trailmark-variant-neighborhood
Expands one confirmed or suspected vulnerability into a Trailmark graph neighborhood of variant candidates by finding sibling functions, shared callers and callees, common sensitive sinks, common entrypoint paths, interface implementations, override relationships, type/reference neighbors, and structurally similar nodes. Use after one issue is found to seed variant-analysis, semgrep-rule-creator, static-analysis, or manual review with graph-derived candidate locations.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/trailofbits/skills --skill trailmark-variant-neighborhood- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads trailmark-variant-neighborhood automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
Trailmark Variant Neighborhood
Expand one seed issue into graph-derived variant candidates. This skill generates review targets, not confirmed findings.
When to Use
- A finding is confirmed or plausible and variants may exist
- The vulnerable pattern depends on call context
- The issue involves a shared sink, source, validator, interface, override, trait, hook, handler, adapter, or critical type
- The next step is to seed
variant-analysis,semgrep-rule-creator,static-analysis, or manual review
When NOT to Use
- No seed issue exists. Use discovery or triage first.
- The pattern is purely syntactic and already obvious. Use
semgrep-rule-creatordirectly. - The question is exploit-chain composition across multiple findings. Use a composition workflow.
- The goal is remediation verification. Use a remediation-review workflow.
- The seed cannot be bound to a graph node.
Rationalizations to Reject
| Rationalization | Why It Is Wrong | Required Action |
|---|---|---|
| "Nearby code means variant" | Proximity is only a candidate reason | Rank it as a review target |
| "Only exact same names matter" | Variants often share sinks or preconditions, not names | Expand across callers, callees, interfaces, and types |
| "Every candidate is a finding" | This skill outputs candidates for review | Avoid vulnerability claims |
| "Unreachable candidates can be ignored completely" | They may become reachable after refactors | Rank lower or list as deferred |
| "Graph candidates replace semantic pattern work" | Graph structure finds locations, not root-cause semantics | Hand off to variant-analysis, Semgrep, CodeQL, or manual review |
Workflow
Variant Neighborhood Progress:
- [ ] Step 1: Normalize and bind the seed
- [ ] Step 2: Expand graph neighborhoods
- [ ] Step 3: Rank candidates
- [ ] Step 4: Extract variant pattern guidance
- [ ] Step 5: Emit handoff packet
Step 1: Normalize And Bind The Seed
Accept finding text, file/line, function name, or output from
trailmark-finding-triage. Bind the seed to a Trailmark node and record the
root cause in plain language.
If the seed has no concrete graph binding, stop before inventing variants.
Step 2: Expand Neighborhoods
Use the dimensions in references/neighborhood-patterns.md:
- shared callers
- shared callees and sinks
- entrypoint path neighbors
- interface, override, trait, and implementation siblings
- file or module cluster neighbors
- taint or privilege-boundary peers
- type and state-reference neighbors
Bound expansion to avoid candidate floods.
Step 3: Rank Candidates
Rank with references/ranking.md. Prioritize entrypoint-reachable, tainted, boundary-adjacent, high-blast-radius, shared sink, same-interface, and close-distance candidates. Penalize test, mock, generated, vendor, unreachable, and trusted-internal-only candidates.
Step 4: Extract Pattern Guidance
Summarize what should be searched for syntactically and what requires semantic review. Identify whether follow-up belongs in:
variant-analysissemgrep-rule-creatorstatic-analysiswith CodeQL or SARIF-producing tools- manual review
Step 5: Emit Handoff Packet
Use references/output-format.md. Include ranked candidates, inclusion reasons, exclusions, limitations, and the variant-analysis handoff.
Stop Conditions
- No graph binding exists
- Candidate count is too high and the root cause is underspecified
- Trailmark cannot analyze the target language
- The seed is only in test, generated, or vendor code and the user did not say that code is in scope
FAQ
What does the trailmark-variant-neighborhood skill do?
Expands one confirmed or suspected vulnerability into a Trailmark graph neighborhood of variant candidates by finding sibling functions, shared callers and callees, common sensitive sinks, common entrypoint paths, interface implementations, override relationships, type/reference neighbors, and structurally similar nodes. Use after one issue is found to seed variant-analysis, semgrep-rule-creator, static-analysis, or manual review with graph-derived candidate locations.
How do I install trailmark-variant-neighborhood?
Run npx skills add https://github.com/trailofbits/skills --skill trailmark-variant-neighborhood in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/trailmark-variant-neighborhood/ (personal) or .claude/skills/trailmark-variant-neighborhood/ (project).
Which AI agents can use trailmark-variant-neighborhood?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is trailmark-variant-neighborhood safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains trailmark-variant-neighborhood?
It is published by trailofbits in trailofbits/skills. It has 1,318 recorded installs.
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