CVE-2011-0520 in MaraDNS
Summary
by MITRE
The compress_add_dlabel_points function in dns/Compress.c in MaraDNS 1.4.03, 1.4.05, and probably other versions allows remote attackers to cause a denial of service (segmentation fault) and possibly execute arbitrary code via a long DNS hostname with a large number of labels, which triggers a heap-based buffer overflow.
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Analysis
by VulDB Data Team • 10/13/2021
The vulnerability identified as CVE-2011-0520 affects MaraDNS versions 1.4.03 and 1.4.05, presenting a critical security flaw in the DNS compression handling mechanism. This issue resides within the compress_add_dlabel_points function located in the dns/Compress.c source file, which is responsible for managing DNS label compression during packet processing. The vulnerability stems from inadequate input validation and buffer management when processing DNS hostnames containing an excessive number of labels, creating a condition where maliciously crafted DNS queries can trigger unexpected behavior in the application's memory management.
The technical exploitation of this vulnerability occurs through a heap-based buffer overflow attack that exploits the insufficient bounds checking in the DNS label processing code. When a remote attacker submits a DNS query containing a hostname with an excessive number of labels, the compress_add_dlabel_points function fails to properly validate the input length before attempting to process the data. This failure results in memory corruption that manifests as a segmentation fault, effectively causing a denial of service condition that crashes the MaraDNS process. However, the vulnerability's potential extends beyond simple service disruption, as the heap corruption may provide opportunities for arbitrary code execution, making this a particularly dangerous flaw in network services.
The operational impact of this vulnerability is significant for organizations relying on MaraDNS as their authoritative or recursive DNS server. A successful attack can lead to complete service unavailability, disrupting DNS resolution for all clients dependent on the affected server. The potential for remote code execution amplifies the risk, as attackers could gain control over the DNS server and potentially use it as a pivot point for further attacks within the network infrastructure. This vulnerability directly impacts the availability and integrity of DNS services, which form the foundation of internet connectivity and network operations, making it a critical concern for system administrators and security teams.
Mitigation strategies for CVE-2011-0520 should prioritize immediate patching of affected MaraDNS versions to the latest stable releases that contain the necessary fixes for the buffer overflow vulnerability. Organizations should implement network-level protections such as DNS query rate limiting and input validation at the network perimeter to prevent malicious queries from reaching the vulnerable server. Additionally, monitoring for unusual DNS query patterns and implementing intrusion detection systems can help identify potential exploitation attempts. The vulnerability aligns with CWE-121, heap-based buffer overflow, and represents a technique commonly associated with attack vectors in the MITRE ATT&CK framework under the T1499 category for network denial of service. Regular security assessments and vulnerability scanning should be conducted to ensure all DNS server implementations remain protected against similar memory corruption issues.