Recovering Deleted Files with PhotoRec

When to Use

• When recovering deleted files from a forensic disk image or storage device
• When the file system is corrupted, formatted, or overwritten
• During investigations requiring recovery of documents, images, videos, or databases
• When file system metadata is unavailable but raw data sectors remain intact
• For recovering files from memory cards, USB drives, and hard drives

Prerequisites

• PhotoRec installed (part of TestDisk suite)
• Forensic disk image or direct device access (read-only)
• Sufficient output storage space (potentially larger than source)
• Write-blocker if working with original media
• Root/sudo privileges for device access
• Knowledge of target file types for focused recovery

Workflow

Step 1: Install PhotoRec and Prepare the Environment

# Install TestDisk (includes PhotoRec) on Debian/Ubuntu
sudo apt-get install testdisk

# On RHEL/CentOS
sudo yum install testdisk

# On macOS
brew install testdisk

# Verify installation
photorec --version

# Create output directory structure
mkdir -p /cases/case-2024-001/recovered/{all,documents,images,databases}

# Verify the forensic image
file /cases/case-2024-001/images/evidence.dd
ls -lh /cases/case-2024-001/images/evidence.dd

Step 2: Run PhotoRec in Interactive Mode

# Launch PhotoRec against a forensic image
photorec /cases/case-2024-001/images/evidence.dd

# Interactive menu steps:
# 1. Select the disk image: evidence.dd
# 2. Select partition table type: [Intel] for MBR, [EFI GPT] for GPT
# 3. Select partition to scan (or "No partition" for whole disk)
# 4. Select filesystem type: [ext2/ext3/ext4] or [Other] for NTFS/FAT
# 5. Choose scan scope: [Free] (unallocated only) or [Whole] (entire partition)
# 6. Select output directory: /cases/case-2024-001/recovered/all/
# 7. Press C to confirm and begin recovery

# For direct device scanning (with write-blocker)
sudo photorec /dev/sdb

Step 3: Run PhotoRec with Command-Line Options for Targeted Recovery

# Non-interactive mode with specific file types
photorec /d /cases/case-2024-001/recovered/documents/ \
   /cmd /cases/case-2024-001/images/evidence.dd \
   partition_table,options,mode,fileopt,search

# Recover only specific file types using photorec command mode
photorec /d /cases/case-2024-001/recovered/documents/ \
   /cmd /cases/case-2024-001/images/evidence.dd \
   options,keep_corrupted_file,enable \
   fileopt,everything,disable \
   fileopt,doc,enable \
   fileopt,docx,enable \
   fileopt,pdf,enable \
   fileopt,xlsx,enable \
   search

# Recover only image files
photorec /d /cases/case-2024-001/recovered/images/ \
   /cmd /cases/case-2024-001/images/evidence.dd \
   fileopt,everything,disable \
   fileopt,jpg,enable \
   fileopt,png,enable \
   fileopt,gif,enable \
   fileopt,bmp,enable \
   fileopt,tif,enable \
   search

# Recover database files
photorec /d /cases/case-2024-001/recovered/databases/ \
   /cmd /cases/case-2024-001/images/evidence.dd \
   fileopt,everything,disable \
   fileopt,sqlite,enable \
   fileopt,dbf,enable \
   search

Step 4: Organize and Catalog Recovered Files

# PhotoRec outputs files into recup_dir.1, recup_dir.2, etc.
ls /cases/case-2024-001/recovered/all/

# Count recovered files by type
find /cases/case-2024-001/recovered/all/ -type f | \
   sed 's/.*\.//' | sort | uniq -c | sort -rn > /cases/case-2024-001/recovered/file_type_summary.txt

# Sort recovered files into directories by extension
cd /cases/case-2024-001/recovered/all/
for ext in jpg png pdf docx xlsx pptx zip sqlite; do
   mkdir -p /cases/case-2024-001/recovered/sorted/$ext
   find . -name "*.$ext" -exec cp {} /cases/case-2024-001/recovered/sorted/$ext/ \;
done

# Generate SHA-256 hashes for all recovered files
find /cases/case-2024-001/recovered/all/ -type f -exec sha256sum {} \; \
   > /cases/case-2024-001/recovered/recovered_hashes.txt

# Generate file listing with metadata
find /cases/case-2024-001/recovered/all/ -type f \
   -printf "%f\t%s\t%T+\t%p\n" | sort > /cases/case-2024-001/recovered/file_listing.txt

Step 5: Validate and Filter Recovered Files

# Verify file integrity using file signatures
find /cases/case-2024-001/recovered/all/ -type f -exec file {} \; \
   > /cases/case-2024-001/recovered/file_signatures.txt

# Find files with mismatched extension/signature
while IFS= read -r line; do
   filepath=$(echo "$line" | cut -d: -f1)
   filetype=$(echo "$line" | cut -d: -f2-)
   ext="${filepath##*.}"
   if [[ "$ext" == "jpg" ]] && ! echo "$filetype" | grep -qi "JPEG"; then
      echo "MISMATCH: $filepath -> $filetype"
   fi
done < /cases/case-2024-001/recovered/file_signatures.txt > /cases/case-2024-001/recovered/mismatches.txt

# Filter out known-good files using NSRL hash comparison
hashdeep -r -c sha256 /cases/case-2024-001/recovered/all/ | \
   grep -vFf /opt/nsrl/nsrl_sha256.txt > /cases/case-2024-001/recovered/unknown_files.txt

# Remove zero-byte and corrupted files
find /cases/case-2024-001/recovered/all/ -type f -empty -delete
find /cases/case-2024-001/recovered/all/ -name "*.jpg" -exec jpeginfo -c {} \; 2>&1 | \
   grep "ERROR" > /cases/case-2024-001/recovered/corrupted_images.txt

Key Concepts

Concept	Description
File carving	Recovering files from raw data using file header/footer signatures
File signatures	Magic bytes at the start of files identifying their type (e.g., FF D8 FF for JPEG)
Unallocated space	Disk sectors not assigned to any active file; may contain deleted data
Fragmented files	Files stored in non-contiguous sectors; harder to carve completely
Cluster/Block size	Minimum allocation unit on a file system; affects carving granularity
File footer	Byte sequence marking the end of a file (not all formats have footers)
Data remanence	Residual data remaining after deletion until sectors are overwritten
False positives	Carved artifacts that match signatures but contain corrupted or partial data

Tools & Systems

Tool	Purpose
PhotoRec	Open-source file carving tool supporting 300+ file formats
TestDisk	Companion tool for partition recovery and repair
Foremost	Alternative file carver originally developed by US Air Force OSI
Scalpel	High-performance file carver based on Foremost
hashdeep	Recursive hash computation and audit tool
jpeginfo	JPEG file integrity verification
file	Unix utility identifying file types by magic bytes
exiftool	Extract metadata from recovered image and document files

Common Scenarios

Scenario 1: Recovering Deleted Evidence from a Suspect's USB Drive

Image the USB drive with dcfldd, run PhotoRec targeting document and image formats, organize by file type, hash all recovered files, compare against known-bad hash sets, extract metadata from images for GPS and timestamp information.

Scenario 2: Formatted Hard Drive Recovery

Run PhotoRec in "Whole" mode against the entire formatted partition, recover all file types, expect higher false positive rate due to file fragmentation, validate recovered files with signature checking, catalog and hash for evidence chain.

Scenario 3: Memory Card from a Surveillance Camera

Recover deleted video files (AVI, MP4, MOV) from the memory card image, use targeted file type selection to speed recovery, verify video files are playable, extract frame timestamps, document recovery in case notes.

Scenario 4: Corrupted File System on Evidence Drive

When file system metadata is destroyed, PhotoRec bypasses the file system entirely and carves from raw sectors, recover maximum possible data, accept that file names and directory structure will be lost, rename files based on content during review.

Output Format

PhotoRec Recovery Summary:
  Source Image:     evidence.dd (500 GB)
  Partition:        NTFS (Partition 2)
  Scan Mode:        Free space only

  Files Recovered:  4,523
    Documents:      234 (doc: 45, docx: 89, pdf: 67, xlsx: 33)
    Images:         2,145 (jpg: 1,890, png: 198, gif: 57)
    Videos:         34 (mp4: 22, avi: 12)
    Archives:       67 (zip: 45, rar: 22)
    Databases:      12 (sqlite: 8, dbf: 4)
    Other:          2,031

  Data Recovered:   12.4 GB
  Corrupted Files:  312 (flagged for review)
  Output Directory: /cases/case-2024-001/recovered/all/
  Hash Manifest:    /cases/case-2024-001/recovered/recovered_hashes.txt

Verification Criteria

Confirm successful execution by validating:

• [ ] All prerequisite tools and access requirements are satisfied
• [ ] Each workflow step completed without errors
• [ ] Output matches expected format and contains expected data
• [ ] No security warnings or misconfigurations detected
• [ ] Results are documented and evidence is preserved for audit

Compliance Framework Mapping

This skill supports compliance evidence collection across multiple frameworks:

• SOC 2: CC7.3 (Incident Identification), CC7.4 (Incident Response)
• ISO 27001: A.16.1 (Security Incident Management), A.12.4 (Logging)
• NIST 800-53: AU-6 (Audit Review), IR-4 (Incident Handling), AU-9 (Audit Protection)
• NIST CSF: RS.AN (Analysis), RS.RP (Response Planning)

Claw GRC Tip: When this skill is executed by a registered agent, compliance evidence is automatically captured and mapped to the relevant controls in your active frameworks.

Deploying This Skill with Claw GRC

Agent Execution

Register this skill with your Claw GRC agent for automated execution:

# Install via CLI
npx claw-grc skills add recovering-deleted-files-with-photorec

# Or load dynamically via MCP
grc.load_skill("recovering-deleted-files-with-photorec")

Audit Trail Integration

When executed through Claw GRC, every step of this skill generates tamper-evident audit records:

• SHA-256 chain hashing ensures no step can be modified after execution
• Evidence artifacts (configs, scan results, logs) are automatically attached to relevant controls
• Trust score impact — successful execution increases your agent's trust score

Continuous Compliance

Schedule this skill for recurring execution to maintain continuous compliance posture. Claw GRC monitors for drift and alerts when re-execution is needed.