CVE-2000-0020 in DNS PRO
Summary
by MITRE
DNS PRO allows remote attackers to conduct a denial of service via a large number of connections.
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Analysis
by VulDB Data Team • 04/20/2026
The vulnerability described in CVE-2000-0020 affects DNS PRO services and represents a classic denial of service attack vector that exploits the protocol's handling of multiple concurrent connections. This weakness allows remote attackers to overwhelm the target system by establishing a large number of simultaneous connections, effectively consuming available resources and rendering legitimate service requests impossible to process. The issue stems from inadequate connection management and resource allocation mechanisms within the DNS PRO implementation, creating a scenario where the system cannot properly handle legitimate traffic while under attack.
From a technical perspective, this vulnerability operates at the network protocol level and demonstrates poor resource exhaustion handling within the DNS service implementation. The flaw allows attackers to establish numerous connections without proper rate limiting or connection pooling controls, leading to a situation where the system's available file descriptors, memory allocations, or processing capacity becomes saturated. This type of vulnerability aligns with CWE-400, which categorizes unchecked resource allocation as a fundamental weakness in software design that can lead to resource exhaustion attacks. The attack vector specifically targets the service's ability to manage concurrent connections, making it a prime example of a resource depletion attack that can be executed remotely without requiring privileged access.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the availability of critical network infrastructure. When DNS services become unavailable due to connection exhaustion, it can cascade into broader network outages affecting multiple systems that depend on DNS resolution for their operations. Organizations relying on DNS PRO services face significant risk during such attacks, as they may experience complete service unavailability while attackers maintain their connection flood without detection or mitigation. This vulnerability particularly affects systems where DNS services are not properly hardened against connection-based attacks, making it a common target for attackers seeking to disrupt network operations.
Effective mitigation strategies for this vulnerability require implementing connection rate limiting, connection pooling mechanisms, and proper resource monitoring to detect and prevent excessive connection attempts. Network administrators should deploy firewall rules and access control lists to limit the number of connections from individual IP addresses, while also implementing proper logging and alerting mechanisms to detect unusual connection patterns. The solution approach aligns with ATT&CK technique T1498, which describes network denial of service attacks that leverage resource exhaustion to disrupt services. Organizations should also consider implementing intrusion detection systems that can identify and block connection flood patterns, along with proper capacity planning to ensure systems can handle legitimate traffic loads while maintaining adequate buffer capacity against attack scenarios.