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Discover and exploit broken link hijacking vulnerabilities by identifying references to expired domains, decommissioned cloud resources, and dead external services that can be claimed by an attacker.
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インストールを決める前に、SKILL.md と SkillsMP に表示されている付属ファイルをお読みください。
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npx skills add https://github.com/Undermybelt/hermes-skills --skill broken-link-hjckngコマンドは1行のまま表示されます。コピー前に横へスクロールして全体を確認してください。
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Use when retiring old logic, collapsing duplicate owners, removing fallbacks, or touching schema, persistence, or source-of-truth boundaries while deciding whether to delete old paths, retain compatibility, or stop for confirmation.
Use when defining new features, product behavior, UI/component design, architecture choices, contract changes, or ambiguous medium/high-complexity work before implementation.
Use when the user asks for caveman mode, fewer tokens, brief responses, compressed communication, or otherwise explicitly requests a much shorter answer.
SOC 職業分類に基づく
SKILL.md を表示中
| name | broken-link-hjckng |
| description | Discover and exploit broken link hijacking vulnerabilities by identifying references to expired domains, decommissioned cloud resources, and dead external services that can be claimed by an attacker. |
| domain | cybersecurity |
| subdomain | web-application-security |
| tags | ["broken-link-hijacking","blh","subdomain-takeover","dead-link","expired-domain","supply-chain","external-resource"] |
| version | 1.0 |
| author | mahipal |
| license | Apache-2.0 |
| nist_csf | ["PR.PS-01","ID.RA-01","PR.DS-10","DE.CM-01"] |
Legal Notice: This skill is for authorized security testing and educational purposes only. Unauthorized use against systems you do not own or have written permission to test is illegal and may violate computer fraud laws.
# Use broken-link-checker to find dead links
npx broken-link-checker http://target.com --recursive --ordered \
--exclude-internal --filter-level 3 -o broken_links.txt
# Extract all external links from page source
curl -s http://target.com | grep -oP 'https?://[^"'"'"'\s>]+' | sort -u > all_links.txt
# Extract JavaScript sources
curl -s http://target.com | grep -oP 'src="[^"]*"' | grep -v target.com > external_scripts.txt
# Extract CSS references
curl -s http://target.com | grep -oP 'href="[^"]*\.css"' | grep -v target.com > external_css.txt
# Use wayback machine for historical external references
curl -s "https://web.archive.org/web/timemap/link/http://target.com" | \
grep -oP 'https?://[^>]+' | sort -u > historical_links.txt
# Spider with Burp Suite
# Check if external domains are registered
for domain in $(cat external_domains.txt); do
whois $domain 2>/dev/null | grep -qi "no match\|not found\|available" && \
echo "[CLAIMABLE] $domain"
done
# Check HTTP status of external links
while read url; do
status=$(curl -o /dev/null -s -w "%{http_code}" "$url" --max-time 5)
if [ "$status" = "000" ] || [ "$status" = "404" ]; then
echo "[DEAD] $url (Status: $status)"
fi
done < all_links.txt
# Check for dangling CNAME records
for sub in $(cat subdomains.txt); do
cname=$(dig +short CNAME $sub)
if [ -n "$cname" ]; then
resolved=$(dig +short $cname)
if [ -z "$resolved" ]; then
echo "[DANGLING] $sub -> $cname (UNRESOLVED)"
fi
fi
done
# Check cloud resource availability
# AWS S3 bucket
aws s3 ls s3://target-assets 2>&1 | grep -q "NoSuchBucket" && echo "[CLAIMABLE] S3: target-assets"
# Check GitHub Pages takeover
# If CNAME points to <user>.github.io and 404 is returned
curl -s https://subdomain.target.com | grep -q "There isn't a GitHub Pages site here"
# Check AWS S3 takeover
curl -s http://subdomain.target.com | grep -q "NoSuchBucket"
# Check Azure Blob Storage
curl -s http://subdomain.target.com | grep -q "The specified container does not exist"
# Check Heroku
curl -s http://subdomain.target.com | grep -q "No such app"
# Check Shopify
curl -s http://subdomain.target.com | grep -q "Sorry, this shop is currently unavailable"
# Use subjack for automated takeover detection
subjack -w subdomains.txt -c fingerprints.json -t 100 -o takeover_candidates.txt
# Use nuclei takeover templates
subfinder -d target.com -silent | nuclei -t http/takeovers/ -o takeovers.txt
# Check if external JavaScript domains are available for registration
curl -s http://target.com | grep -oP 'src="https?://([^/"]+)' | \
cut -d'/' -f3 | sort -u | while read domain; do
whois "$domain" 2>/dev/null | grep -qi "no match\|available" && \
echo "[HIJACKABLE SCRIPT] $domain loaded by target.com"
done
# Check npm/CDN package references
curl -s http://target.com | grep -oP 'unpkg\.com/[^@/]+' | sort -u
curl -s http://target.com | grep -oP 'cdn\.jsdelivr\.net/npm/[^@/]+' | sort -u
# Verify if referenced packages still exist
# Check npm registry for deprecated or removed packages
# For expired domain: Register the domain
# For S3 bucket: Create bucket with same name in same region
aws s3 mb s3://target-expired-bucket --region us-east-1
# For GitHub Pages: Create repository with matching name
# Create <org>.github.io repository with proof-of-concept content
# For unclaimed social media: Claim the handle
# Document the takeover with benign proof-of-concept content
# Serve proof-of-concept content
echo "<html><body><h1>Broken Link Hijacking PoC - [Your Name]</h1></body></html>" > index.html
# Upload to claimed resource
# Determine impact based on resource type:
# - External JavaScript: Full XSS on all pages loading the script
# - External CSS: UI defacement, data exfiltration via CSS injection
# - External image/resource: Phishing, tracking
# - CNAME subdomain: Cookie theft, phishing, OAuth bypass
# Check if hijacked resource serves cookies for parent domain
# Check if hijacked subdomain is in OAuth redirect whitelist
# Verify if hijacked domain receives sensitive Referer headers
| Concept | Description |
|---|---|
| Broken Link Hijacking | Claiming control of external resources referenced by target website |
| Dangling CNAME | DNS CNAME record pointing to unclaimed or decommissioned service |
| Subdomain Takeover | Claiming a subdomain by provisioning the service its CNAME points to |
| External Script Hijacking | Registering expired domains that serve JavaScript loaded by target |
| Supply Chain Attack | Compromising external dependencies to inject malicious content |
| Dead Link | URL reference returning 404 or DNS resolution failure |
| Resource Fingerprinting | Identifying specific cloud services from error messages and headers |
| Tool | Purpose |
|---|---|
| broken-link-checker | Automated broken link discovery via web crawling |
| subjack | Subdomain takeover detection tool |
| nuclei | Template-based takeover detection scanner |
| can-i-take-over-xyz | Community database of services vulnerable to takeover |
| BadDNS | DNS auditing tool for detecting domain/subdomain takeovers |
| Wayback Machine | Historical URL analysis for discovering past external references |
## Broken Link Hijacking Report
- **Target**: http://target.com
- **Total External Links**: 145
- **Dead Links**: 12
- **Hijackable Resources**: 3
### Findings
| # | Resource | Type | Status | Impact |
|---|----------|------|--------|--------|
| 1 | analytics.expired-domain.com | JavaScript | Domain available | Full XSS |
| 2 | assets.target.com -> S3 bucket | Static assets | Bucket deleted | Content injection |
| 3 | blog.target.com -> GitHub Pages | Subdomain | No GitHub repo | Subdomain takeover |
### Remediation
- Remove references to decommissioned external resources
- Delete dangling CNAME records for unused subdomains
- Implement Subresource Integrity (SRI) for external scripts
- Regularly audit external dependencies for availability
- Use Content Security Policy to restrict allowed script sources