bit verifier\n(.xls sheet/book/write)"| COL16["Instant 16-bit collision\n→ collide.md"]
  COLLIDE -->|"32-bit verifier\n(.doc XOR lKey)"| COL32["Fast 32-bit collision\n→ collide.md"]
  COLLIDE -->|"PST CRC-32"| COL_CRC["CRC-32 collision\n→ collide.md"]
  COLLIDE -->|"No"| HASHCAT

  COL16 --> DONE
  COL32 --> DONE
  COL_CRC --> DONE

  HASHCAT(["🔴 Real encryption\nFall through to\nhash extraction +\nhashcat / JtR"])

  style DONE fill:#2d8,stroke:#1a6,color:#000
  style HASHCAT fill:#d44,stroke:#a22,color:#fff
  style START fill:#68f,stroke:#46d,color:#fff

Technique Summary¶

Which technique works on which gate. Check marks indicate the technique applies; the badge shows recovery speed.

Gate	Format	Default	Cleartext	Decode	Strip	Collide	Bypass
Open (XOR obfuscation)	`.doc`	—	—	🟢	—	🟢	—
Open (XOR obfuscation)	`.xls`	—	—	🟢	—	🟢	—
Open (VelvetSweatshop)	`.xls`/`.xlsx`	🟢	—	—	—	—	—
Open (/01Hannes Ruescher/01)	`.ppt`	🟢	—	—	—	—	—
Modify / Write Reservation	`.doc`	—	🟢	—	🟢	—	—
Modify / Write Reservation	`.ppt`	—	🟢	—	🟢	—	—
Modify / Write Reservation	`.xls`	—	—	—	🟢	🟢	—
Modify / Write Reservation	`.docx`	—	—	—	🟢	—	—
Modify / Write Reservation	`.xlsx`	—	—	—	🟢	—	—
Modify / Write Reservation	`.pptx`	—	—	—	🟢	—	—
Sheet Protection	`.xls`	—	—	—	🟢	🟢	—
Sheet Protection	`.xlsx`/`.xlsb`	—	—	—	🟢	—	—
Workbook Protection	`.xls`	—	—	—	🟢	🟢	—
Workbook Protection	`.xlsx`/`.xlsb`	—	—	—	🟢	—	—
Document Protection	`.doc`	—	—	—	🟢	🟢	—
Document Protection	`.docx`	—	—	—	🟢	—	—
Edit Ranges	`.xls`	—	—	—	🟢	🟢	—
Edit Ranges	`.xlsx`/`.xlsb`	—	—	—	🟢	—	—
Revision Protection	`.xls`	—	—	—	🟢	🟢	—
VBA Project Lock	all	—	🟡	🟢	🟢	—	🟢
PST Password	`.pst`	—	🟢	—	🟢	🟢	—
PST Body Cipher	`.pst`	—	—	🟢	—	—	—
Access Open	`.mdb` (Jet 3)	—	—	🟢	—	—	—
Access Open	`.mdb` (Jet 4)	—	—	🟢	—	—	—
ODF Sheet/Cell Protection	`.odt`/`.ods`	—	—	—	🟢	—	—

Badge legend: 🟢 = instant (< 1 second) | 🟡 = fast (seconds, may need code page detection) | 🔴 = not applicable (fall through to hashcat)

Technique Documents¶

#	Technique	File	What it does
1	Default Passwords	defaults.md	Try known default passwords that Office applies automatically: `VelvetSweatshop` for Excel, `/01Hannes Ruescher/01` for PowerPoint. Spec-confirmed in [MS-OFFCRYPTO] SS2.4.2.3, product behavior notes <25> and <26>.
2	Cleartext Passwords	cleartext.md	Read passwords stored in the clear: `.doc` write-reservation in `SttbfAssoc` index 0x11 (UTF-16LE), `.ppt` modify password in `ModifyPasswordAtom` (UTF-16LE), VBA plaintext case under the DPB wrapper, PST CRC-32 advisory value.
3	Reversible Decode	decode.md	Reverse trivial obfuscation: XOR obfuscation arrays for `.doc`/`.xls` (16-byte repeating key derived from in-file verifier), Jet fixed-key and date-key XOR for `.mdb`, PST permutative/cyclic body ciphers (keyless table lookup), VBA DPB self-chaining XOR wrapper.
4	Strip Protection	strip.md	Delete or zero protection elements from files where the document body is plaintext. OOXML: unzip, remove XML attributes/elements (`sheetProtection`, `workbookProtection`, `documentProtection`, `writeProtection`, `modifyVerifier`, `protectedRange`, `fileSharing`), rezip. OLE binary: zero verifier fields in BIFF records or DopBase. ODF: remove `table:protected` / `text:protected` attributes. VBA: replace `CMG=`/`DPB=`/`GC=` with no-password sentinel values.
5	Instant Collision	collide.md	Find a colliding password for trivially small verifier spaces. 16-bit `CreatePasswordVerifier_Method1` (2^16 = 65,536 buckets, instant exhaustive search): covers `.xls` sheet/workbook/write/revision protection and edit ranges. 32-bit XOR verifier (`.doc` `FibBase.lKey`): fast collision from the combined XorKey+Verifier16 space. PST CRC-32 (2^32 buckets): standard CRC-32 collision or preimage in milliseconds.
6	VBA Bypass	bypass.md	Access VBA macro source code despite "Lock project for viewing": the password gates only the VBE UI, not the data. Module streams are compressed ([MS-OVBA] SS2.4.1) but never encrypted. Decompress directly with `olefile` + `zlib`, or patch the `CMG=`/`DPB=`/`GC=` lines to unlock the editor. Content integrity hashes ([MS-OVBA] SS2.4.2) deliberately exclude the protection fields, so modifications do not invalidate them.

Cross-References¶

Resource	Path	What it covers
Gate overview + detection tree	analysis/overview.md	Full product x gate matrix, algorithm x product matrix, file detection decision tree
XOR obfuscation spec	analysis/algorithms/password/xor-obfuscation.md	Method 1/2 KDF, XorMatrix, PadArray, data transformation, default passwords
VBA project password spec	analysis/algorithms/password/vba-project-password.md	DPB wrapper, password hash structure, content integrity hashes
ISO protection hash spec	analysis/algorithms/password/iso-protection-hash.md	OOXML sheet/workbook/document/write protection KDF
PST CRC-32 spec	analysis/algorithms/password/pst-crc32.md	Advisory password gate, CRC-32 parameters
PST body cipher spec	analysis/algorithms/non-password/pst-body-cipher.md	Permutative and cyclic keyless decode
Access Jet obfuscation	analysis/algorithms/non-password/access-jet-obfuscation.md	Fixed-key and date-key XOR for `.mdb`
Word format reference	analysis/formats/word.md	`.doc`/`.docx` gate locations, container structure
Excel format reference	analysis/formats/excel.md	`.xls`/`.xlsx` gate locations, VelvetSweatshop details
PowerPoint format reference	analysis/formats/powerpoint.md	`.ppt`/`.pptx` gate locations, `/01Hannes Ruescher/01` details
Outlook format reference	analysis/formats/outlook.md	`.pst` password and body cipher locations
Access format reference	analysis/formats/access.md	`.mdb`/`.accdb` Jet/ACE header layout

What These Techniques Do NOT Cover¶

These techniques work only against gates where the protection mechanism has a structural shortcut. They do not help with:

🔴 ECMA-376 Agile encryption (.docx/.xlsx/.pptx with SHA-512 + AES-256, 100,000 iterations) — real encryption, requires password recovery via hashcat mode 9600
🔴 ECMA-376 Standard encryption (AES + SHA-1, 50,000 iterations) — real encryption, hashcat mode 9500
🔴 RC4 CryptoAPI + SHA-1 (.doc/.xls/.ppt with non-default passwords) — real encryption, hashcat mode 9800/9700/9800
🔴 RC4 + MD5 legacy 40-bit (.doc/.xls older than Office 2003) — real encryption, hashcat mode 9700/9800
🔴 ACE 2010+ encryption (.accdb with SHA-512 + AES-256) — real encryption, analogous to agile
🔴 ODF encryption (PBKDF2/Argon2id + AES-256 or Blowfish) — real encryption, hashcat modes 18400/18600
🔴 OneNote encryption — uses the same ECMA-376 Standard/Agile schemes
⚪ IRM / RMS — certificate-based, no password to recover
⚪ Digital signatures — PKI integrity, not access control

For these, extract the hash with the appropriate tool and proceed to password recovery. See hashcat current modes and proposed unified design for extraction procedures and hashcat module mappings.