What is deserialization-analysis?

A security review guide for finding insecure deserialization, where untrusted data is turned into executable or unsafe objects.

Reviewing serialization handlers in Python, Java, .NET, PHP, Ruby, and Node.js, including pickle, ObjectInputStream, YAML, and similar formats.

It helps identify paths that can let an attacker run code by sending crafted requests, files, cookies, or messages.

deserialization-analysis — Skill for Claude Code and Codex by MingyiSe

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add MingyiSecLab/Mingyi-Atlas --skill deserialization-analysis

Clone the repo

git clone --depth 1 https://github.com/MingyiSecLab/Mingyi-Atlas

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/mingyiseclab/mingyi-atlas/deserialization-analysis/github.svg)](https://agentmods.dev/skills/mingyiseclab/mingyi-atlas/deserialization-analysis)

Your own site

<a href="https://agentmods.dev/skills/mingyiseclab/mingyi-atlas/deserialization-analysis"><img src="https://agentmods.dev/badge/skills/mingyiseclab/mingyi-atlas/deserialization-analysis/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/mingyiseclab/mingyi-atlas/deserialization-analysis"><img src="https://agentmods.dev/badge/skills/mingyiseclab/mingyi-atlas/deserialization-analysis.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 63 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,337 The whole file, excluding the scripts and references it only reads on demand.

Security scan B 3 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin 89% copy Near-identical to another mod in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00063	$0.01337
Opus 5	$0.00032	$0.00668
Sonnet 5	$0.00013	$0.00267
Haiku 4.5	$0.00006	$0.00134

Measured 10d ago against content hash 1a871fe354a3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade B, and why

deserialization-analysis scanned grade B with 3 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Sends data to an external URLmediumData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

curl -X POST https://target.com/api/import -H "Content-Type: application/x-java-serialized-object" --data-binary @payload.set

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -X POST https://target.com/api/import -H "Content-Type: application/x-java-serialized-object" --data-binary @payload.set

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

def __reduce__(self): return (os.system, ("id > /tmp/pwn",))

Origin

This is a copy

89% identical to deserialization — 5 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

src/skills/standard/analyst/deserialization-analysis/SKILL.md · 146 lines

How it starts

The opening of the file, as written. The whole thing — 146 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Insecure Deserialization Playbook

Deserialization is the single most reliable path from a byte string under user control to unauthenticated remote code execution. Modern frameworks have tried to wall this off, but chained-gadget attacks (ysoserial, ysoserial.net, marshalsec, phpggc) still make this a top-tier finding.

1. Sources (user-controlled data that becomes an object)

HTTP body, cookie, header, query param
Message queue payload (Kafka, RabbitMQ, SQS)
File upload parsed as config
WebSocket messages
Inter-service RPC

2. Dangerous sinks by language

Python

pickle.loads / pickle.load / pickle.Unpickler
dill.loads, cloudpickle.loads, shelve.open
yaml.load() without Loader=SafeLoader
jsonpickle.decode
numpy.load(allow_pickle=True)
torch.load (loads pickled tensors → RCE)
joblib.load
marshal.loads

grep -rE 'pickle\.loads?\(|yaml\.load\([^)]*Loader=(FullLoader|Loader)?\)|torch\.load\(' /workspace/src
semgrep --config p/insecure-transport --config p/python /workspace/src -o /workspace/sem-deser.sarif

Java

ObjectInputStream.readObject
XMLDecoder.readObject
Jackson ObjectMapper with default typing + polymorphic types
SnakeYAML Yaml.load() (before 2.0) — RCE via !!javax.script.ScriptEngineManager
XStream without whitelist
Hessian, Kryo with registration disabled

Gadgets: ysoserial payloads (CommonsCollections, Spring, Groovy, C3P0)

.NET

BinaryFormatter.Deserialize (deprecated but still common)
SoapFormatter, LosFormatter, ObjectStateFormatter
JavaScriptSerializer with SimpleTypeResolver
Json.NET with TypeNameHandling != None

PHP

unserialize() on any user input
PHAR uploads — file_exists("phar://upload.phar") triggers deser
Laravel decrypt() → unserialize (pre-patched APP_KEY leak chain)

Ruby

Marshal.load
YAML.load (before Psych 4 safe default)
Oj.load without mode: :rails

Node.js

node-serialize unserialize()
serialize-to-js deserialize()
vm.runInNewContext(userInput) — not technically deser but same impact

Read the full file on GitHub · 146 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

10d ago First seen · 146 lines · 63 tokens per session scan B 1a871fe354a3

Subscribe to this mod's changes

deserialization-analysis is a skill published in the GitHub repository MingyiSecLab/Mingyi-Atlas (11 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 63 tokens to every session and 1,337 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it B with 3 findings (sends data to an external url, makes network calls, runs shell commands). It is 89% identical to deserialization, differing in 5 lines, and is treated as a copy.

Security ai-agents ai-hacking ai-pentesting ai-security cybersecurity devsecops

deserialization-analysis