Db Wal Recovery

• Use built-in tool commands (e.g., LS, Read) to list directory contents
• Use bash commands (ls -la, find, locate) independently
• Compare outputs—discrepancies are significant clues

Phase 2: File Analysis

When a WAL file is located:

1. Examine file headers:

   • Valid SQLite WAL files start with magic bytes: 377f0682 (hex) or specific WAL header signature
   • Check byte offsets 0-32 for WAL header structure
   • Compare against documented SQLite WAL format (see references/wal_format.md)

2. Analyze binary structure:

   • Use xxd or hexdump for initial inspection
   • Look for recognizable patterns (ASCII strings, repeated structures)
   • Identify frame boundaries in WAL files

3. Detect encryption or corruption:

   • High entropy throughout = likely encrypted
   • Valid header but corrupted frames = partial corruption
   • No recognizable structure = unknown encoding or encryption

Phase 3: Recovery Approaches

Attempt recovery methods in order of likelihood:

For Encrypted Files

1. Search for decryption keys:

   • Environment variables
   • Adjacent files (*.key, *.pem, config files)
   • Database pragmas (PRAGMA key for SQLCipher)

2. Try common encryption schemes:

   • SQLCipher (most common SQLite encryption)
   • SEE (SQLite Encryption Extension)
   • Custom XOR with multi-byte keys (not just single-byte)
   • AES-256-CBC with standard key derivation

3. Test multiple key formats:

   • Raw bytes
   • Hex-encoded strings
   • Base64-encoded keys
   • Passphrase-based derivation (PBKDF2)

For Corrupted Files

1. Attempt SQLite recovery tools:

   • sqlite3 .recover command
   • .dump to extract what's possible
   • Third-party tools like undark or sqlite-recover

2. Manual page reconstruction:

   • Identify valid WAL frames
   • Extract page data from intact frames
   • Apply changes to database manually

3. Partial recovery:

   • Extract readable text strings with strings command
   • Parse individual records from binary data
   • Reconstruct table structure from fragments

For Virtual/Inaccessible Files

When tools show a file that bash cannot access:

1. Investigate the access method:

   • The tool showing the file has special access—understand how
   • Try reading through the same tool that listed the file
   • Look for mount points, FUSE filesystems, or encrypted containers

2. Check for special filesystems:

   • EncFS, gocryptfs, or similar encrypted filesystems
   • FUSE-mounted virtual filesystems
   • Container-based isolation

3. Examine tool capabilities:

   • Some tools may have built-in decryption
   • Check tool documentation for special file handling
   • Try tool-specific read commands

Verification Strategies

Before Declaring Success

1. Verify recovered data makes sense:

   • Check data types match expected schema
   • Validate relationships between records
   • Compare against known valid records

2. Cross-reference with database:

   • Query the main database for gaps or references to missing data
   • Check foreign key relationships
   • Examine indexes for expected entries

3. Test data integrity:

   • Run PRAGMA integrity_check
   • Verify transaction consistency
   • Check checkpoint status

Red Flags Indicating Incorrect Approach

• Finding yourself "guessing" what data should be
• Relying on pattern recognition rather than actual data extraction
• Multiple arbitrary choices for the same record
• High uncertainty about recovered values
• No binary data supporting the recovered values

Common Pitfalls

Pitfall 1: Abandoning Investigation Too Early

Wrong: Conclude file doesn't exist after a few bash commands fail Right: Investigate why built-in tools showed different results; the discrepancy is a clue

Pitfall 2: Single-Method Encryption Testing

Wrong: Try only single-byte XOR and conclude file isn't encrypted Right: Test multiple encryption schemes, key lengths, and formats systematically

Pitfall 3: Pattern-Based Data Generation

Wrong: Notice alphabetical pattern and generate next items in sequence Right: Recovery means extracting actual data; if data cannot be extracted, acknowledge failure

Pitfall 4: Ignoring WAL File Structure

Wrong: Treat WAL as opaque binary blob Right: Parse according to documented SQLite WAL format to identify frames and pages

Pitfall 5: Missing Environmental Clues

Wrong: Focus only on the database files Right: Search entire environment for keys, configuration, related files

Escalation Checklist

If standard recovery fails, verify completion of:

• Compared tool output vs bash output for all file operations
• Searched for encryption keys in environment and adjacent files
• Tested at least 5 different encryption/encoding schemes
• Examined WAL file structure against documented format
• Attempted SQLite built-in recovery commands
• Tried reading through same tool that originally showed the file
• Checked for special filesystems or mount points
• Extracted and analyzed any readable string content
• Documented specific technical blockers preventing recovery

Only after completing this checklist should recovery be considered impossible.

Resources

Reference documentation for detailed technical specifications:

• references/wal_format.md - SQLite WAL file format specification and structure