Subdomain Takeover Vulnerability: A Guide on

Let us take learn more about the subdomain takeover vulnerability issue with the support of our Server management support services at Bobcares.

What is a subdomain takeover vulnerability?

This can occur when the subdomain’s owner forgets to renew it, or when they are not using the service connected with the subdomain but neglect to delete the DNS record that leads to it.

The attacker can take advantage of this vulnerability by creating an account with the same name as the abandoned service or resource and then seizing control of the subdomain by redirecting it to their own malicious server.

This gives them the ability to intercept communications intended for the original service or resource, possibly stealing critical information or launching other attacks.

How to prevent subdomain takeover vulnerabilities?

To avoid subdomain takeover vulnerabilities, it is critical to audit and monitor DNS records on a regular basis to ensure that they are up to date and accurate.

Erase the DNS records for subdomains not in use. And monitor any active subdomains for any suspicious behavior.

To prevent against DNS spoofing and man-in-the-middle attacks, it is better to use security such as DNSSEC and HTTPS.

Situations that make subdomain takeover possible

Below given are some of the common reasons to trigger the subdomain takeover vulnerability.

1. The impacted subdomain’s CNAME record leads to a domain that an attacker can claim.
2. The A record links to an IP address that an attacker can register.
3. A subdomain takeover might pose a number of risks:

   a: Bypassing CSRF protection
   b: Phishing
   c: Leak of OAuth 2.0 Tokens
   d: Bypass Content Security Policy

Checking Dig for Potential Subdomain Takeover Vulnerabilities

With all of that data, we should be able to confirm that a domain is not affected by a potential subdomain takeover. The steps are as follows to check the subdomain takeover vulnerability:

1. Firstly, to check the A records for a domain, use the command “dig a”. If there is an unassigned IP address, the domain may be at risk of subdomain takeover.

   This means that an attacker could potentially register the address.
2. After that, to verify the domain’s CNAME record, use “dig cname”. If the CNAME records lead to a domain that cannot be resolved, an attacker could be able to seize possession of this domain.
3. For example, whether the alias leads to a domain that may be registered or a non existent Amazon AWS S3 website bucket. The attacker may then be able to set up an S3 bucket and reuse the name.

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Conclusion

To sum up we have now seen more on subdomain takeover vulnerability and how to keep security systems rigid with the support of our tech team.