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
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/yaklang/hack-skillsnpx agentmods add skills/yaklang/hack-skills/business-logic-vulnerabilitiesWrote 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/business-logic-vulnerabilities)<a href="https://agentmods.dev/skills/yaklang/hack-skills/business-logic-vulnerabilities"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/business-logic-vulnerabilities/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/business-logic-vulnerabilities"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/business-logic-vulnerabilities.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket warn
- Snyk fail
- NVIDIA SkillSpector warn
SkillSpector: 3 findings, up to high
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 →
- high Privilege Escalation · line 688 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.
- medium analysis-evasion · line 1 Suspicious Unicode normalization or mixed-script contentFix: Review the flagged content for security risks. Ensure no credentials, secrets, or sensitive data are exposed.
- medium Excessive Agency · line 303 Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
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 | $0.00037 | $0.07587 |
| Opus 5 | $0.00018 | $0.03793 |
| Sonnet 5 | $0.00007 | $0.01517 |
| Haiku 4.5 | $0.00004 | $0.00759 |
Grade A, and why
business-logic-vulnerabilities scanned grade A with 1 finding 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 9d 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
For each hit, replay the URL anonymously (curl, VLC, flv.js demo at `https://bilibili.github.io/flv.js/demo/`). If the URL plays without a session, you've broken VIP gating. Defense: use signed, short-TTL URLs bound to u Copies of this mod
4 near-identical copies found in the catalogue:
- business-logic-vulnerabilities — 100% identical, 0 lines differ
- business-logic-vulnerabilities — 100% identical, 0 lines differ
- business-logic-vulnerabilities — 100% identical, 0 lines differ
- business-logic-vulnerabilities — 98% identical, 4 lines differ
How it starts
The opening of the file, as written. The whole thing — 712 lines — stays where its author put it; the contents beside it link to each section on GitHub.
SKILL: Business Logic Vulnerabilities — Expert Attack Playbook
AI LOAD INSTRUCTION: Business logic flaws are scanner-invisible and high-reward on bug bounty. This skill covers race conditions, price manipulation, workflow bypass, coupon/referral abuse, negative values, and state machine attacks. These require human reasoning, not automation. For specific exploitation techniques (payment precision/overflow, captcha bypass, password reset flaws, user enumeration), load the companion SCENARIOS.md. For the workflow approach itself (modeling → state machine → attack-surface matrix → human judgement) load METHODOLOGY.md. For the per-module check items load CHECKLIST.md.
Companion files
| File | When to load |
|---|---|
| METHODOLOGY.md | Need the 5-phase workflow, attack-surface 5×N matrix, human-judgement decision tree |
| CHECKLIST.md | Going through a target module-by-module (login / register / payment / IDOR / privacy) and want every line item with why+verify |
| SCENARIOS.md | Drilling deeper into payment precision/overflow, captcha bypass, password reset, enumeration, frontend bypass |
Extended Scenarios
Also load SCENARIOS.md when you need:
- Payment precision & integer overflow attacks — 32-bit overflow to negative, decimal rounding exploitation, negative shipping fees
- Payment parameter tampering checklist — price, discount, currency, gateway, return_url fields
- Condition race practical patterns — parallel coupon application, gift card double-spend with Burp group send
- Captcha bypass techniques — drop verification request, remove parameter, clear cookies to reset counter, OCR with tesseract
- Arbitrary password reset — predictable tokens (
md5(username)), session replacement attack, registration overwrite - User information enumeration — login error message difference, masked data reconstruction across endpoints, base64 uid cookie manipulation
- Frontend restriction bypass — array parameters for multiple coupons (
couponid[0]/couponid[1]), removedisabled/readonlyattributes - Application-layer DoS patterns — regex backtracking, WebSocket abuse
What ships with it
3 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.
- 9d ago First seen · 712 lines · 37 tokens per session scan A 91eb8e5cc29c
business-logic-vulnerabilities is a skill published in the GitHub repository yaklang/hack-skills (2,133 stars, last pushed 2mo ago), licensed MIT. It adds 37 tokens to every session and 7,587 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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