hunt-race-condition

hunt-race-condition is a skill for Claude Code, Codex from uphiago/recon-skills. It costs 140 tokens per session (10,693 once invoked), scanned A, original, MIT.

A security-hunting guide for race conditions, where two or more requests arrive close together and break an operation's intended order. Examples include redeeming the same coupon twice or receiving multiple benefits from one payment.

In plain words
What is it for?
It is for testing redemption, voting, account-limit, privilege, deletion, checkout, and token-related workflows.
Why use it?
It helps testers find timing flaws that can bypass limits, duplicate credits, alter permissions, or interfere with deletion and payment processes.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: positional $N argument.

Good fit It is for testing redemption, voting, account-limit, privilege, deletion, checkout, and token-related workflows.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/uphiago/recon-skills/hunt-race-condition
About the project

Recon Skills is a pack of security-testing skills covering reconnaissance, web applications, APIs, authentication, vulnerability validation, cloud infrastructure, and reporting. Security professionals use it for authorized assessments of systems they own or have written permission to test. The catalogue entries are individual skills from the pack.

uphiago/recon-skills · 1,254 stars · on GitHub · hiago.sh

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 uphiago/recon-skills --skill hunt-race-condition
Clone the repo
git clone --depth 1 https://github.com/uphiago/recon-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 hunt-race-condition

README.md
[![agentmods](https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-race-condition/github.svg)](https://agentmods.dev/skills/uphiago/recon-skills/hunt-race-condition)
Your own site
<a href="https://agentmods.dev/skills/uphiago/recon-skills/hunt-race-condition"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-race-condition/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 hunt-race-condition

Your own site · 80×15
<a href="https://agentmods.dev/skills/uphiago/recon-skills/hunt-race-condition"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-race-condition.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 140 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 10,693 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 2 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 4 findings, up to medium

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 →

  • medium Privilege Escalation · line 351
    Commands invoke sudo or root privileges. Verify this elevated access is necessary and justified.
    Fix: Avoid sudo/root unless strictly required. Prefer least-privilege patterns. If elevation is needed, document the justification and scope.
  • medium Privilege Escalation · line 684
    Commands invoke sudo or root privileges. Verify this elevated access is necessary and justified.
    Fix: Avoid sudo/root unless strictly required. Prefer least-privilege patterns. If elevation is needed, document the justification and scope.
  • medium Excessive Agency · line 181
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
  • medium Data Exfiltration · line 118
    Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
    Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
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 $0.00140 $0.10693
Opus 5 $0.00070 $0.05346
Sonnet 5 $0.00028 $0.02139
Haiku 4.5 $0.00014 $0.01069

Measured 8d ago against content hash e658469d7331, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

hunt-race-condition scanned grade A 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 8d 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.

Asks for rootlowPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

1. Capture the loopback or your egress interface during the attack: `sudo tcpdump -i lo0 -w race.pcap port 443` (or interface 0).

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.

- `curl` with `&` backgrounding
redteam/hunt-race-condition/SKILL.md · 756 lines

How it starts

The opening of the file, as written. The whole thing — 756 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Crown Jewel Targets

Race conditions are high-severity findings because they break financial, access control, and integrity assumptions that defenders rarely stress-test. Highest payouts come from:

  • Monetary/credit systems — double-spending gift cards, coupons, referral bonuses, promotional credits, wallet balances
  • Vote/reputation manipulation — upvoting the same content multiple times, gaming leaderboards or trending algorithms
  • Account limits bypass — exceeding free-tier quotas, bypassing "one per user" restrictions on invites, trial activations, or API key generation
  • Privilege escalation — racing role assignment or permission checks during user creation/upgrade flows
  • Deletion bypass — reading or exfiltrating data during a narrow window between "marked for deletion" and "actually deleted"
  • Payment flows — charging a card once but receiving multiple fulfillments

Best-paying asset types: Fintech apps, SaaS platforms with credit/subscription models, social platforms with reputation systems, e-commerce checkout flows, OAuth/SSO token endpoints.


Attack Surface Signals

URL Patterns

/vote, /upvote, /like, /favorite
/redeem, /apply-coupon, /use-code, /claim
/purchase, /checkout, /confirm-order, /pay
/transfer, /withdraw, /send-money
/invite, /referral, /accept-invite
/upgrade, /activate, /trial
/delete, /deactivate, /cancel
/follow, /subscribe

Response Headers That Signal Race-Prone Backends

X-RateLimit-*        # rate limiting exists, but may not be atomic
X-Request-Id         # each request independently tracked
No Cache-Control     # stateful ops not idempotent

JavaScript Patterns to Grep

// Single-use action buttons with client-side disable
button.disabled = true
$('#btn').prop('disabled', true)
// Optimistic UI updates (state set before server confirms)
setState({ used: true })
// Sequential async calls without locking
await useVoucher(); await deductBalance();

Tech Stack Signals

  • Ruby on Rails without with_lock / lock! — ActiveRecord doesn't lock by default
  • Node.js with async/await chains — non-atomic DB reads then writes
  • PHP without SELECT ... FOR UPDATE — common in legacy codebases
  • Microservices — inter-service calls introduce natural TOCTOU windows
  • Redis counters without Lua scripts or INCR atomicity checks
  • Message queues — idempotency keys often missing

Read the full file on GitHub · 756 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. 8d ago First seen · 756 lines · 140 tokens per session scan A e658469d7331

Subscribe to this mod's changes

hunt-race-condition is a skill published in the GitHub repository uphiago/recon-skills (1,254 stars, last pushed 10d ago), licensed MIT. It adds 140 tokens to every session and 10,693 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it A with 2 findings (asks for root, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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