Subdomain takeover is a type of vulnerability that occurs when a subdomain (e.g., blog.example.com) points to a service that no longer exists or is no longer controlled by the domain owner. This allows an attacker to gain control of the subdomain and host their content, potentially leading to phishing attacks, malware distribution, or data theft.

How Subdomain Takeovers Happen

1. DNS Misconfiguration: A subdomain's DNS records might point to a discontinued or removed third-party service (like a cloud hosting provider).

2. Forgotten Resources: Organizations may need to remember old subdomains pointing to external services.

3. Lack of Verification: Some third-party services don't correctly verify subdomain ownership, allowing attackers to claim them.

Why Subdomain Takeovers Are Dangerous

• Damage to Reputation: Attackers can use the subdomain to host malicious content, harming the organization's reputation.

• Phishing Attacks: Attackers can create convincing phishing pages that mimic the legitimate website.

• Malware Distribution: Attackers can distribute malware through the compromised subdomain.

• Data Theft: Attackers can steal user credentials or other sensitive information if the subdomain was previously used for logins or data collection.

How ThreatNG Helps Prevent and Mitigate Subdomain Takeovers

ThreatNG offers a robust set of tools to combat subdomain takeovers:

• Domain Intelligence

• Subdomain Intelligence: ThreatNG actively discovers and analyzes all subdomains associated with an organization, even forgotten or unused ones.

• DNS Intelligence: ThreatNG examines DNS records to identify misconfigurations or subdomains pointing to non-existent services.

• Certificate Intelligence: ThreatNG checks for inconsistencies in SSL/TLS certificates, which could indicate a takeover attempt.

• Continuous Monitoring

• ThreatNG continuously monitors DNS records and subdomains for changes, alerting security teams to suspicious activity or potential takeovers.

• Integration with Other Tools

• Vulnerability Scanners: ThreatNG can integrate with vulnerability scanners to identify weaknesses in web applications hosted on subdomains.

• SIEM: ThreatNG can feed subdomain takeover alerts into a SIEM system for centralized monitoring and incident response.

Examples

• Dangling DNS Record: ThreatNG discovers that blog.example.com points to a discontinued cloud hosting service. An attacker could claim this subdomain and host malicious content. ThreatNG alerts the security team to rectify the DNS record.

• Forgotten Subdomain: ThreatNG identifies an old subdomain (promo.example.com) that is still active but forgotten by the organization. This subdomain could be vulnerable to takeover, so ThreatNG reminds the organization to either remove or secure it properly.

Key Takeaways

• Subdomain takeovers are a severe threat that can damage an organization's reputation and compromise user data.

• ThreatNG provides a comprehensive solution for preventing and mitigating subdomain takeovers through continuous monitoring, DNS analysis, and integration with other security tools.

• Proactive subdomain management and regular security assessments are crucial to minimize the risk of subdomain takeovers.