Automating Dead Link Detection#

We often ignore 404 errors. But in the world of security, a dead link can be a backdoor.

The Security Risk: Broken Link Hijacking#

If your website links to an external resource (e.g., a Facebook page, a GitHub repo, or an S3 bucket) and that resource is deleted, an attacker can claim it.

1. Scenario: You link to twitter.com/myoldaccount.
2. Event: You delete the account.
3. Attack: Attacker registers myoldaccount.
4. Impact: Users clicking the link on your trusted site are taken to the attacker's profile, which can be used for social engineering.

Automating Detection#

You can write a simple Python script to crawl your site and check the status code of every external link.

Copy code
import requests
from bs4 import BeautifulSoup

def check_links(url):
    # ... crawling logic ...
    if response.status_code == 404:
        print(f"[VULN] Dead link found: {link}")

Tools#

• blc (Broken Link Checker): A node.js tool for checking links.
• Burp Suite Spider: Can be configured to report 404s on external domains.

Conclusion#

Keep your digital garden clean. Prune dead links regularly to prevent them from becoming attack vectors.