Credential Cracking

You are helping a penetration tester with offline credential and file cracking. This skill covers hash identification, extraction from encrypted files, and cracking with hashcat or john. All operations are local — no target interaction. All testing is under explicit written authorization.

Engagement Logging

Check for ./engagement/ directory. If absent, proceed without logging.

When an engagement directory exists:

• Print [credential-cracking] Activated → <target> to the screen on activation.
• Evidence → save significant output to engagement/evidence/ with descriptive filenames (e.g., sqli-users-dump.txt, ssrf-aws-creds.json).

Scope Boundary

This skill covers offline hash cracking and encrypted file cracking only. It does NOT cover:

• Online password attacks (spraying, brute force) -- use password-spraying
• Credential dumping from memory/registry -- use credential-dumping
• Password guessing against services -- use password-spraying

When cracking is complete, STOP and return to the orchestrator with cracked credentials and recommendations for where to test them.

State Management

Call get_state_summary() from the state MCP server to read current engagement state. Use it to:

• Skip re-testing targets, parameters, or vulns already confirmed
• Leverage existing credentials or access for this technique
• Understand what's been tried and failed (check Blocked section)

Your return summary must include:

• New targets/hosts discovered (with ports and services)
• New credentials or tokens found
• Access gained or changed (user, privilege level, method)
• Vulnerabilities confirmed (with status and severity)
• Pivot paths identified (what leads where)
• Blocked items (what failed and why, whether retryable)

Prerequisites

• Hashes or encrypted files from another skill or user-provided
• hashcat (preferred for GPU-accelerated cracking) or john (john-jumbo for *2john tools)

• Wordlists — check these locations in order:

  1. /usr/share/wordlists/rockyou.txt (Kali default — may be a symlink or compressed .gz)
  2. /usr/share/seclists/Passwords/Leaked-Databases/rockyou.txt (SecLists location)
  3. /usr/share/seclists/Passwords/Leaked-Databases/rockyou.txt.tar.gz (compressed — extract first: tar xzf rockyou.txt.tar.gz)
  4. /opt/seclists/Passwords/ (legacy SecLists path)

  Common issue: /usr/share/wordlists/rockyou.txt is often a broken symlink pointing to /opt/seclists/... which doesn't exist. If the symlink is broken, check /usr/share/seclists/ directly. If rockyou is only available as .tar.gz, extract to $TMPDIR before use.

  If rockyou.txt is not found at ANY of the above locations (including compressed variants), STOP immediately. Do not create custom wordlists or generate passwords. Report the failure:

  [credential-cracking] STOPPED — no wordlist found. Checked: /usr/share/wordlists/rockyou.txt, /usr/share/seclists/Passwords/, /opt/seclists/Passwords/. Install SecLists or provide a wordlist path.

  Return to the orchestrator with this message. The operator must install a wordlist before cracking can proceed.

Sandbox — Disable for All Cracking Commands

hashcat and john need write access to multiple locations: session files (~/.local/share/hashcat/sessions/), potfile (~/.local/share/hashcat/ hashcat.potfile), restore files (CWD), and temp working files. Redirecting each individually with --session, --potfile-path, -o flags is fragile and often still fails.

Always run hashcat and john with dangerouslyDisableSandbox: true. This is the only reliable approach in Claude Code's sandboxed environment.

# CORRECT — disable sandbox for all cracking commands
Bash(command="hashcat -m MODE hash.txt wordlist.txt --force",
     dangerouslyDisableSandbox=true)

Bash(command="john --wordlist=wordlist.txt hash.txt",
     dangerouslyDisableSandbox=true)

# Also for --show after cracking
Bash(command="hashcat -m MODE hash.txt --show",
     dangerouslyDisableSandbox=true)

Do not attempt $TMPDIR workarounds first — go straight to sandbox disable. Cracking is a local-only operation with no security implications from disabling the sandbox.

john-jumbo Requirement

Most *2john extraction tools ship with john-jumbo, not basic john. Check:

john --version 2>&1 | head -1
# Should show "John the Ripper" with "jumbo" in the version string

If john-jumbo is not installed:

# Debian/Ubuntu
sudo apt install john

# Or build from source (last resort)
git clone https://github.com/openwall/john.git
cd john/src && ./configure && make -s clean && make -sj$(nproc)
# Binary at ../run/john

The *2john tools are typically in /usr/share/john/ or alongside the john binary (e.g., /opt/john/run/zip2john). Check with:

find /usr -name "zip2john" 2>/dev/null
find /opt -name "zip2john" 2>/dev/null

Step 1: Identify Hash Type

Determine what needs cracking. This comes from one of two sources:

Source A: Hash from Another Skill

Hashes recovered during the engagement (check get_state_summary() Credentials section):

If the hash type is unclear, use hashcat's built-in identification:

hashcat --identify hash.txt

Or john:

john --list=formats | grep -i <keyword>

Source B: Encrypted File

Password-protected files found during the engagement:

Step 2: Extract Hash (File-Based Formats)

For file-based formats, extract the hash using the appropriate *2john tool.

Extraction Commands

# ZIP
zip2john protected.zip > hash.txt
# Remove the filename prefix if feeding to hashcat:
# zip2john output: archive.zip/file.txt:$pkzip$...
# hashcat needs: $pkzip$...

# Office (2007+ and 97-2003 auto-detected)
office2john protected.docx > hash.txt

# PDF
pdf2john protected.pdf > hash.txt

# KeePass
keepass2john database.kdbx > hash.txt

# SSH key
ssh2john id_rsa > hash.txt

# 7z
7z2john archive.7z > hash.txt

# RAR
rar2john archive.rar > hash.txt

# GPG
gpg2john encrypted.gpg > hash.txt

# Ansible Vault (tool name varies by installation)
ansible2john vault.yml > hash.txt
# Or: ansible2john.py, ansible-vault2john
# Common locations: /usr/share/john/, /opt/john/, alongside john binary
# If the tool is a Python script: python3 /path/to/ansible2john.py vault.yml > hash.txt
#
# For inline vault blocks (not standalone files), extract the block first:
# Copy the $ANSIBLE_VAULT;1.1;AES256 block (hex lines) to a file, then:
# ansible2john extracted_vault.yml > hash.txt

Post-Extraction

1. Verify the hash was extracted successfully:

   cat hash.txt

2. For hashcat, strip the filename prefix (everything before the $ or hash):

   # Example: strip "archive.zip/file.txt:" prefix
   sed 's/^[^:]*://' hash.txt > hash_clean.txt

3. Save to engagement evidence:

   cp hash.txt engagement/evidence/<format>-hash.txt

Step 3: STOP -- Confirm Cracking Approach

Hard stop — never auto-crack. Do not skip this step.

Present the following to the user:

Hash type:     <identified type>
Hash count:    <number of hashes>
Source:        <file name or skill that produced it>

Recommended cracking approach:
  Tool:      <hashcat -m MODE | john --format=FORMAT>
  Wordlist:  <path to wordlist>
  Rules:     <if applicable>
  Command:   <exact command that will be run>

Options:
  a) Crack locally with the command above
  b) Export hash -- save to engagement/evidence/ for external cracking rig

Wait for the user to choose before proceeding. If the user chooses (b), save the hash file, print its path, and return to the orchestrator.

Step 4: Crack

Run the cracking tool chosen by the user.

Sandbox reminder: All hashcat and john commands MUST use dangerouslyDisableSandbox: true. See Prerequisites for details.

CPU-only systems: If no GPU is available, hashcat requires --force to run on CPU. Detect this upfront — don't wait for an OpenCL error:

# Check for GPU
hashcat -I 2>&1 | head -5
# If "No devices found" or only CPU listed, always add --force

Hashcat (GPU-Preferred)

Hashcat is preferred for most hash types due to GPU acceleration.

Common hash modes:

John the Ripper

John is preferred when *2john extraction was used -- john reads the output format directly without stripping prefixes.

# Basic wordlist attack
john --wordlist=/usr/share/wordlists/rockyou.txt hash.txt

# With format specification (if auto-detect fails)
john --format=<format> --wordlist=/usr/share/wordlists/rockyou.txt hash.txt

# Show cracked passwords
john --show hash.txt

Common john formats: NT, netntlmv2, krb5tgs, krb5asrep, sha512crypt, bcrypt, PKZIP, Office, PDF, keepass, SSH, 7z, RAR5.

Wordlists

Locate rockyou.txt (the most common general-purpose wordlist):

# Find rockyou — check all common locations
for f in /usr/share/wordlists/rockyou.txt \
         /usr/share/seclists/Passwords/Leaked-Databases/rockyou.txt \
         /opt/seclists/Passwords/Leaked-Databases/rockyou.txt; do
    [ -f "$f" ] && echo "[+] Found: $f" && break
done

# Check for compressed versions if not found
ls /usr/share/wordlists/rockyou.txt.gz \
   /usr/share/seclists/Passwords/Leaked-Databases/rockyou.txt.tar.gz \
   2>/dev/null

# Extract if compressed
# .gz:     gunzip /usr/share/wordlists/rockyou.txt.gz
# .tar.gz: tar xzf /usr/share/seclists/.../rockyou.txt.tar.gz -C $TMPDIR

SecLists passwords (for targeted cracking):

# Find seclists base directory
SECLISTS=$([ -d /usr/share/seclists ] && echo /usr/share/seclists || echo /opt/seclists)

# Useful wordlists:
# $SECLISTS/Passwords/Common-Credentials/10-million-password-list-top-1000000.txt
# $SECLISTS/Passwords/darkweb2017-top10000.txt
# $SECLISTS/Passwords/xato-net-10-million-passwords-1000000.txt

Escalation Strategy

If a straight wordlist attack fails, escalate. All commands below require dangerouslyDisableSandbox: true and --force on CPU-only systems.

1. Wordlist only (fastest):

   hashcat -m MODE hash.txt /usr/share/wordlists/rockyou.txt --force

2. Wordlist + rules (catches mutations like Password1!):

   # best64 — fast, covers common mutations
   hashcat -m MODE hash.txt /usr/share/wordlists/rockyou.txt -r /usr/share/hashcat/rules/best64.rule
   
   # dive.rule — comprehensive, slower
   hashcat -m MODE hash.txt /usr/share/wordlists/rockyou.txt -r /usr/share/hashcat/rules/dive.rule
   
   # OneRuleToRuleThemAll (download if not present)
   hashcat -m MODE hash.txt /usr/share/wordlists/rockyou.txt -r /usr/share/hashcat/rules/OneRuleToRuleThemAll.rule

   John equivalent:

   john --wordlist=/usr/share/wordlists/rockyou.txt --rules=best64 hash.txt

3. Mask attack (for known patterns):

   # 8-char lowercase + digit + special
   hashcat -m MODE hash.txt -a 3 '?l?l?l?l?l?l?d?s'
   
   # Company name + digits
   hashcat -m MODE hash.txt -a 3 'Company?d?d?d?d'
   
   # Capitalize first, lowercase, digits, special
   hashcat -m MODE hash.txt -a 3 '?u?l?l?l?l?l?d?d?s'

4. Combination attack (two wordlists combined):

   hashcat -m MODE hash.txt -a 1 wordlist1.txt wordlist2.txt

Monitoring Progress

# Hashcat: press 's' for status during run, or:
hashcat -m MODE hash.txt wordlist.txt --status --status-timer=30

# John: press any key for status during run, or:
john --status

Step 5: Post-Crack

Record Results

1. Update state for each cracked hash — do NOT create new credential rows:

   update_credential(id=<hash_credential_id>, cracked=True, secret="<plaintext>")

   This marks the original hash record as cracked and replaces the hash with the plaintext. Get the credential ID from get_credentials() or the task context.
2. Save cracked credentials to evidence:

   # Hashcat
   hashcat -m MODE hash.txt --show > engagement/evidence/cracked-passwords.txt
   
   # John
   john --show hash.txt > engagement/evidence/cracked-passwords.txt

3. Report cracked credentials in your return summary:

   ## Credentials
   - admin:P@ssw0rd1 (cracked from NTLM, source: SAM dump on 10.10.10.5)
   - svc_sql:Summer2024! (cracked from kerberoasting TGS)

Recommend Next Steps

Return to the orchestrator with:

• Cracked credentials and where they came from
• Recommended testing: which services/hosts to test them against (from the engagement state)
• Suggested skills:
  • Credentials work on SMB/WinRM/RDP -> pass-the-hash or password-spraying
  • Domain credentials recovered -> ad-discovery for further enumeration
  • SSH key decrypted -> direct SSH access, then linux-discovery
  • File decrypted (ZIP/Office/KeePass) -> examine contents for more credentials or sensitive data

Troubleshooting

hashcat: No devices found / OpenCL error

hashcat requires GPU drivers. If no GPU is available:

• Use --force to run on CPU (slow but works): hashcat -m MODE hash.txt wordlist.txt --force
• Better: detect this upfront in Step 4 with hashcat -I and always include --force on CPU-only systems. Don't wait for the error.
• Or switch to john (CPU-native): john --wordlist=wordlist.txt hash.txt

hashcat: Permission denied / session file errors in sandbox

Do NOT try to work around with --session $TMPDIR or --potfile-path. Use dangerouslyDisableSandbox: true on ALL hashcat/john commands. See Prerequisites → "Sandbox" section.

john: Unknown ciphertext format

• Specify format explicitly: john --format=<format> hash.txt
• List available formats: john --list=formats
• Ensure john-jumbo is installed (basic john has limited format support)

rockyou.txt not found

# Check all common locations (including broken symlinks)
find /usr/share /opt -name "rockyou*" 2>/dev/null
ls -la /usr/share/wordlists/rockyou.txt  # Check if it's a broken symlink

# SecLists location (most reliable on non-Kali systems)
ls /usr/share/seclists/Passwords/Leaked-Databases/rockyou.txt*

# If only .tar.gz exists
tar xzf /usr/share/seclists/Passwords/Leaked-Databases/rockyou.txt.tar.gz -C $TMPDIR
# Then use: $TMPDIR/rockyou.txt

# If only .gz exists
gunzip /usr/share/wordlists/rockyou.txt.gz

# If missing entirely (Debian/Ubuntu)
sudo apt install wordlists seclists

zip2john / office2john not found

These tools ship with john-jumbo. Check:

# Debian/Ubuntu package location
ls /usr/share/john/zip2john
ls /usr/share/john/office2john.py

# Custom john build
ls /opt/john/run/zip2john

# Or find them
find / -name "zip2john" 2>/dev/null

If the *2john tools are Python scripts, run them with python3:

python3 /usr/share/john/office2john.py protected.docx > hash.txt

Hash format mismatch (hashcat)

Line-length exception / Token length exception / Separator unmatched

• The hash may have a filename prefix from *2john -- strip it
• Wrong hashcat mode -- verify with hashcat --identify hash.txt
• Hash may be truncated -- re-extract from source

Cracking is too slow

• $6$ (SHA-512 crypt), bcrypt, Office 2013+, and KeePass are intentionally slow hashes. Even with GPU, expect low speeds.
• Try a smaller, targeted wordlist first (top 10k passwords)
• Use mask attack if you know the password policy
• Consider exporting to a dedicated cracking rig