CVE-2015-1868 in PowerDNS Recursor
Summary
by MITRE
The label decompression functionality in PowerDNS Recursor 3.5.x, 3.6.x before 3.6.3, and 3.7.x before 3.7.2 and Authoritative (Auth) Server 3.2.x, 3.3.x before 3.3.2, and 3.4.x before 3.4.4 allows remote attackers to cause a denial of service (CPU consumption or crash) via a request with a name that refers to itself.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 11/29/2024
The vulnerability identified as CVE-2015-1868 represents a critical denial of service flaw within PowerDNS Recursor and Authoritative Server implementations. This issue stems from improper handling of label decompression operations when processing DNS queries containing self-referential names. The affected versions include PowerDNS Recursor 3.5.x, 3.6.x before 3.6.3, and 3.7.x before 3.7.2, along with Authoritative Server 3.2.x, 3.3.x before 3.3.2, and 3.4.x before 3.4.4. The flaw manifests when a remote attacker crafts a malicious DNS query that references itself within the domain name structure, triggering problematic decompression routines that consume excessive CPU resources or cause application crashes.
The technical implementation of this vulnerability resides in the DNS label decompression algorithm used by PowerDNS components. When processing DNS queries with self-referential names, the decompression logic enters into infinite or excessively long loops, causing the system to consume all available CPU cycles or exhaust memory resources. This behavior directly maps to CWE-835, which describes the weakness of an infinite loop or infinite recursion in software implementations. The vulnerability operates at the protocol processing layer where DNS name compression and decompression occur, making it particularly dangerous as it can be triggered by any valid DNS query without requiring authentication or special privileges. The attack vector is entirely remote and can be executed through standard DNS query mechanisms, making it highly exploitable in networked environments.
The operational impact of CVE-2015-1868 extends beyond simple service disruption to potentially compromise entire DNS infrastructure availability. When exploited, the vulnerability can cause sustained CPU exhaustion that prevents legitimate DNS queries from being processed, effectively rendering the affected DNS server incapable of providing normal service to clients. Additionally, the system crashes that occur during exploitation can result in complete service outages requiring manual intervention and system restarts. This type of denial of service attack directly aligns with ATT&CK technique T1499.004, which covers network denial of service attacks targeting DNS services. The vulnerability affects both authoritative and recursive DNS servers, making it particularly dangerous for organizations that rely on PowerDNS for critical infrastructure services. The impact is amplified in environments where DNS servers handle high volumes of traffic, as the resource exhaustion can quickly overwhelm system capabilities and affect multiple dependent services.
Organizations affected by this vulnerability should immediately apply patches released by PowerDNS for versions 3.6.3, 3.7.2, 3.3.2, and 3.4.4 respectively, which contain fixes for the label decompression logic. Network administrators should implement monitoring solutions to detect unusual CPU consumption patterns or service disruptions that may indicate exploitation attempts. Additional mitigations include implementing DNS query rate limiting, deploying intrusion detection systems that can identify malformed DNS queries, and establishing redundant DNS infrastructure to maintain service availability during potential attacks. The fix addresses the root cause by implementing proper bounds checking and loop termination conditions in the decompression routines, preventing infinite recursion scenarios that were previously possible with self-referential DNS names.