CVE-2007-6341 in Net Dns
Summary
by MITRE
Net/DNS/RR/A.pm in Net::DNS 0.60 build 654, as used in packages such as SpamAssassin and OTRS, allows remote attackers to cause a denial of service (program "croak") via a crafted DNS response.
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Analysis
by VulDB Data Team • 12/27/2024
The vulnerability identified as CVE-2007-6341 represents a critical denial of service flaw within the Net::DNS Perl module version 0.60 build 654 and its subsequent distributions. This vulnerability specifically affects the Net/DNS/RR/A.pm component which handles DNS A record processing, making it particularly dangerous given the widespread adoption of Net::DNS in email filtering systems like SpamAssassin and help desk platforms such as OTRS. The flaw manifests when these applications process malformed DNS responses containing specially crafted A records that trigger an unhandled exception in the Perl interpreter.
The technical mechanism behind this vulnerability involves the improper handling of malformed DNS A records during the parsing process within the Net::DNS module. When the module encounters a crafted DNS response containing invalid or unexpected data in the A record section, it fails to properly validate the input before attempting to process it. This leads to a program termination through the "croak" function, which is Perl's standard mechanism for throwing fatal errors. The vulnerability stems from inadequate input validation and error handling practices within the DNS record parsing code, particularly in how the module handles malformed data structures that should be gracefully rejected or properly parsed.
The operational impact of this vulnerability extends far beyond simple service disruption, as it affects critical infrastructure components that rely on DNS resolution for their operation. When exploited, the vulnerability can cause SpamAssassin to crash and restart repeatedly, leading to email delivery delays and potential complete email service outages. Similarly, OTRS systems may experience service interruptions that impact customer support operations and business continuity. The attack vector is particularly concerning because it requires only a single malicious DNS response to trigger the vulnerability, making it easy to exploit in various network environments. This vulnerability also aligns with ATT&CK technique T1499.004 for network denial of service attacks and CWE-20 for improper input validation, highlighting the fundamental security weakness in the input sanitization process.
Mitigation strategies for CVE-2007-6341 involve immediate patching of the affected Net::DNS module to version 0.61 or later, which contains the necessary fixes for proper input validation. Organizations should also implement network-level protections such as DNS response validation, rate limiting of DNS queries, and implementing DNS caching solutions that can filter out malformed responses before they reach the vulnerable applications. Additionally, system administrators should consider implementing monitoring solutions that can detect and alert on service restarts or crashes that may indicate exploitation attempts. The vulnerability demonstrates the importance of maintaining up-to-date security libraries and implementing defense-in-depth strategies that protect against both known and unknown vulnerabilities through multiple layers of security controls.