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/authbypass-authentication-flawsWrote 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/authbypass-authentication-flaws)<a href="https://agentmods.dev/skills/yaklang/hack-skills/authbypass-authentication-flaws"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/authbypass-authentication-flaws.svg" alt="Measured on agentmods" height="20"></a>- Socket warn
- Snyk fail
- NVIDIA SkillSpector warn
SkillSpector: 5 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 201 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 YARA Match · line 201 YARA rule matched a hack tool or exploit indicator (offensive tools, reconnaissance, privilege escalation, or exploit frameworks).Fix: Remove offensive tool references and exploit code. Legitimate agent skills should not contain penetration testing tools, exploit frameworks, or reconnaissance utilities.
- high Tool Misuse · line 227 Tool parameters are crafted to achieve unintended or unsafe behavior. Parameter abuse can bypass intended safety checks (e.g. shell=True, --force, dangerous glob patterns).Fix: Validate all tool parameters against an allowlist. Reject dangerous parameter values (shell=True, --force, -rf /) and use safe defaults.
- medium Tool Misuse · line 2 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.
- medium Excessive Agency · line 257 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 | $0.00043 | $0.03830 |
| Opus 5 | $0.00022 | $0.01915 |
| Sonnet 5 | $0.00009 | $0.00766 |
| Haiku 4.5 | $0.00004 | $0.00383 |
Grade A, and why
authbypass-authentication-flaws 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.
Copies of this mod
4 near-identical copies found in the catalogue:
- authbypass-authentication-flaws — 100% identical, 0 lines differ
- authbypass-authentication-flaws — 100% identical, 0 lines differ
- authbypass-authentication-flaws — 100% identical, 0 lines differ
- authbypass-authentication-flaws — 97% identical, 4 lines differ
How it starts
The opening of the file, as written. The whole thing — 442 lines — stays where its author put it; the contents beside it link to each section on GitHub.
SKILL: Authentication Bypass — Expert Attack Playbook
AI LOAD INSTRUCTION: Expert authentication bypass techniques. Covers SQL injection-based login bypass, password reset flaws, token predictability, account enumeration, brute force bypass, and multi-factor auth bypass. Distinct from JWT/OAuth (covered in ../jwt-oauth-token-attacks/SKILL.md). Focus on the login mechanism itself.
0. AUTHORIZED CREDENTIAL TEST PLANNING
After reducing routing entries, default credentials, username variants, port focus, and wordlist sizing are handled here in one place.
Service-first tiny sets
| Service Type | First Usernames | First Passwords |
|---|---|---|
| phpMyAdmin | root, admin |
empty, root, phpmyadmin, admin |
| FTP | ftp, admin, test |
empty, ftp, admin, 123456 |
| SSH | root, admin, service account names |
root, admin, seasonal variants |
| MySQL | root, mysql |
empty, root, mysql |
| Tomcat / Java admin | tomcat, admin, manager |
tomcat, admin, s3cret |
| WebLogic | weblogic, admin |
weblogic, welcome1, admin |
Username classes
| Class | Examples |
|---|---|
| Generic admins | admin, administrator, root, test, guest |
| Support / ops | dev, ops, sysadmin, service, backup |
| Name-based | firstname, lastname, f.lastname, first.last |
| Mail-derived | left side of corporate email formats |
| Product-based | tomcat, weblogic, jenkins, gitlab |
Wordlist sizing and port focus
| Scenario | Preferred Size | Why |
|---|---|---|
| Default admin panel | 5 to 50 passwords | Defaults beat giant lists here |
| Internal service with known product | vendor-specific small set | Better signal than generic lists |
| Consumer login with weak controls | Top 20 or Top 100 | Fast verification |
| Rate-limited login | tiny list + header/rotation strategy | Preserve attempts |
| Offline hash cracking | large dictionaries | Online brute rules do not apply |
Prioritize common ports and service surfaces: 80/443/8080/8443 admin panels, 22 SSH, 21 FTP, and 3306/5432/6379/27017 data or management services.
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 · 442 lines · 43 tokens per session scan A e930a9b50792
authbypass-authentication-flaws is a skill published in the GitHub repository yaklang/hack-skills (2,120 stars, last pushed 2mo ago), licensed MIT. It adds 43 tokens to every session and 3,830 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 2026-08-30.
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