The Sleuth Kit (TSK) is a powerful collection of command-line tools for digital forensic analysis. It examines disk images and file systems at multiple layers—from raw disk blocks to individual files—supporting NTFS, FAT, EXT2/3/4, HFS+, and more. TSK forms the engine behind the Autopsy GUI forensic browser.
Installation
Linux (Debian/Ubuntu)
sudo apt-get install sleuthkit
sudo apt-get install autopsy # Optional GUI frontend
macOS
brew install sleuthkit
brew install autopsy
Windows
Download installer from sleuthkit.org or compile from source.
From Source
git clone https://github.com/sleuthkit/sleuthkit.git
cd sleuthkit
./configure
make
sudo make install
Image and File System Analysis
List Partitions and Volume Offsets
mmls -t partition_type image.dd
mmls image.dd # Auto-detect type
mmls -i raw image.dd # Specify raw image type
| Command | Description |
|---|
mmls image.dd | List partitions/volumes in disk image |
mmls -t dos image.dd | List DOS/MBR partitions |
mmls -t gpt image.dd | List GUID Partition Table entries |
mmls -B image.dd | Show sector offsets for partition analysis |
File System Statistics
fsstat image.dd
fsstat -o offset image.dd # Analyze specific partition
fsstat -i fat image.dd # Specify file system type
| Command | Description |
|---|
fsstat image.dd | Display file system metadata and statistics |
fsstat -o 2048 image.dd | Analyze partition at 2048 sector offset |
fsstat -i ext2 image.dd | Manually specify EXT2 file system |
fsstat -i ntfs image.dd | Analyze NTFS file system details |
File System Layer Analysis
List Files and Directories
fls image.dd
fls -r image.dd # Recursive listing
fls -o offset image.dd # Specify partition offset
fls -m image.dd # Mactime format (timestamps)
fls -u image.dd # Include unallocated entries
fls -H image.dd # Include deleted entries (with hash)
| Command | Description |
|---|
fls image.dd | List directory contents of root |
fls -r image.dd | Recursively list all files |
fls -o 2048 image.dd | List files from partition at offset 2048 |
fls -u image.dd | Show unallocated (deleted) directory entries |
fls -m image.dd > timeline.txt | Output in mactime format for timeline |
fls -F image.dd | Fast mode (fewer details, faster processing) |
icat image.dd inode_number > recovered_file
icat -o offset image.dd inode_number > file_output
| Command | Description |
|---|
icat image.dd 50 > file.txt | Extract inode 50 content to file |
icat -o 2048 image.dd 50 > file.txt | Extract from specific partition offset |
icat -r image.dd 50 > file.dat | Raw extraction without interpretation |
Find Files by Name
ffind image.dd filename
ffind -i image.dd filename # Case-insensitive
ffind -o offset image.dd filename # Partition offset
| Command | Description |
|---|
ffind image.dd secret.txt | Find file by name |
ffind -i image.dd secret.txt | Case-insensitive file search |
ffind image.dd "*temp*" | Wildcard file name search |
ffind -o 2048 image.dd *.jpg | Find JPEGs in specific partition |
Inode Statistics
istat image.dd inode_number
istat -o offset image.dd inode_number
| Command | Description |
|---|
istat image.dd 100 | Display inode 100 metadata (times, size, blocks) |
istat -o 2048 image.dd 100 | Inode details from partition at offset |
istat -z timezone image.dd 100 | Display times in specific timezone |
List Inodes
ils image.dd
ils -o offset image.dd # Partition offset
ils -a image.dd # All inodes (deleted too)
ils -m image.dd # Mactime format
| Command | Description |
|---|
ils image.dd | List allocated inodes |
ils -a image.dd | List all inodes (allocated and deleted) |
ils -m image.dd | Output in mactime timeline format |
ils -o 2048 image.dd | List inodes from partition |
Data Layer Analysis
Block Statistics
blkstat image.dd block_number
blkstat -o offset image.dd block_number
| Command | Description |
|---|
blkstat image.dd 5000 | Display block 5000 information |
blkstat -o 2048 image.dd 5000 | Block analysis from partition |
blkcat image.dd block_number > block_output
blkcat -o offset image.dd 1000-1010 > blocks.bin # Range of blocks
| Command | Description |
|---|
blkcat image.dd 5000 > block.bin | Extract block 5000 raw data |
blkcat image.dd 5000-5010 > blocks.bin | Extract range of blocks |
blkcat -o 2048 image.dd 5000 > block.bin | Extract from partition |
Block Listing
blkls image.dd
blkls -a image.dd # All blocks (allocated and unallocated)
blkls -u image.dd # Only unallocated blocks
| Command | Description |
|---|
blkls image.dd | List allocated blocks |
blkls -a image.dd | List all blocks |
blkls -u image.dd | List unallocated (free) blocks |
Timeline Creation and Analysis
fls -r -m image.dd > body_file.txt
ils -m image.dd >> body_file.txt
mactime -b body_file.txt -y > timeline.txt
| Command | Description |
|---|
fls -r -m image.dd > body.txt | Generate body file from file system |
mactime -b body.txt > timeline.txt | Create sorted timeline |
mactime -b body.txt -y > csv_timeline.csv | Output timeline in CSV format |
mactime -b body.txt -d > detailed.txt | Detailed timeline output |
Combine Multiple Timelines
fls -r -m /mnt/image1.dd > image1_body.txt
fls -r -m /mnt/image2.dd > image2_body.txt
cat image1_body.txt image2_body.txt | mactime > combined_timeline.txt
Keyword and String Searching
Search for Strings in Image
srch_strings image.dd | grep -i password
| Command | Description |
|---|
srch_strings image.dd | Extract strings from image |
srch_strings image.dd | grep password | Find password-related strings |
srch_strings -t d image.dd | grep -i email | Search for email addresses |
srch_strings image.dd | sort | uniq > strings_found.txt
strings image.dd | grep -E "http|ftp|smtp" > urls_found.txt
Hash Databases
Create Hash Database
md5sum -r mounted_filesystem > filesystem_hashes.txt
hfind -i md5 filesystem_hashes.txt hash_value # Later lookup
Use NIST NSRL Hash Database
# Download and import NSRL database
hfind -i md5 nsrl.txt hash_to_search
| Command | Description |
|---|
hfind -i md5 db.txt hash_value | Look up hash in database |
hfind -i sha1 hashes.txt known_hash | Find matching SHA1 |
hfind -o db.txt hash_file | Search multiple hashes from file |
Common Forensic Workflows
Quick Disk Image Analysis
# 1. Identify partitions
mmls evidence.dd
# 2. Analyze file system
fsstat -o 2048 evidence.dd
# 3. List files
fls -r -o 2048 evidence.dd > files.txt
# 4. Create timeline
fls -r -m -o 2048 evidence.dd > body.txt
mactime -b body.txt > timeline.csv
Find Deleted Files
# 1. List all inodes (including deleted)
ils -a -o 2048 image.dd > all_inodes.txt
# 2. List deleted directory entries
fls -u -o 2048 image.dd > deleted_entries.txt
# 3. Check specific inode
istat -o 2048 image.dd 12345
# 4. Recover file
icat -o 2048 image.dd 12345 > recovered_file
Locate Suspicious Files
# Find files modified during specific date range
fls -r -m image.dd | awk -F'|' '$4 >= 1234567890 && $4 <= 1234577890'
# Search for executables
fls -r image.dd | grep -E "\.(exe|elf|so)$"
# Find recently accessed files
ils -a image.dd | sort -t'|' -k6 -r | head -20
Recover Partition After Accidental Deletion
# 1. Scan for lost partitions
mmls image.dd
# 2. If partition table corrupted, try recovery
fsstat image.dd # May show lost file systems
# 3. Search for file system signatures
srch_strings image.dd | grep -E "NTFS|EXT[234]|HFS"
# 4. Use photorec for carving (if TSK recovery insufficient)
photorec /d /mnt/recovered image.dd
Autopsy Integration
Launch Autopsy GUI
autopsy
# Opens web interface (usually http://localhost:9999)
Add Evidence to Autopsy
- Open Autopsy web interface
- Create new case
- Add host/device
- Add data source (disk image)
- Configure ingest modules (hash lookup, keyword search, timeline)
- View results in analysis interface
Command-Line Evidence Processing
# Autopsy can process images via CLI in some versions
autopsy -c case_name -a image.dd
File System Types
| File System | Tools | Notes |
|---|
| NTFS | All TSK tools | Windows primary, fully supported |
| FAT12/16/32 | All TSK tools | Older Windows/USB, well supported |
| EXT2/3/4 | All TSK tools | Linux primary, fully supported |
| HFS+ | All TSK tools | macOS, fully supported |
| UFS | All TSK tools | BSD/Solaris, supported |
| ISO 9660 | All TSK tools | CD/DVD, supported |
Tips and Tricks
Batch Processing Multiple Images
for image in *.dd; do
echo "Processing $image"
fls -r -m "$image" > "${image%.dd}_body.txt"
done
Create Forensic Copy
# Using dd (creates exact copy)
dd if=/dev/sda of=disk_image.dd status=progress
# Using dcfldd (better error handling)
dcfldd if=/dev/sda of=disk_image.dd hash=md5 progress=on
Mount Image Read-Only for Inspection
# Linux with offset
sudo mount -o ro,loop,offset=$((2048 * 512)) image.dd /mnt/evidence
# macOS
hdiutil attach -nomount image.dd
mount_msdos -r /dev/disk2s1 /mnt/evidence
fls -r -m image.dd | mactime -b - | sort > timeline.csv
# Import into Timesketch, Analyst's Notebook, or Excel
| Technique | Benefit |
|---|
-F flag on fls | Faster processing, fewer details |
| Parallel processing | Process multiple images simultaneously |
Partition offset (-o) | Faster when you know exact partition location |
-u flag selectively | Only search unallocated when needed |
Common Issues
| Problem | Solution |
|---|
| File system not recognized | Use -i to manually specify type |
| Wrong inode number | Verify with ffind before extraction |
| Timeline gaps | Combine fls and ils output |
| Memory issues on large images | Process partitions separately |
| Bad sector errors | Use dcfldd for acquisition with error handling |
Additional Resources
