Borrowing it
Nothing to install: this file belongs to zhaji2333/CkSKILLS. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/zhaji2333/CkSKILLS/main/.agents/skills/deserialization-xxe/SKILL.mdgit clone --depth 1 https://github.com/zhaji2333/CkSKILLSWrote 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.
[](https://agentmods.dev/skills/zhaji2333/ckskills/deserialization-xxe)<a href="https://agentmods.dev/skills/zhaji2333/ckskills/deserialization-xxe"><img src="https://agentmods.dev/badge/skills/zhaji2333/ckskills/deserialization-xxe/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.
<a href="https://agentmods.dev/skills/zhaji2333/ckskills/deserialization-xxe"><img src="https://agentmods.dev/badge/skills/zhaji2333/ckskills/deserialization-xxe.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00078 | $0.01047 |
| Opus 5.5 | $0.00031 | $0.00419 |
| Sonnet 5.5 | $0.00016 | $0.00209 |
| Haiku 4.5 | $0.00008 | $0.00105 |
Grade C, and why
deserialization-xxe scanned grade C with 1 finding 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 1mo 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.
Cloud metadata endpointhighServer-side request forgery
One request to 169.254.169.254 can return temporary IAM credentials.
- SSRF：`SYSTEM "http://169.254.169.254/latest/meta-data/"` How it starts
The opening of the file, as written. The whole thing — 101 lines — stays where its author put it; the contents beside it link to each section on GitHub.
deserialization-xxe — 反序列化与解析器漏洞专项深度挖掘
何时调用（触发条件）
- XML 导入/上传、SOAP 接口、Office/Excel 解析
- 序列化数据入口（Java readObject、PHP unserialize、Python pickle、.NET BinaryFormatter）
- JSON 深合并/深拷贝（Node.js 原型污染）
- yaml.load 未指定安全 Loader
- 代码审计发现危险函数（见
source-code-audit）
一、漏洞类型全景
| 类型 | 语言/场景 | 修复 |
|---|---|---|
| H1. 反序列化 | Java/PHP/Python/.NET | 禁用危险反序列化、白名单 |
| H2. XXE | XML导入、SOAP、Office解析 | 禁用外部实体 |
| H3. 原型污染 | Node.js对象合并 | 过滤危险键 |
二、反序列化专项
各语言危险入口
Java: readObject / XMLDecoder / JNDI lookup / JdbcRowSetImpl / TemplatesImpl
PHP: unserialize / phar反序列化
Python: pickle.loads / yaml.load(Loader=Loader)
.NET: BinaryFormatter / XMLSerializer
利用工具
| 语言 | 工具 |
|---|---|
| Java | ysoserial / marshalsec（RMI/LDAP 起服务） |
| PHP | phpggc |
| Python | pickle 手工构造 |
利用链思路
- Java：Gadget 链（CommonsCollections、CommonsBeanutils 等）→ RMI/LDAP 打 JNDI
- PHP：POP 链（Laravel/ThinkPHP/Yii 框架 gadget）+ phar 协议触发
- Python：pickle 反序列化执行命令
- 入口识别：base64/hex 编码的序列化流、
rO0AB（Java）、a:{}（PHP）、O:8:（PHP对象）
三、XXE 专项
基础 Payload
<?xml version="1.0"?>
<!DOCTYPE foo [
<!ENTITY xxe SYSTEM "file:///etc/passwd">
]>
<foo>&xxe;</foo>
进阶利用
- 无回显：外部 DTD + 带外（OOB）读取文件
- SSRF：
SYSTEM "http://169.254.169.254/latest/meta-data/" - 文件读取：
file:///etc/passwd、php://filter/read=convert.base64-encode/resource=config.php - 协议：http/ftp/gopher
- Office 文档 XXE：docx/xlsx 内 XML 注入外部实体
触发场景
- XML/Excel/CSV 导入
- SOAP 接口
- 文档预览/转换
- SVG 上传（图片上传点也测 XXE）
四、原型污染专项（Node.js）
__proto__ / constructor.prototype / constructor.prototype.__proto__
触发场景
- JSON.parse 后深合并（lodash.merge、Object.assign 递归合并）
- 配置合并、查询参数合并
利用思路
- 污染
__proto__.isAdmin=true/__proto__.shell=... - 污染
__proto__.env（pug/ejs 模板引擎 RCE） - 污染
Object.prototype影响全局校验逻辑
五、验证要点
- 反序列化：先确认可控输入点与编码方式，再选 gadget 链验证 RCE
- XXE：先测回显（文件读取），无回显用 OOB DNSLog 验证
- 原型污染：控制台/接口验证
Object.prototype被污染 - 每个 payload 至少尝试到 Level 4 绕过（编码/变形/协议）
六、修复建议
- 禁用危险反序列化或使用白名单/黑名单过滤
- XML 解析禁用外部实体（XXE 防护）
- yaml 使用
SafeLoader - 深合并过滤
__proto__/constructor键 - 输入校验：拒绝序列化对象格式（按业务白名单）
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.
- 1mo ago First seen · 101 lines · 78 tokens per session scan C 01492f968dfa
deserialization-xxe is a skill published in the GitHub repository zhaji2333/CkSKILLS (126 stars, last pushed 1mo ago), licensed MIT. It adds 78 tokens to every session and 1,047 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it C with 1 finding (cloud metadata endpoint). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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