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Subdomain takeover is a critical security issue where an attacker can claim a subdomain that is no longer in use but still points to a vulnerable third-party service. Detecting such vulnerabilities early can prevent potential exploitation.
Command Breakdown
The following one-liner helps detect subdomain takeovers efficiently:
subfinder -d hackerone.com -silent | dnsprobe -silent -f domain | httprobe -prefer-https | nuclei -t nuclei-templates/subdomain-takeover/detect-all-takeovers.yaml
#### **Explanation of Tools & Steps:**
1. **`subfinder`** – Discovers subdomains of `hackerone.com`.
subfinder -d hackerone.com -silent
dnsprobe– Resolves the discovered subdomains to check their DNS records.dnsprobe -silent -f domain
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httprobe– Checks which subdomains are live via HTTP/HTTPS.httprobe -prefer-https
-
nuclei– Scans for subdomain takeover vulnerabilities using predefined templates.nuclei -t nuclei-templates/subdomain-takeover/detect-all-takeovers.yaml
### **You Should Know:**
#### **Manual Verification Steps**
If you suspect a subdomain takeover, manually verify by:
– Checking DNS records:
dig CNAME suspicious.example.com
– If it points to a deleted cloud service (e.g., AWS S3, GitHub Pages), you may claim it.
#### **Preventive Measures**
- Remove unused DNS records:
</li> </ul> <h1>For Linux DNS management:</h1> sudo nano /etc/bind/db.example.com
– Monitor subdomains regularly:
<h1>Use cron to automate subdomain checks:</h1> 0 * * * * /path/to/subdomain_monitor_script.sh
#### **Additional Recon Commands**
- MassDNS for large-scale DNS resolution:
massdns -r resolvers.txt -t A -o S domains.txt > results.txt
- Aquatone for visual subdomain analysis:
cat subdomains.txt | aquatone -out ./aquatone_report
### **What Undercode Say**
Subdomain takeovers remain a low-hanging fruit for attackers. Automation tools like
subfinder,nuclei, and `httprobe` make detection easier, but manual verification is crucial. Always:
– Audit DNS configurations regularly.
– Use monitoring scripts to detect dangling records.
– Harden cloud services (AWS S3, Heroku, etc.) to prevent misconfigurations.#### **Expected Output:**
[INF] [subdomain-takeover] Possible subdomain takeover at http://legacy.example.com (CNAME: deleted.cloudservice.com)
**Relevant URLs:**
References:
Reported By: Saurabh B294b21aa – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅Join Our Cyber World:
- MassDNS for large-scale DNS resolution:
