ctf

name	CTF•数字取证
description	用于磁盘镜像、内存转储、事件日志、PCAP、隐写分析、Windows 注册表、音频信号、Docker 镜像、coredump 以及已删除文件与凭据恢复等取证类 CTF 题;触发名:ctf-forensics
license	MIT
compatibility	Requires filesystem-based agent (Claude Code or similar) with bash, Python 3, and internet access for tool installation.
allowed-tools	Bash Read Write Edit Glob Grep Task WebFetch WebSearch
metadata	{"user-invocable":"false"}

CTF Forensics & Blockchain

Quick reference for forensics CTF challenges. Each technique has a one-liner here; see supporting files for full details.

Prerequisites

Python packages (all platforms):

pip install volatility3 Pillow numpy matplotlib

Linux (apt):

apt install binwalk foremost libimage-exiftool-perl tshark sleuthkit \
  ffmpeg steghide testdisk john pcapfix

macOS (Homebrew):

brew install binwalk exiftool wireshark sleuthkit ffmpeg \
  testdisk john-jumbo

Ruby gems (all platforms):

gem install zsteg

Additional Resources

• 3d-printing.md - 3D printing forensics (PrusaSlicer binary G-code, QOIF, heatshrink)
• windows.md - Windows forensics (registry, SAM, event logs, recycle bin, NTFS alternate data streams, USN journal, PowerShell history, Defender MPLog, WMI persistence, Amcache)
• network.md - Network forensics basics (tcpdump, TLS/SSL keylog decryption, TLS master key extraction from coredump, Wireshark, PCAP, port scanning, SMB3 decryption, 5G/NR protocols, WordPress recon, credentials, USB HID steno, BCD encoding, HTTP file upload exfiltration, split archive reassembly via timestamp ordering)
• network-advanced.md - Advanced network forensics (packet interval timing encoding, NTLMv2 hash cracking, TCP flag covert channel, DNS last-byte steganography, DNS trailing byte binary encoding, multi-layer PCAP with XOR + ZIP and mDNS key, Brotli decompression bomb seam analysis, SMB RID recycling via LSARPC, Timeroasting MS-SNTP hash extraction, dnscat2 reassembly, RADIUS shared secret cracking, RC4 stream identification, ICMP payload byte rotation, ICMP ping time-delay covert channel)
• peripheral-capture.md - USB/HID/Bluetooth peripheral traffic reconstruction (USB HID mouse/pen drawing recovery, USB HID keyboard capture decoding, USB keyboard LED Morse code exfiltration, USB HID keyboard arrow key navigation tracking, Bluetooth RFCOMM packet reassembly)
• disk-and-memory.md - Core disk/memory forensics (Volatility, disk mounting/carving, VM/OVA/VMDK, VMware snapshots, GIMP raw memory dump visual inspection, coredumps, Windows KAPE triage, PowerShell ransomware, Android forensics, Docker container forensics, cloud storage forensics, BSON reconstruction, TrueCrypt/VeraCrypt mounting)
• disk-advanced.md - Advanced disk and memory techniques (deleted partitions, ZFS forensics, GPT GUID encoding, VMDK sparse parsing, memory dump string carving, ransomware key recovery, WordPerfect macro XOR, minidump ISO 9660 recovery, APFS snapshot recovery, RAID 5 XOR recovery, HFS+ resource fork recovery, Kyoto Cabinet hash DB forensics, SQLite edit history reconstruction)
• disk-recovery.md - Disk recovery and extraction patterns (LUKS master key recovery, PRNG timestamp seed brute-force, VBA macro binary recovery, FemtoZip decompression, XFS filesystem reconstruction, tar duplicate entry extraction, nested matryoshka filesystem extraction, anti-carving via null byte interleaving, BTRFS subvolume/snapshot recovery, FAT16 free space data recovery, FAT16 deleted file recovery via Sleuth Kit fls/icat, ext2 orphaned inode recovery via fsck, corrupted ZIP header repair)

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When to Pivot

• If you recover an encrypted blob and the hard part becomes RSA, AES, or lattice work, switch to /ctf-crypto.
• If the evidence really points to malware staging, beacon config extraction, or packed samples, switch to /ctf-malware.
• If the artifact is a web app backup or API dump and the remaining problem is application logic, switch to /ctf-web.
• If the forensic evidence is really an encoding puzzle, steganography trick, or esoteric format rather than true forensics, switch to /ctf-misc.
• If you need to trace infrastructure, attribute actors, or investigate public records from forensic findings, switch to /ctf-osint.
• If the recovered artifact is a compiled binary or firmware that needs disassembly and analysis, switch to /ctf-reverse.

Quick Start Commands

# File analysis
file suspicious_file
exiftool suspicious_file     # Metadata
binwalk suspicious_file      # Embedded files
strings -n 8 suspicious_file
hexdump -C suspicious_file | head  # Check magic bytes

# Disk forensics
sudo mount -o loop,ro image.dd /mnt/evidence
fls -r image.dd              # List files
photorec image.dd            # Carve deleted files

# Memory forensics (Volatility 3)
vol3 -f memory.dmp windows.info
vol3 -f memory.dmp windows.pslist
vol3 -f memory.dmp windows.filescan

See disk-and-memory.md for full Volatility plugin reference, VM forensics, and coredump analysis.

Log Analysis

grep -iE "(flag|part|piece|fragment)" server.log     # Flag fragments
grep "FLAGPART" server.log | sed 's/.*FLAGPART: //' | uniq | tr -d '\n'  # Reconstruct
sort logfile.log | uniq -c | sort -rn | head         # Find anomalies

See linux-forensics.md for Linux attack chain analysis and Docker image forensics.

Windows Event Logs (.evtx)

Key Event IDs:

• 1001 - Bugcheck/reboot
• 1102 - Audit log cleared
• 4720 - User account created
• 4781 - Account renamed

RDP Session IDs (TerminalServices-LocalSessionManager):

• 21 - Session logon succeeded
• 24 - Session disconnected
• 1149 - RDP auth succeeded (RemoteConnectionManager, has source IP)

import Evtx.Evtx as evtx
with evtx.Evtx("Security.evtx") as log:
    for record in log.records():
        print(record.xml())

See windows.md for full event ID tables, registry analysis, SAM parsing, USN journal, and anti-forensics detection.

• NTFS Alternate Data Streams (ADS): Hidden data attached to files via named NTFS streams. Invisible to dir/Explorer. Detect with fls -r image.dd | grep ":", extract with icat. See windows.md.

When Logs Are Cleared

If attacker cleared event logs, use these alternative sources:

1. USN Journal ($J) - File operations timeline (MFT ref, timestamps, reasons)
2. SAM registry - Account creation from key last_modified timestamps
3. PowerShell history - ConsoleHost_history.txt (USN DATA_EXTEND = command timing)
4. Defender MPLog - Separate log with threat detections and ASR events
5. Prefetch - Program execution evidence
6. User profile creation - First login time (profile dir in USN journal)

See windows.md for detailed parsing code and anti-forensics detection checklist.

Steganography

steghide extract -sf image.jpg
zsteg image.png              # PNG/BMP analysis
stegsolve                    # Visual analysis

• Binary border stego: Black/white pixels in 1px image border encode bits clockwise

• FFT frequency domain: Image data hidden in 2D FFT magnitude spectrum; try np.fft.fft2 visualization

• DTMF audio: Phone tones encoding data; decode with multimon-ng -a DTMF

• Multi-layer PDF: Check hidden comments, post-EOF data, XOR with keywords, ROT18 final layer

• SSTV + LSB: SSTV signal may be red herring; check 2-bit LSB of audio samples with stegolsb

• SVG keyframes: Animation keyTimes/values attributes encode binary/Morse via fill color alternation

• PNG chunk reorder: Fix chunk order: IHDR → ancillary → IDAT (in order) → IEND

• File overlays: Check after IEND for appended archives with overwritten magic bytes

• APNG frame extraction: Animated PNG has multiple frames; extract with apngdis or parse fdAT/fcTL chunks. See steganography.md.

• PNG height/CRC manipulation: Modify IHDR height field, brute-force until CRC matches to reveal hidden rows. See steganography.md.

• Pixel coordinate chain stego: Linked-list traversal where R=data byte, G/B=next pixel coordinates. See stego-image.md.

• AVI frame differential: XOR consecutive video frames to reveal hidden data in pixel differences. See stego-image.md.

• Custom freq DTMF: Non-standard dual-tone frequencies; generate spectrogram first (ffmpeg -i audio -lavfi showspectrumpic), map custom grid to keypad digits, decode variable-length ASCII

See steganography.md, stego-advanced.md, and stego-advanced-2.md for full code examples and decoding workflows.

PDF Analysis

exiftool document.pdf        # Metadata (often hides flags!)
pdftotext document.pdf -     # Extract text
strings document.pdf | grep -i flag
binwalk document.pdf         # Embedded files

Advanced PDF stego (Nullcon 2026 rdctd): Six techniques -- invisible text separators, URI annotations with escaped braces, Wiener deconvolution on blurred images, vector rectangle QR codes, compressed object streams (mutool clean -d), document metadata fields.

See steganography.md for full PDF steganography techniques and code.

Disk / VM / Memory Forensics

# Disk images
sudo mount -o loop,ro image.dd /mnt/evidence
fls -r image.dd && photorec image.dd

# VM images (OVA/VMDK)
tar -xvf machine.ova
7z x disk.vmdk -oextracted "Windows/System32/config/SAM" -r

# Memory (Volatility 3)
vol3 -f memory.dmp windows.pslist
vol3 -f memory.dmp windows.cmdline
vol3 -f memory.dmp windows.netscan
vol3 -f memory.dmp windows.dumpfiles --physaddr <addr>

# String carving
strings -a -n 6 memdump.bin | grep -E "FLAG|SSH_CLIENT|SESSION_KEY"

# Coredump
gdb -c core.dump  # info registers, x/100x $rsp, find "flag"

See disk-and-memory.md for full Volatility plugin reference, VM forensics, and VMware snapshots. See disk-advanced.md for deleted partition recovery, ZFS forensics, and ransomware analysis.

Windows Password Hashes

# Extract with impacket, crack with hashcat -m 1000
python -c "from impacket.examples.secretsdump import *; SAMHashes('SAM', LocalOperations('SYSTEM').getBootKey()).dump()"

See windows.md for SAM details and network-advanced.md for NTLMv2 cracking from PCAP.

Bitcoin Tracing

• Use mempool.space API: https://mempool.space/api/tx/<TXID>
• Peel chain: ALWAYS follow LARGER output; round amounts indicate peels

Uncommon File Magic Bytes

Magic	Format	Extension	Notes
OggS	Ogg container	.ogg	Audio/video
RIFF	RIFF container	.wav,.avi	Check subformat
%PDF	PDF	.pdf	Check metadata & embedded objects
GCDE	PrusaSlicer binary G-code	.g, .bgcode	See 3d-printing.md

Common Flag Locations

• PDF metadata fields (Author, Title, Keywords)
• Image EXIF data
• Deleted files (Recycle Bin $R files)
• Registry values
• Browser history
• Log file fragments
• Memory strings

WMI Persistence Analysis

Pattern (Backchimney): Malware uses WMI event subscriptions for persistence (MITRE T1546.003).

python PyWMIPersistenceFinder.py OBJECTS.DATA

• Look for FilterToConsumerBindings with CommandLineEventConsumer
• Base64-encoded PowerShell in consumer commands
• Event filters triggered on system events (logon, timer)

See windows.md for WMI repository analysis details.

Network Forensics Quick Reference

• TFTP netascii: Binary transfers corrupted; fix with data.replace(b'\r\n', b'\n').replace(b'\r\x00', b'\r')
• TLS keylog decryption: Import SSLKEYLOGFILE or RSA private key into Wireshark (Edit → Preferences → Protocols → TLS)
• TLS weak RSA: Extract cert, factor modulus, generate private key with rsatool, add to Wireshark
• USB audio: Extract isochronous data with tshark -e usb.iso.data, import as raw PCM in Audacity
• NTLMv2 from PCAP: Extract server challenge + NTProofStr + blob from NTLMSSP_AUTH, brute-force
• WPA/WEP WiFi decryption: aircrack-ng -w wordlist capture.pcap cracks WPA handshake; WEP cracked with enough IVs. See network.md.
• PCAP repair: pcapfix -d corrupted.pcap repairs broken PCAP headers/checksums for Wireshark loading. See network.md.
• USB HID keyboard decoding: Extract 8-byte HID reports from USB captures; byte 2 = keycode, byte 0 = modifiers (Shift). See peripheral-capture.md.
• dnscat2 reassembly: Decode hex/base32 subdomain labels, strip 9-byte dnscat2 header, deduplicate retransmissions, reassemble payload. See network-advanced.md.
• USB keyboard LED exfiltration: Host-to-device HID SET_REPORT packets toggle Caps Lock LED. Timing encodes Morse code. See peripheral-capture.md.

See network.md for SMB3 decryption, credential extraction, and linux-forensics.md for full TLS/TFTP/USB workflows.

Browser Forensics

• Chrome/Edge: Decrypt Login Data SQLite with AES-GCM using DPAPI master key
• Firefox: Query places.sqlite -- SELECT url FROM moz_places WHERE url LIKE '%flag%'

See linux-forensics.md for full browser credential decryption code.

Additional Technique Quick References

• Docker image forensics: Config JSON preserves ALL RUN commands even after cleanup. tar xf app.tar then inspect config blob. See linux-forensics.md.
• Linux attack chains: Check auth.log, .bash_history, recent binaries, PCAP. See linux-forensics.md.
• RAID 5 XOR recovery: Two disks of a 3-disk RAID 5 → XOR byte-by-byte to recover the third: bytes(a ^ b for a, b in zip(disk1, disk3)). See disk-advanced.md.
• GIMP raw memory dump visual inspection: When Volatility fails, open .dmp in GIMP as raw RGB data at monitor width (~1920); scroll to find framebuffer screenshots of user's desktop. See disk-and-memory.md.
• Kyoto Cabinet hash DB forensics: Recover key ordering from KC hash database with zeroed keys by inserting sequential probe keys and binary-diffing to find which hash slot each overwrites. See disk-advanced.md.
• PowerShell ransomware: Extract scripts from minidump, find AES key, decrypt SMTP attachment. See disk-and-memory.md.
• Linux ransomware + memory dump: If Volatility is unreliable, recover AES key via raw-memory candidate scanning and magic-byte validation; re-extract zip cleanly to avoid missing files/false negatives. See disk-advanced.md.
• Deleted partitions: testdisk or kpartx -av. See disk-advanced.md.
• ZFS forensics: Reconstruct labels, Fletcher4 checksums, PBKDF2 cracking. See disk-advanced.md.
• Reassemble BSON (Binary JSON) documents from raw bytes; parse with Python library. See .

SMB RID Recycling via LSARPC (Midnight 2026)

Enumerate AD accounts from PCAP by analyzing LSARPC LsaLookupSids calls with sequential RIDs after Guest auth. Filter: dcerpc.cn_bind_to_str contains lsarpc.

See network-advanced.md for full RPC call sequence and Wireshark filters.

Timeroasting / MS-SNTP Hash Extraction (Midnight 2026)

Extract crackable HMAC-MD5 hashes from MS-SNTP responses by sending NTP requests with machine account RIDs. Crack with hashcat -m 31300.

# Extract NTP payloads, convert to hashcat format, crack
tshark -r capture.pcapng -Y "ntp && ip.src == <DC_IP>" -T fields -e udp.payload
hashcat -m 31300 -a 0 -O hashes.txt rockyou.txt --username

See network-advanced.md for payload parsing script and full attack chain.

HTTP Exfiltration in PCAP

Quick path: tshark --export-objects http,/tmp/objects extracts uploaded files instantly. Check for multipart POST uploads, unusual User-Agent strings, and exfiltrated files (images with flag text). See network.md.

Common Encodings

echo "base64string" | base64 -d
echo "hexstring" | xxd -r -p
# ROT13: tr 'A-Za-z' 'N-ZA-Mn-za-m'

ROT18: ROT13 on letters + ROT5 on digits. Common final layer in multi-stage forensics. See linux-forensics.md for implementation.