Hackers are increasingly exploiting Dangling DNS records to take over subdomains, posing serious security risks. This occurs when organizations fail to properly update DNS records after decommissioning services or cloud resources. For instance, attackers can hijack abandoned subdomains, such as those previously used for customer support, by registering the expired service under the same name. If a company’s DNS entry points to an inactive or non-existent service, it becomes vulnerable to these attacks.
In a typical Dangling DNS attack, attackers exploit misconfigured CNAME, MX, NS, or A records to redirect traffic to malicious services. The threat becomes even more pronounced in cloud environments, where leftover DNS entries for deleted resources can be exploited. For example, attackers can register cloud services under a previously used subdomain, redirecting traffic to malicious servers. Security researchers have identified over 150 such instances where organizations failed to update their DNS records, leaving them exposed to attack.
The consequences of Dangling DNS attacks go beyond defacing websites or stealing credentials. Attackers can inject malicious code into software update channels, hijack critical cloud resources, or even plant persistent backdoors. Such exploits can severely compromise the security of the affected organization and its customers. For instance, malicious actors could alter supply chain updates, leading to compromised software and systems in the broader network.
Security firms like SentinelOne have identified over 1,250 cases of subdomain takeover risks in the past year, particularly involving cloud resources. The findings underscore the need for organizations to implement strict DNS management practices. Vigilant monitoring and timely removal of outdated DNS records are essential to prevent these attacks. With the increasing sophistication of these threats, organizations must ensure their DNS configurations are regularly updated and securely decommissioned.
