CVE-2006-2069 in PowerDNS
Summary
by MITRE
The recursor in PowerDNS before 3.0.1 allows remote attackers to cause a denial of service (application crash) via malformed EDNS0 packets.
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Analysis
by VulDB Data Team • 07/29/2019
The vulnerability identified as CVE-2006-2069 represents a critical denial of service weakness in PowerDNS recursor versions prior to 3.0.1. This flaw specifically targets the handling of EDNS0 (Extension Mechanisms for DNS) packets, which are essential components of modern DNS infrastructure that enable extended functionality beyond the original DNS protocol specification. The vulnerability arises from insufficient input validation within the recursor's packet processing logic, creating a scenario where maliciously crafted EDNS0 packets can trigger application instability.
The technical exploitation of this vulnerability occurs when a remote attacker sends malformed EDNS0 packets to a vulnerable PowerDNS recursor instance. These packets contain invalid or unexpected data structures that the recursor fails to properly handle during parsing and processing. The flaw manifests as an application crash or daemon termination, effectively rendering the DNS resolution service unavailable to legitimate users. This type of vulnerability falls under CWE-129, which addresses improper validation of array indices, and represents a classic buffer over-read or improper input sanitization issue that can be exploited to cause system instability.
The operational impact of CVE-2006-2069 extends beyond simple service disruption, as DNS infrastructure forms the backbone of internet connectivity for countless applications and services. When a recursor becomes unavailable due to this vulnerability, it can cascade into broader network outages affecting organizations that depend on DNS resolution for their operations. The vulnerability aligns with ATT&CK technique T1498, which describes denial of service attacks targeting network infrastructure, and specifically maps to the sub-technique of application or system exploitation. Organizations running affected versions of PowerDNS are particularly vulnerable since the flaw can be exploited without authentication, making it an attractive target for automated attacks or opportunistic exploitation.
Mitigation strategies for this vulnerability require immediate patching of affected PowerDNS installations to version 3.0.1 or later, which includes proper input validation for EDNS0 packet handling. Network administrators should also implement monitoring solutions to detect unusual traffic patterns that might indicate exploitation attempts, while configuring firewalls to limit DNS query volumes from suspicious sources. The fix implemented in PowerDNS 3.0.1 demonstrates proper defensive programming practices by incorporating robust input validation and error handling mechanisms for EDNS0 packet processing, aligning with security best practices outlined in the OWASP Top Ten and NIST cybersecurity guidelines for input validation and error handling. Organizations should also consider implementing DNS traffic filtering rules that can identify and block malformed EDNS0 packets at network boundaries to provide additional defense in depth.