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 hash-attack-techniquesgit 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/hash-attack-techniques)<a href="https://agentmods.dev/skills/yaklang/hack-skills/hash-attack-techniques"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/hash-attack-techniques/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/hash-attack-techniques"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/hash-attack-techniques.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket warn
- Snyk pass
- NVIDIA SkillSpector warn
SkillSpector: 1 finding, 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 YARA Match · line 386 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.
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 | $0.00046 | $0.03962 |
| Opus 5.5 | $0.00018 | $0.01585 |
| Sonnet 5.5 | $0.00009 | $0.00792 |
| Haiku 4.5 | $0.00005 | $0.00396 |
Grade A, and why
hash-attack-techniques 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 1mo 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.
requests.get(url, params={**data, "mac": candidate}) Copies of this mod
6 near-identical copies found in the catalogue:
- hash-attack-techniques — 100% identical, 0 lines differ
- hash-attack-techniques — 100% identical, 0 lines differ
- hash-attack-techniques — 100% identical, 0 lines differ
- hash-attack-techniques — 100% identical, 0 lines differ
- hash-attack-techniques — 100% identical, 0 lines differ
- hash-attack-techniques — 92% identical, 6 lines differ
How it starts
The opening of the file, as written. The whole thing — 492 lines — stays where its author put it; the contents beside it link to each section on GitHub.
SKILL: Hash Attack Techniques — Expert Cryptanalysis Playbook
AI LOAD INSTRUCTION: Expert hash attack techniques for CTF and security assessments. Covers length extension attacks, MD5/SHA1 collision generation, meet-in-the-middle hash attacks, HMAC timing side channels, birthday attacks, and proof-of-work solving. Base models often incorrectly apply length extension to HMAC or SHA-3, or fail to distinguish between identical-prefix and chosen-prefix collisions.
0. RELATED ROUTING
- rsa-attack-techniques when hash weaknesses affect RSA signature schemes
- symmetric-cipher-attacks when hash is used in key derivation
- classical-cipher-analysis when analyzing hash-like constructions in classical ciphers
Quick attack selection
| Scenario | Attack | Tool |
|---|---|---|
H(secret || msg) known, extend message |
Length extension | HashPump, hash_extender |
| Need two files with same MD5 | Identical-prefix collision | fastcoll |
| Need specific MD5 prefix match | Chosen-prefix collision | hashclash |
| Byte-by-byte HMAC comparison | Timing attack | Custom script |
| Find any collision | Birthday attack | O(2^(n/2)) |
| Proof of work: find hash with leading zeros | Brute force | hashcat, Python |
1. LENGTH EXTENSION ATTACK
1.1 Vulnerable vs Non-Vulnerable
| Hash | Vulnerable | Why |
|---|---|---|
| MD5 | Yes | Merkle-Damgard construction |
| SHA-1 | Yes | Merkle-Damgard construction |
| SHA-256 | Yes | Merkle-Damgard construction |
| SHA-512 | Yes | Merkle-Damgard construction |
| SHA-3 / Keccak | No | Sponge construction |
| HMAC-* | No | Double hashing prevents extension |
| SHA-256 truncated | No (if truncated) | Missing internal state bits |
| BLAKE2 | No | Different construction |
1.2 Attack Mechanism
Given: MAC = H(secret || original_message)
Known: original_message, len(secret), MAC value
Compute: H(secret || original_message || padding || extension)
WITHOUT knowing the secret!
How: The MAC value IS the internal hash state after processing
(secret || original_message || padding).
Initialize hash with this state, continue hashing extension.
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.
- 1mo ago First seen · 492 lines · 46 tokens per session scan A 0a6177b6ab81
hash-attack-techniques is a skill published in the GitHub repository yaklang/hack-skills (2,521 stars, last pushed 1mo ago), licensed MIT. It adds 46 tokens to every session and 3,962 once invoked, about $0.0002 per session on Opus 5.5. 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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