hunt-open-redirect

hunt-open-redirect is a skill for Claude Code, Codex from uphiago/recon-skills. It costs 53 tokens per session (2,772 once invoked), scanned A, original, MIT.

A security-hunting guide for open redirects, where a website sends visitors to an attacker-chosen URL. It also covers redirects used in login, OAuth, payment, and other flows.

In plain words
What is it for?
It is for checking URL parameters, JavaScript redirects, meta refreshes, and redirect response headers in authorized security testing.
Why use it?
It helps testers find redirects that could support phishing or, when combined with OAuth weaknesses, steal authorization codes or user sessions.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit It is for checking URL parameters, JavaScript redirects, meta refreshes, and redirect response headers in authorized security testing.

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

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/uphiago/recon-skills/hunt-open-redirect"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-open-redirect.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 53 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,772 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 warn 7 Sept 2026
SkillSpector: 1 finding, 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 Privilege Escalation · line 88
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
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 $0.00053 $0.02772
Opus 5 $0.00026 $0.01386
Sonnet 5 $0.00011 $0.00554
Haiku 4.5 $0.00005 $0.00277

Measured 8d ago against content hash 3ff5484391f8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

hunt-open-redirect 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 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.

Makes network callslowCapability

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

LOC=$(curl --max-time 30 --connect-timeout 10 -s -I --max-redirs 0 "$url" | grep -i "^location:")
redteam/hunt-open-redirect/SKILL.md · 236 lines

How it starts

The opening of the file, as written. The whole thing — 236 lines — stays where its author put it; the contents beside it link to each section on GitHub.

HUNT-OPEN-REDIRECT — Open Redirect

When to Use

Use when the target has any redirect parameter — ?url=, ?next=, ?redirect=, ?return=, ?redirect_uri=, or similar — on login/logout flows, OAuth authorization endpoints, language switchers, payment redirects, or any parameter that controls where the user is sent after an action. Open redirect alone is Low on most programs, but becomes Critical when chained to OAuth token theft (redirect_uri bypass) or SSRF escalation. Every OAuth authorization endpoint with a configurable redirect_uri is the highest-value target.

Crown Jewel Targets

Open redirect alone is Low. Chained to OAuth = Critical (ATO).

Highest-value chains:

  • Open redirect → OAuth auth code theft — redirect_uri contains open redirect on trusted domain → auth code sent to attacker → ATO
  • Open redirect → phishing — users trust the URL because it starts with target.com
  • Open redirect → SSRF escalation — if redirect followed server-side → SSRF
  • Open redirect → session fixation — force user to login endpoint with pre-set session

Attack Surface Signals

?redirect=
?next=
?url=
?return=
?returnTo=
?continue=
?dest=
?destination=
?go=
?forward=
?location=
?target=
?redir=
?redirect_uri=
?callback=
?checkout_url=
?success_url=
?cancel_url=
/logout?returnTo=
/login?next=
/sso?callback=

Bypass Table

Technique Payload
Basic https://evil.com
Protocol relative //evil.com
Backslash bypass /\\evil.com
At-sign confusion https://[email protected]
Double slash //evil.com/%2F..
URL encoding %2Fevil.com
Null byte evil.com%00target.com
Whitespace evil.com%09 or %20
JavaScript URI javascript:window.location='https://evil.com'
Data URI data:text/html,<script>window.location='https://evil.com'</script>
Subdomain https://target.com.evil.com
Fragment https://evil.com#.target.com

Common Root Causes

Read the full file on GitHub · 236 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 · 236 lines · 53 tokens per session scan A 3ff5484391f8

Subscribe to this mod's changes

hunt-open-redirect is a skill published in the GitHub repository uphiago/recon-skills (1,254 stars, last pushed 10d ago), licensed MIT. It adds 53 tokens to every session and 2,772 once invoked, about $0.0003 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 2026-09-03.

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