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 xss-cross-site-scriptinggit 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/xss-cross-site-scripting)<a href="https://agentmods.dev/skills/yaklang/hack-skills/xss-cross-site-scripting"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/xss-cross-site-scripting/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/yaklang/hack-skills/xss-cross-site-scripting"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/xss-cross-site-scripting.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket fail
- Snyk fail
- NVIDIA SkillSpector warn
SkillSpector: 2 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 321 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.
- medium Tool Misuse · line 28 Tool defaults are unsafe or overly permissive (e.g. disabled TLS verification, no authentication, world-writable permissions). Unsafe defaults widen the attack surface.Fix: Override unsafe defaults with secure settings (verify=True, auth required, restrictive permissions). Review and harden all tool configurations.
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 | $0.00036 | $0.03735 |
| Opus 5 | $0.00018 | $0.01868 |
| Sonnet 5 | $0.00007 | $0.00747 |
| Haiku 4.5 | $0.00004 | $0.00374 |
Grade A, and why
xss-cross-site-scripting 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 5d 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
2 near-identical copies found in the catalogue:
- xss-cross-site-scripting — 100% identical, 0 lines differ
- xss-cross-site-scripting — 95% identical, 4 lines differ
How it starts
The opening of the file, as written. The whole thing — 380 lines — stays where its author put it; the contents beside it link to each section on GitHub.
SKILL: Cross-Site Scripting (XSS) — Expert Attack Playbook
AI LOAD INSTRUCTION: This skill covers non-obvious XSS techniques, context-specific payload selection, WAF bypass, CSP bypass, and post-exploitation. Assume the reader already knows
<script>alert(1)</script>— this file only covers what base models typically miss. For real-world CVE cases, HttpOnly bypass strategies, XS-Leaks side channels, and session fixation attacks, load the companion SCENARIOS.md.
0. RELATED ROUTING
Extended Scenarios
Also load SCENARIOS.md when you need:
- Django debug page XSS (CVE-2017-12794) — duplicate key error → unescaped exception → XSS
- UTF-7 XSS for legacy IE environments (
+ADw-script+AD4-) - HttpOnly bypass methodology — proxy-the-browser, session riding, CSRF-via-XSS
- XS-Leaks side channel attacks — timing oracle, cache probing,
performance.now()measurement - Session fixation via XSS — pre-set session ID before victim login
- DOM clobbering techniques for CSP-restricted environments
Advanced Tricks
Also load ADVANCED_XSS_TRICKS.md when you need:
- mXSS / DOMPurify bypass — namespace confusion,
<noscript>parsing differential, form/table restructuring - DOM Clobbering — property override via
id/name, HTMLCollection, deep property chains - Modern framework XSS — React
dangerouslySetInnerHTML, Vuev-html, AngularbypassSecurityTrust*, Next.js SSR - Trusted Types bypass — default policy abuse, non-TT sinks, policy passthrough
- Service Worker XSS persistence — malicious SW registration, fetch interception, post-patch survival
- PDF/SVG/MathML XSS vectors, polyglot payloads, browser-specific tricks
- XS-Leaks & side channels — timing oracle, frame counting, cache probing, error event oracle
Before broad payload spraying, you can first load:
- upload insecure files when you need the full upload path: validation, storage, preview, and sharing behavior
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 5d ago First seen · 380 lines · 36 tokens per session scan A 7ff26b11d7ef
xss-cross-site-scripting is a skill published in the GitHub repository yaklang/hack-skills (2,133 stars, last pushed 2mo ago), licensed MIT. It adds 36 tokens to every session and 3,735 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 2026-09-03.
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