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- Add scripts/agent.py and references/api-reference.md to all remaining skills - Update all 648 LICENSE files: copyright now reads 'Mahipal' - Add implementing-security-monitoring-with-datadog (new skill with full anatomy) - All 649 skills now have: SKILL.md, LICENSE, scripts/agent.py, references/api-reference.md
99 lines
2.2 KiB
Markdown
99 lines
2.2 KiB
Markdown
# API Reference: Broken Link Hijacking
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## Concept
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Broken Link Hijacking (BLH) occurs when a website links to external resources
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that no longer exist. An attacker can register the expired resource (domain,
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GitHub repo, npm package) to serve malicious content via the trusted site.
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## Hijackable Platforms
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| Platform | Hijack Vector |
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|----------|---------------|
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| GitHub | Register abandoned username/repo |
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| npm | Publish unclaimed package name |
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| PyPI | Register unclaimed package |
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| Twitter/X | Claim abandoned handle |
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| BitBucket | Register abandoned team/repo |
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| Custom domain | Register expired domain |
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## Python requests — Link Checking
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### HEAD Request
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```python
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import requests
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resp = requests.head(url, timeout=10, allow_redirects=True, verify=False)
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# 404 = broken link, potential hijack
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```
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### Connection Error = Domain Takeover
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```python
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try:
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requests.head(url, timeout=5)
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except requests.ConnectionError:
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print("Domain may be unregistered - takeover possible")
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```
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## HTML Link Extraction
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### Regex Patterns
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```python
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import re
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# href links
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re.finditer(r'href=["\']([^"\']+)', html)
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# src links
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re.finditer(r'src=["\']([^"\']+)', html)
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```
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## Domain Availability Check
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### WHOIS Lookup
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```bash
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whois expired-domain.com
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# "No match for" = available for registration
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```
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### DNS Check
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```bash
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dig expired-domain.com +short
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# Empty = no DNS records (likely available)
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```
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## GitHub API — Check Username Availability
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### Check user exists
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```http
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GET https://api.github.com/users/username
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```
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- 200 = exists
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- 404 = available for registration
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### Check repo exists
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```http
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GET https://api.github.com/repos/owner/repo
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```
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## npm Registry — Check Package
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```http
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GET https://registry.npmjs.org/package-name
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```
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- 200 = exists
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- 404 = available for registration
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## Subdomain Takeover Indicators
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### CNAME to Unclaimed Service
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```bash
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dig CNAME old-service.example.com
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# old-service.example.com. CNAME unregistered.herokuapp.com.
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```
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### Common Vulnerable Services
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| Service | Indicator |
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|---------|-----------|
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| GitHub Pages | 404 "There isn't a GitHub Pages site here" |
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| Heroku | "No such app" |
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| AWS S3 | "NoSuchBucket" |
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| Azure | "404 Web Site not found" |
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| Shopify | "Sorry, this shop is currently unavailable" |
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