CVE-2002-2097 in MaraDNS
Summary
by MITRE
The compression code in MaraDNS before 0.9.01 allows remote attackers to cause a denial of service via crafted DNS packets.
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Analysis
by VulDB Data Team • 06/28/2021
The vulnerability described in CVE-2002-2097 affects MaraDNS versions prior to 0.9.01 and represents a denial of service flaw within the DNS compression handling mechanism. This issue specifically targets the compression code implementation that processes DNS packets, creating a condition where maliciously crafted packets can trigger unexpected behavior in the DNS server software. The vulnerability operates at the network protocol level where DNS compression is utilized to reduce packet size by replacing repeated domain names with pointers to their first occurrence, a standard practice in DNS implementations.
The technical flaw stems from insufficient input validation within the compression code that fails to properly handle malformed or specially crafted DNS packets containing invalid compression pointers or recursive references. When the MaraDNS server processes these malformed packets, the compression algorithm encounters unexpected data structures that cause the software to enter an undefined state or crash. This behavior aligns with CWE-129, which describes improper validation of input ranges, and CWE-674, which covers uncontrolled recursion in software. The vulnerability demonstrates a classic buffer over-read or pointer manipulation issue where the compression code does not adequately verify the integrity of compression pointers before dereferencing them.
From an operational perspective, this vulnerability presents a significant risk to DNS infrastructure as remote attackers can exploit it to cause service disruption without requiring authentication or elevated privileges. The denial of service impact means that legitimate DNS queries may be unable to process successfully, potentially affecting network availability for all users relying on the affected DNS server. Attackers can craft packets with malicious compression pointers that cause the server to loop indefinitely or consume excessive system resources, leading to complete service unavailability. This vulnerability directly maps to attack techniques found in the MITRE ATT&CK framework under T1499, which covers network denial of service attacks, and T1595, which covers network sniffing and data injection techniques.
The mitigation strategies for this vulnerability involve upgrading to MaraDNS version 0.9.01 or later where the compression code has been properly hardened against malformed inputs. System administrators should implement network monitoring to detect unusual DNS traffic patterns that might indicate exploitation attempts, and consider deploying intrusion detection systems that can identify malformed DNS packets. Additionally, implementing rate limiting and connection tracking mechanisms can help reduce the impact of potential attacks while the software upgrade is being deployed. Organizations should also verify that their DNS server configurations do not accept packets from untrusted sources and maintain regular patch management procedures to ensure all DNS infrastructure remains protected against known vulnerabilities. The fix implemented in version 0.9.01 likely includes enhanced input validation, proper bounds checking for compression pointers, and more robust error handling within the DNS parsing code to prevent the exploitation scenario described in the vulnerability.