Zombie DNS Record
A "Zombie DNS record" is essentially synonymous with a "dangling," "stale," or "orphaned" DNS record. It refers to a DNS entry that continues to exist and resolve, even though it points to a resource (like a website or server) that is no longer active, available, or under the control of its original owner.
How it Can Lead to a Subdomain Takeover:
The mechanism by which a zombie DNS record leads to a subdomain takeover is identical to that of other dangling records:
Resource Decommissioning or Expiration: A company might shut down a service, migrate it to a new platform, or let a domain name expire without updating or removing the associated DNS records.
Zombie DNS Record Persists: The DNS record remains in the DNS zone file, even though the resource it points to no longer exists or is unclaimed.
Attacker Identification: A malicious actor discovers this zombie DNS record and recognizes the opportunity for exploitation.
Resource Recreation: The attacker creates a new resource on the same platform or with a configuration similar to the original.
Subdomain Takeover: Since the zombie DNS record is still active, it inadvertently directs traffic to the attacker's newly created resource.
Malicious Activity: The attacker gains control of the subdomain and can use it for phishing, malware distribution, or traffic redirection.
Key Points:
Zombie DNS records pose a severe security threat as they can facilitate subdomain takeovers.
Regular DNS audits and prompt cleanup of unused or outdated records are crucial for preventing such attacks.
CNAME records are particularly vulnerable as they directly point to other domains or hostnames, making them easy targets for takeover if the target resource becomes unclaimed.
Organizations must prioritize proper DNS hygiene to avoid the potential consequences of subdomain takeovers, including data breaches, financial loss, and damage to brand reputation.
Remember: The term "zombie" emphasizes that the DNS record, though technically still "alive" in the DNS system, points to a "dead" or defunct resource, creating a security loophole that attackers can exploit.
ThreatNG employs a proactive and comprehensive strategy to identify and mitigate vulnerabilities that could lead to subdomain takeovers:
Deep Discovery and Assessment:
Domain Intelligence:
DNS Intelligence: Continuously scans DNS records, meticulously examining CNAME, A, and other record types for misconfigurations or inconsistencies that might signal potential takeover opportunities.
Subdomain Intelligence: Thoroughly maps and assesses all active and inactive subdomains, identifying any exhibiting vulnerabilities or signs of neglect.
Certificate Intelligence: Monitors SSL certificates for expiration, mismatches, or other irregularities that could leave subdomains open to exploitation.
Cloud and SaaS Exposure:
Sanctioned/Unsanctioned Cloud Services: This tool discovers the organization's cloud resources, pinpointing any unmanaged or forgotten services with associated DNS records.
Cloud Service Impersonations: This feature detects attempts to impersonate legitimate cloud services, which could be a precursor to a subdomain takeover.
Exposed API Discovery & Exposed Development Environment Discovery:
Uncovers publicly accessible APIs and development environments that might inadvertently expose sensitive subdomain information or provide an entry point for attackers.
Technology Stack:
Identifies the organization's technologies and services, allowing for targeted assessment of its known vulnerabilities and potential misconfigurations that could contribute to subdomain takeover susceptibility.
Continuous Monitoring and Alerting:
Continuous monitoring of all discovered assets and configurations for any changes or anomalies that could indicate a heightened risk of subdomain takeover.
Prompt alerts to security teams when vulnerabilities or suspicious activities are detected, enabling swift response and remediation.
Integration with existing security solutions to automate workflows and facilitate efficient incident response.
Intelligence Enrichment and Contextualization:
Dark Web Presence:
Monitors underground forums and marketplaces for discussions or evidence of malicious actors targeting the organization's subdomains.
Identifies any compromised credentials or sensitive data leaks that could be leveraged in a subdomain takeover attempt.
Compromised Credentials:
Tracks data breaches and credential leaks that could expose user accounts with access to DNS management or cloud services, increasing the risk of unauthorized subdomain changes.
Known Vulnerabilities:
Maintaining an up-to-date database of vulnerabilities affecting various technologies and services the organization uses enables proactive identification and remediation of weaknesses that could be exploited in a subdomain takeover.
Complementary Solutions Integration:
ThreatNG seamlessly integrates with other security tools to enhance its subdomain takeover prevention capabilities:
Web Application Firewalls (WAFs): WAFs can be configured to block traffic to or from vulnerable subdomains, mitigating potential attacks.
Vulnerability Scanners: Regular vulnerability scans can help identify and address subdomain weaknesses that could be exploited.
Security Information and Event Management (SIEM) Systems: SIEMs can collect and correlate data from ThreatNG and other security tools to provide a holistic view of the organization's security posture and facilitate incident response.
Examples:
Dangling CNAME Record: ThreatNG's DNS Intelligence module detects a CNAME record pointing to a decommissioned third-party service. The Subdomain Takeover Susceptibility assessment flags this as a high-risk vulnerability, prompting immediate action to remove the record or reconfigure the subdomain.
Exposed Development Environment: The Discovery capability identifies a staging server accessible from the internet, potentially exposing sensitive subdomain information. ThreatNG alerts the security team, allowing them to secure the environment and prevent unauthorized access.
Leaked Credentials on the Dark Web: ThreatNG's Dark Web Presence module uncovers leaked credentials for users accessing the organization's DNS management system. The security team is promptly alerted, enabling them to reset the compromised credentials and prevent a potential subdomain takeover.
ThreatNG's comprehensive capabilities and proactive approach make it a powerful tool for identifying and mitigating subdomain takeover susceptibility. By combining in-depth discovery, continuous monitoring, and intelligence enrichment with seamless integration with complementary solutions, ThreatNG empowers organizations to protect their critical assets and maintain a robust security posture in the face of evolving threats.
