CVE-2020-5591 in DNS
Summary
by MITRE
XACK DNS 1.11.0 to 1.11.4, 1.10.0 to 1.10.8, 1.8.0 to 1.8.23, 1.7.0 to 1.7.18, and versions before 1.7.0 allow remote attackers to cause a denial of service condition resulting in degradation of the recursive resolver's performance or compromising the recursive resolver as a reflector in a reflection attack.
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Analysis
by VulDB Data Team • 06/06/2020
The vulnerability identified as CVE-2020-5591 affects XACK DNS server versions across multiple release branches including 1.11.0 through 1.11.4, 1.10.0 through 1.10.8, 1.8.0 through 1.8.23, 1.7.0 through 1.7.18, and all versions prior to 1.7.0. This flaw represents a significant security concern that can be exploited by remote attackers to compromise the integrity and availability of DNS infrastructure. The vulnerability manifests as a denial of service condition that can severely impact recursive DNS resolver performance or potentially transform the affected server into a reflector within reflection attacks, making it a critical concern for network administrators and security professionals managing DNS services.
The technical nature of this vulnerability stems from insufficient input validation and processing mechanisms within the XACK DNS implementation. Attackers can craft malicious DNS queries that exploit weaknesses in the recursive resolver's handling of specific packet formats or query structures. These malformed or specially crafted requests can cause the resolver to consume excessive computational resources, leading to performance degradation that manifests as slow response times or complete service unavailability. The vulnerability's impact extends beyond simple denial of service as it can also enable attackers to leverage the compromised server as a reflector in distributed reflection attacks, where the server amplifies traffic directed at victim targets. This dual nature of the vulnerability makes it particularly dangerous in network environments where DNS servers serve as critical infrastructure components.
The operational impact of CVE-2020-5591 can be severe for organizations relying on affected XACK DNS versions. Performance degradation may result in extended DNS resolution times, impacting user experience and potentially causing cascading failures in applications that depend on timely DNS resolution. When the vulnerability is exploited to create a reflector, the affected DNS server becomes a vector for launching larger-scale attacks against other network targets, potentially violating the organization's network security policies and exposing it to liability. Organizations may experience increased network traffic, system resource exhaustion, and potential service interruptions that can affect business operations and customer satisfaction. The vulnerability also represents a risk to the broader DNS ecosystem, as compromised servers can contribute to amplification attacks that target other networks and services.
Mitigation strategies for CVE-2020-5591 should prioritize immediate patching of affected XACK DNS installations to versions that address the identified vulnerabilities. Organizations should implement network-level protections such as rate limiting and query filtering to reduce the impact of malicious traffic patterns. Security teams should monitor DNS server performance metrics closely and establish alerting mechanisms for unusual traffic patterns or resource consumption spikes that may indicate exploitation attempts. The implementation of DNS security extensions including DNSSEC can provide additional protection layers against certain types of attacks targeting DNS infrastructure. Network administrators should also consider implementing access controls and firewall rules to restrict DNS query sources and limit exposure to potentially malicious traffic. According to CWE standards, this vulnerability aligns with CWE-400, which addresses improper resource management, and may also relate to CWE-121, concerning stack-based buffer overflow conditions. From an ATT&CK perspective, this vulnerability maps to techniques involving denial of service and reflection attacks, specifically T1498.1 for network denial of service and T1498.2 for reflection attacks, making it a significant concern for organizations implementing comprehensive threat detection and response strategies.