xxe-attacker

A security-review agent that uses static analysis, examining source code without running it, to detect XML External Entity vulnerabilities. These flaws can let crafted XML read files, make network requests, or consume excessive resources.

In plain words
What is it for?
Use it to check PHP, Python, Java, Node.js, and Go code for unsafe XML parser settings and classify common XXE attack types.
Why use it?
It helps reveal unsafe XML parsing before an attacker can exploit external entities through uploaded or otherwise untrusted XML.

Agent

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.

agentmods
npx agentmods add agents/morodomi/dev-crew/xxe-attacker
Clone the repo
git clone --depth 1 https://github.com/morodomi/dev-crew
Per session 30 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,145 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5 $0.00030 $0.01145
Opus 5 $0.00015 $0.00573
Sonnet 5 $0.00006 $0.00229
Haiku 4.5 $0.00003 $0.00114

Measured yesterday against content hash 1306aced88fe, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

xxe-attacker 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 yesterday.

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.

agents/xxe-attacker.md · 105 lines

How it starts

The opening of the file, as written. The whole thing — 105 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Detection Targets

Type Description Risk
classic-xxe 外部エンティティによるファイル読み取り High
blind-xxe OOBデータ送信 High
xxe-dos Billion Laughs / Quadratic Blowup Medium
ssrf-xxe XXE経由のSSRF High

Framework Detection Patterns

Language Vulnerable Pattern Safe Pattern
PHP simplexml_load_string($input) libxml_disable_entity_loader(true) (PHP 7.x)
PHP loadXML($input, LIBXML_NOENT) loadXML($input) without LIBXML_NOENT
Python lxml.etree.parse(input) defusedxml.parse()
Python xml.sax.parse(input) xml.etree.ElementTree (safe by default)
Java DocumentBuilderFactory.newInstance() setFeature("external-general-entities", false)
Java SAXParserFactory.newInstance() setFeature("external-parameter-entities", false)
Java XMLReader.parse(input) setFeature("disallow-doctype-decl", true)
Node.js libxmljs.parseXml(input) xml2js (safe by default)
Go xml.NewDecoder(input) Disable entity resolution manually

Dangerous Patterns

patterns:
  # PHP - simplexml (XXE vulnerable by default)
  - 'simplexml_load_(string|file)\s*\('
  # PHP - DOMDocument with LIBXML_NOENT
  - '(loadXML|->load)\s*\([^)]*LIBXML_NOENT'
  # Python - lxml (resolve_entities=True by default)
  - 'lxml\.etree\.(parse|fromstring)\s*\('
  - 'etree\.XMLParser\s*\('
  # Python - xml.sax (external entities enabled)
  - 'xml\.sax\.parse(String)?\s*\('
  # Java - DocumentBuilderFactory/SAXParserFactory/XMLReader (XXE by default)
  - 'DocumentBuilderFactory\.newInstance\s*\('
  - 'DocumentBuilder\s*\.\s*parse\s*\('
  - 'SAXParserFactory\.newInstance\s*\('
  - 'SAXParser\s*\.\s*parse\s*\('
  - '(XMLReader\s*\.\s*parse|createXMLReader)\s*\('
  # Go - encoding/xml
  - 'xml\.(NewDecoder|Unmarshal)\s*\('
  # Node.js - libxmljs (XXE enabled)
  - 'libxmljs\.parseXml(String)?\s*\('

Safe Patterns

safe_patterns:
  # PHP - Entity loader disabled (PHP 7.x, deprecated 8.0, removed 8.2)
  - 'libxml_disable_entity_loader\s*\(\s*true'
  - 'LIBXML_NONET'
  # Python - defusedxml / ElementTree (safe by default)
  - 'defusedxml\.'
  - 'defused\..*parse'
  - 'xml\.etree\.ElementTree'
  - 'ET\.(parse|fromstring)'
  # Java - Secure configuration
  - 'setFeature\s*\([^)]*external-general-entities[^)]*false'
  - 'setFeature\s*\([^)]*external-parameter-entities[^)]*false'
  - 'setFeature\s*\([^)]*disallow-doctype-decl[^)]*true'
  - 'setFeature\s*\([^)]*load-external-dtd[^)]*false'
  # Go
  - 'Strict\s*=\s*true'
  - 'Entity\s*=\s*nil'
  # Node.js - xml2js (safe by default)
  - 'xml2js\.'
  - 'parseString\s*\('

Read the full file on GitHub · 105 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.

  1. yesterday First seen · 105 lines · 30 tokens per session scan A 1306aced88fe

Subscribe to this mod's changes

xxe-attacker is an agent published in the GitHub repository morodomi/dev-crew (1 stars, last pushed 3d ago), licensed MIT. It adds 30 tokens to every session and 1,145 once invoked, about $0.0002 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.