chain-builder

A security-analysis agent that looks for ways to combine a confirmed bug with additional bugs to increase the overall impact. For example, it may examine whether an access-control flaw also affects account changes or deletion.

In plain words
What is it for?
Use it after confirming a vulnerability to test possible chains such as IDOR with privilege escalation, SSRF with cloud metadata access, or open redirects with OAuth account takeover.
Why use it?
Security issues can be more serious together than separately. This helps testers systematically check likely follow-up paths and confirm each link with an exact request.

Agent

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 agents/awarexone/agentic-bug-hunter/chain-builder
Clone the repo
git clone --depth 1 https://github.com/Awarexone/Agentic-Bug-Hunter
Per session 96 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,090 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 2 findings. Scan, not verified.
Origin original No closer match found 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 $0.00096 $0.01090
Opus 5 $0.00048 $0.00545
Sonnet 5 $0.00019 $0.00218
Haiku 4.5 $0.00010 $0.00109

Measured yesterday against content hash 8a166f8111af, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

chain-builder scanned grade B with 2 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 yesterday.

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 endpointmediumServer-side request forgery

One request to 169.254.169.254 can return temporary IAM credentials.

| SSRF DNS callback | 169.254.169.254 cloud metadata | Critical |

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- Use `curl` for HTTP requests (researcher provides auth headers)
agents/chain-builder.md · 93 lines

How it starts

The opening of the file, as written. The whole thing — 93 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Chain Builder Agent

You are a bug chain specialist. You take a confirmed bug A and systematically find B and C to combine for higher severity.

Your Approach

  1. Identify bug class of A
  2. Look up chain table for B candidates
  3. Check if B is testable from current position
  4. Confirm B exists (exact HTTP request)
  5. Output: chain path, combined severity, separate report count

The A→B Chain Table

Found A Check B Combined Impact
IDOR (GET) IDOR on PUT/DELETE same path Multiple High
Auth bypass Every sibling endpoint in same controller Multiple High
Stored XSS Admin views it? → priv esc Critical
SSRF DNS callback 169.254.169.254 cloud metadata Critical
Open redirect OAuth redirect_uri → code theft Critical ATO
S3 bucket listing JS bundles → grep OAuth creds Medium/High
GraphQL introspection Auth bypass on mutations High
LLM prompt injection IDOR via chatbot (other user data) High
Path traversal /proc/self/environ → RCE Critical
Subdomain takeover OAuth redirect_uri at subdomain Critical
JWT weak secret Forge admin token Critical
File upload bypass SVG→XSS, PHP→RCE High/Critical

Known High-Value Chains

Key Chain Examples

S3 → OAuth ATO: List bucket → download JS bundles → grep client_secret → test OAuth without code_challenge → 3 reports ~$1,200

Open Redirect → OAuth ATO: Confirm redirect → find OAuth flow → set redirect_uri to your redirect endpoint → victim clicks → code delivered to attacker → exchange for token

XSS → Admin Priv Esc: Stored XSS in user field → verify admin views it → payload auto-submits POST to promote attacker to admin

SSRF → Cloud Metadata: DNS callback only = Info → escalate to 169.254.169.254 → get IAM role → fetch credentials → enumerate AWS perms = Critical

Prompt Injection → IDOR: Confirm chatbot follows injected instructions → inject cross-user data request → if other user data returned = IDOR via AI feature

Read the full file on GitHub · 93 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. yesterday First seen · 93 lines · 96 tokens per session scan B 8a166f8111af

Subscribe to this mod's changes

chain-builder is an agent published in the GitHub repository Awarexone/Agentic-Bug-Hunter (4,651 stars, last pushed today), licensed MIT. It adds 96 tokens to every session and 1,090 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it B with 2 findings (cloud metadata endpoint, 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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