HackSkills is an organized knowledge base of installable skills that gives AI agents practical security knowledge across areas such as web security, privilege escalation, reverse engineering, and digital forensics. It is intended for bug bounty work, penetration testing, CTF competitions, and authorized security research. The catalogue entries are the project's own master, category, and topic skills.
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 yaklang/hack-skills --skill xslt-injectiongit clone --depth 1 https://github.com/yaklang/hack-skillsWrote 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/yaklang/hack-skills/xslt-injection)<a href="https://agentmods.dev/skills/yaklang/hack-skills/xslt-injection"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/xslt-injection.svg" alt="Measured on agentmods" height="20"></a>- Socket pass
- Snyk fail
- NVIDIA SkillSpector warn
SkillSpector: 4 findings, up to critical
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- critical YARA Match · line 159 YARA rule matched a known malware signature (reverse shell, backdoor, ransomware, C2 framework, or info stealer).Fix: Remove the malware payload or compromised file entirely. Investigate how it entered the skill and audit all other artifacts for additional indicators of compromise.
- critical YARA Match · line 164 YARA rule matched a known webshell pattern (PHP, Python, JSP, or ASPX webshell).Fix: Remove the webshell code immediately. Webshells provide unauthorized remote command execution. Audit the skill for additional backdoors or persistence mechanisms.
- high Privilege Escalation · line 66 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 92 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
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 | $0.00056 | $0.02697 |
| Opus 5 | $0.00028 | $0.01349 |
| Sonnet 5 | $0.00011 | $0.00539 |
| Haiku 4.5 | $0.00006 | $0.00270 |
Grade A, and why
xslt-injection 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 4d 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.
Copies of this mod
3 near-identical copies found in the catalogue:
- xslt-injection — 100% identical, 0 lines differ
- xslt-injection — 100% identical, 0 lines differ
- xslt-injection — 98% identical, 4 lines differ
How it starts
The opening of the file, as written. The whole thing — 282 lines — stays where its author put it; the contents beside it link to each section on GitHub.
SKILL: XSLT Injection — Testing Playbook
AI LOAD INSTRUCTION: XSLT injection occurs when attacker-influenced XSLT is compiled/executed server-side. Map the processor family first (Java/.NET/PHP/libxslt). Then chain document(), external entities, EXSLT, or embedded script/extension functions per platform. Authorized testing only; many payloads are destructive. Routing note: if input is generic XML parsing and may not flow through XSLT, cross-load
xxe-xml-external-entity; if you care about outbounddocument(http:...)requests, cross-loadssrf-server-side-request-forgery.
0. QUICK START
- Find sinks: parameters named
xslt,stylesheet,transform,template, SOAP stylesheets, report generators, XML→HTML converters. - Probe reflection: inject unique namespace or
xsl:value-of select="'marker'"— if output changes, execution likely. - Fingerprint processor (§1).
- Escalate by family: document() / XXE (§2–3), EXSLT write (§4), PHP (§5), Java (§6), .NET (§7).
Quick probe (harmless marker):
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
<xsl:value-of select="'XSLT_PROBE_OK'"/>
</xsl:template>
</xsl:stylesheet>
1. VENDOR DETECTION
Use standard system-property reads inside expressions:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text"/>
<xsl:template match="/">
<xsl:text>vendor=</xsl:text><xsl:value-of select="system-property('xsl:vendor')"/>
<xsl:text> version=</xsl:text><xsl:value-of select="system-property('xsl:version')"/>
<xsl:text> vendor-url=</xsl:text><xsl:value-of select="system-property('xsl:vendor-url')"/>
</xsl:template>
</xsl:stylesheet>
Typical fingerprints (examples, not exhaustive):
| Signal | Possible engine |
|---|---|
Apache Software Foundation / Xalan markers |
Xalan (Java) |
Saxonica / Saxon URI hints |
Saxon |
libxslt / GNOME stack |
libxslt (C, often via PHP, nginx modules, etc.) |
| Microsoft URLs / MSXML strings | MSXML / .NET XSLT stack |
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.
- 4d ago First seen · 282 lines · 56 tokens per session scan A 97b26d8032a2
xslt-injection is a skill published in the GitHub repository yaklang/hack-skills (2,120 stars, last pushed 2mo ago), licensed MIT. It adds 56 tokens to every session and 2,697 once invoked, about $0.0003 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 2026-09-03.
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