sast-businesslogic

sast-businesslogic is a skill for Claude Code, Codex from utkusen/sast-skills. It costs 110 tokens per session (4,713 once invoked), scanned A, original, MIT.

A security review for finding business-logic vulnerabilities: flaws where valid features can be used to break the application's intended rules.

In plain words
What is it for?
It models threats from the application's domain, checks attack scenarios in batches, and combines the findings into one assessment. It requires an existing architecture analysis.
Why use it?
It looks beyond technical attacks such as injection to find workflow bypasses, price manipulation, and other cases where the code accepts an outcome the business did not intend.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions subagents; installed under .agents/ (shared by several agents).

Good fit It models threats from the application's domain, checks attack scenarios in batches, and combines the findings into one assessment. It requires an existing architecture analysis.

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Install with agentmods
npx agentmods add skills/utkusen/sast-skills/sast-businesslogic
About the project

SAST Skills is a collection of agent workflows that inspect web and mobile application code for security vulnerabilities, where SAST means static application security testing. Developers and security reviewers use it to map a codebase, verify possible flaws, and produce a severity-ranked remediation report. The catalogue entries are the project's vulnerability-detection and reporting skills.

utkusen/sast-skills · 1,309 stars · on GitHub

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.

Any agent
npx skills add utkusen/sast-skills --skill sast-businesslogic
Clone the repo
git clone --depth 1 https://github.com/utkusen/sast-skills

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for sast-businesslogic

README.md
[![agentmods](https://agentmods.dev/badge/skills/utkusen/sast-skills/sast-businesslogic/github.svg)](https://agentmods.dev/skills/utkusen/sast-skills/sast-businesslogic)
Your own site
<a href="https://agentmods.dev/skills/utkusen/sast-skills/sast-businesslogic"><img src="https://agentmods.dev/badge/skills/utkusen/sast-skills/sast-businesslogic/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.

agentmods 80×15 button for sast-businesslogic

Your own site · 80×15
<a href="https://agentmods.dev/skills/utkusen/sast-skills/sast-businesslogic"><img src="https://agentmods.dev/badge/skills/utkusen/sast-skills/sast-businesslogic.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 110 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,713 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 5.1 $0.00110 $0.04713
Opus 5 $0.00055 $0.02357
Sonnet 5 $0.00022 $0.00943
Haiku 4.5 $0.00011 $0.00471

Measured 13d ago against content hash a23b28dc1b72, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

sast-businesslogic 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 13d 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.

> [Step-by-step instructions or curl commands to confirm the finding on the live app.
sast-files/.agents/skills/sast-businesslogic/SKILL.md · 377 lines

How it starts

The opening of the file, as written. The whole thing — 377 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Business Logic Vulnerability Detection

You are performing a focused security assessment to find business logic vulnerabilities in a codebase. This skill uses a three-phase approach with subagents: threat modeling (understand the domain and generate attack scenarios), batched verify (check whether scenarios are exploitable in parallel batches of 3), and merge (consolidate batch results).

Prerequisites: sast/architecture.md must exist. Run the analysis skill first if it doesn't.


What are Business Logic Vulnerabilities

Business logic vulnerabilities arise when an application's intended workflow, rules, or constraints can be manipulated to produce unintended outcomes — without exploiting technical flaws like injection or memory corruption. The attacker operates within the application's own features but uses them in ways the developers did not anticipate.

The core pattern: the application accepts input that is syntactically valid and passes authentication/authorization, but violates a business rule that was never enforced in code.

What Business Logic Vulnerabilities ARE

  • Submitting a negative quantity to a purchase endpoint, receiving a credit instead of a charge
  • Applying the same one-time discount coupon multiple times in parallel requests
  • Skipping the payment step in a multi-step checkout by replaying a later step's request
  • Posting a rating of 9999 to a movie rating endpoint that should cap ratings at 5
  • Transferring a negative amount to move money from the recipient to the sender
  • Redeeming a referral bonus by referring yourself with a second account
  • Re-using a single-use reset token or voucher that was never invalidated
  • Purchasing an item that is out of stock due to a race condition between inventory check and reservation
  • Accessing a premium subscription feature after downgrading to a free plan
  • Winning an auction by retracting a high bid after others have been eliminated

What Business Logic Vulnerabilities are NOT

Read the full file on GitHub · 377 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. 13d ago First seen · 377 lines · 110 tokens per session scan A a23b28dc1b72

Subscribe to this mod's changes

sast-businesslogic is a skill published in the GitHub repository utkusen/sast-skills (1,309 stars, last pushed 5mo ago), licensed MIT. It adds 110 tokens to every session and 4,713 once invoked, about $0.0006 per session on Opus 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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