hunt-brute-force

hunt-brute-force is a skill for Claude Code, Codex from uphiago/recon-skills. It costs 127 tokens per session (5,372 once invoked), scanned B, original, MIT.

A security-testing guide for missing or weak rate limits. Rate limiting restricts how often someone can try an action, such as logging in, entering a one-time code, or requesting a password reset.

In plain words
What is it for?
Use it to test login, OTP and two-factor codes, password-reset tokens, usernames, email addresses, coupons, gift cards, and referral codes.
Why use it?
It helps identify brute-force and account-enumeration flaws that can enable account takeover or reveal valid users.

Skill for Claude CodeCodex

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

Good fit Use it to test login, OTP and two-factor codes, password-reset tokens, usernames, email addresses, coupons, gift cards, and referral codes.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/uphiago/recon-skills/hunt-brute-force
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-brute-force
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-brute-force

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/uphiago/recon-skills/hunt-brute-force"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-brute-force.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 127 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,372 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 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: 8 findings, up to high

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 →

  • high YARA Match · line 227
    YARA rule matched a hack tool or exploit indicator (offensive tools, reconnaissance, privilege escalation, or exploit frameworks).
    Fix: Remove offensive tool references and exploit code. Legitimate agent skills should not contain penetration testing tools, exploit frameworks, or reconnaissance utilities.
  • medium Data Exfiltration · line 55
    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.
  • medium Data Exfiltration · line 137
    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.
  • medium Data Exfiltration · line 143
    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.
  • medium Data Exfiltration · line 144
    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.
  • medium Data Exfiltration · line 145
    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.
  • medium Data Exfiltration · line 157
    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.
  • medium Data Exfiltration · line 198
    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 $0.00127 $0.05372
Opus 5 $0.00063 $0.02686
Sonnet 5 $0.00025 $0.01074
Haiku 4.5 $0.00013 $0.00537

Measured 8d ago against content hash b2c334b4ff7a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade B, and why

hunt-brute-force 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 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.

Sends data to an external URLmediumData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

curl --max-time 30 --connect-timeout 10 -s -X POST "https://$TARGET/forgot-password" -d "email=$VALID_USER" | grep -i "sent\|exist\|not found\|registered"

Makes network callslowCapability

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

CODE_RESP=$(curl --max-time 30 --connect-timeout 10 -s -o /tmp/bf_body -w "%{http_code} %{time_total}" \
redteam/hunt-brute-force/SKILL.md · 317 lines

How it starts

The opening of the file, as written. The whole thing — 317 lines — stays where its author put it; the contents beside it link to each section on GitHub.

HUNT-BRUTE-FORCE — Rate Limiting / Brute Force / Enumeration

Grounding note: this skill is built from published technique classes, not from a curated set of named HackerOne reports. report_count is intentionally 0 — do not cite an exact payout or report ID you cannot verify. Where a public case is well-documented (e.g. Laxman Muthiyah's Instagram password-reset OTP race/rotation research, 2019–2021), it is named below as a technique reference, not a payout claim.

Crown Jewel Targets

OTP brute force (6-digit = 1,000,000 combinations) with no effective rate limit = Critical ATO bypass.

Highest-value chains:

  • OTP / 2FA brute → MFA bypass → ATO — no effective rate limit on /verify-otp, full 000000–999999 keyspace reachable
  • Password-reset token brute — short/predictable/non-expiring tokens + no rate limit → ATO (the Instagram 2019 case combined a 6-digit reset code, no rate limit per request-source, and IP rotation to make 10^6 tractable)
  • Username/email enumeration → targeted credential stuffing — valid/invalid distinguishable by response string, status code, or timing, then sprayed with breach corpora
  • Coupon / gift-card / referral code brute — no rate limit on code validation → financial impact
  • ReDoS — attacker-controlled input hits a catastrophic-backtracking regex → CPU exhaustion → DoS

CRITICAL: Four rate-limit states — do not collapse them

A 200/401 with no 429 does not mean "no rate limiting". A rate-limiting skill that only checks for 429/lockout produces false negatives. Classify the defense BEFORE concluding, by sending a burst of ~50 requests and watching the full response (status, body, headers, latency, and downstream success):

State Signal Brute still feasible?
Hard account lockout account disabled after N fails; later correct creds also fail No (but lockout itself can be a DoS finding)
Soft IP throttle 429 / increasing latency keyed on source IP only Yes — bypass via header/IP rotation (Phase 4)
CAPTCHA injection 200 but body switches to a CAPTCHA challenge after N Maybe — check if the verify endpoint enforces it server-side or if the API path skips it
Silent shadow-throttle 200/401 returned for every request, but submissions are dropped — the genuinely-correct OTP/password stops being accepted, or responses become canned This is the trap. A naive loop sees "all 200, no 429" and reports "no rate limit" — false.

Read the full file on GitHub · 317 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 · 317 lines · 127 tokens per session scan B b2c334b4ff7a

Subscribe to this mod's changes

hunt-brute-force is a skill published in the GitHub repository uphiago/recon-skills (1,254 stars, last pushed 10d ago), licensed MIT. It adds 127 tokens to every session and 5,372 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it B with 2 findings (sends data to an external url, 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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