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ClaudSkills / Security / web-security

Defend Open Redirect

Category: Security  ·  Sub-category: web-security  ·  Last updated:
Defensive methodology for open redirect (CWE-601) abuse, where a link on a trusted domain sends the victim off-site via a redirect parameter, used to cloak phishing behind your brand (MITRE ATT&CK T1566.002, T1204.001) and to steal OAuth authorization codes and tokens through an attacker-controlled redirect_uri (T1528). Keys off web server, reverse-proxy, and WAF access logs (nginx, Apache, IIS), 30x responses with an off-domain Location header, IdP sign-in logs (Entra ID, Okta), and Defender for Office 365 UrlClickEvents. Gives the defender view, signal-carrying log fields, a redirect-endpoint hunt, and allowlist and token-leak hardening. Use when hardening a redirect, returnUrl, or next parameter, reviewing OAuth redirect_uri validation, hunting phishing links cloaked by your own domain, investigating an off-site Location header, or preventing code and token leakage via Referer.
Security AStatic scan found no risk patternsHow grading works ›

What this skill does

Defend Open Redirect is a community-contributed Claude Code skill in the web-security sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/defend-open-redirect/ and loads when your prompt matches the skill's trigger.

When to invoke it: Use when hardening a redirect, returnUrl, or next parameter, reviewing OAuth redirect_uri validation, hunting phishing links cloaked by your own domain, investigating an off-site Location header, or preventing code and token leakage via Referer.

Who uses this skill

The Defend Open Redirect Claude Code skill is built for security engineers, penetration testers, DevSecOps practitioners, and development teams hardening codebases and infrastructure. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 211,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/defend-open-redirect
curl -L https://claudskills.com/skills/defend-open-redirect/SKILL.md \
  -o ~/.claude/skills/defend-open-redirect/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/defend-open-redirect/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/defend-open-redirect/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\defend-open-redirect\SKILL.md on Windows. See the full install guide for step-by-step instructions.

Telegram

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the Defend Open Redirect Claude Code skill?
Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/defend-open-redirect/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.
What does the Defend Open Redirect skill do?
Defensive methodology for open redirect (CWE-601) abuse, where a link on a trusted domain sends the victim off-site via a redirect parameter, used to cloak phishing behind your brand (MITRE ATT&CK T1566.002, T1204.001) and to steal OAuth authorization codes and tokens through an attacker-controlled redirect_uri (T1528). Keys off web server, reverse-proxy, and WAF access logs (nginx, Apache, IIS), 30x responses with an off-domain Location header, IdP sign-in logs (Entra ID, Okta), and Defender for Office 365 UrlClickEvents. Gives the defender view, signal-carrying log fields, a redirect-endpoint hunt, and allowlist and token-leak hardening. Use when hardening a redirect, returnUrl, or next parameter, reviewing OAuth redirect_uri validation, hunting phishing links cloaked by your own domain, investigating an off-site Location header, or preventing code and token leakage via Referer.
Is this skill free to install?
Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.
When should I use the Defend Open Redirect skill?
Use Defend Open Redirect when your Claude Code task falls under the Security category — specifically in the web security area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Defend Open Redirect" or describe the task and let Claude pick). Browse related skills at /category/security/.
What is a Claude Code skill and how does the Defend Open Redirect skill fit in?
A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Defend Open Redirect is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Security category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA
umbrasec-labs. (2026). Defend Open Redirect [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/defend-open-redirect/
BibTeX
@misc{defend-open-redirect-2026,
  author    = {umbrasec-labs},
  title     = {Defend Open Redirect [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/defend-open-redirect/}
}

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Security scan

Grade A · scanned 2026-10-25 — free static scan against the OWASP Agentic Skills Top 10.

The scan flagged 1 of 10 categories (data-exfil), including a high-severity pattern. Patterns shown inside code fences are weighted as examples rather than instructions — read the grading methodology for what this does and does not guarantee.

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[![Security: A](https://img.shields.io/badge/Security-A-2e7d32)](https://claudskills.com/skills/defend-open-redirect/#security)

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Browse all Security skills in the ClaudSkills registry, or explore these other picks from the same category:

Browse all Security skills → Top 100 skills
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