CVE-2005-0037 in DNRD
Summary
by MITRE
The DNS implementation of DNRD before 2.10 allows remote attackers to cause a denial of service via a compressed DNS packet with a label length byte with an incorrect offset, which could trigger an infinite loop.
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Analysis
by VulDB Data Team • 07/09/2024
The vulnerability described in CVE-2005-0037 affects the DNS implementation within DNRD software versions prior to 2.10, representing a critical denial of service weakness that could be exploited by remote attackers to disrupt network services. This flaw resides in the handling of compressed DNS packets, specifically targeting the label length byte processing mechanism that is fundamental to DNS protocol operations. The vulnerability demonstrates a classic example of improper input validation where the system fails to properly validate the offset values within compressed DNS labels, creating a condition that can be manipulated to cause system instability.
The technical flaw manifests when DNRD encounters a specially crafted compressed DNS packet containing a label length byte with an incorrect offset value. This incorrect offset causes the DNS resolver to enter an infinite loop during packet processing, as the system attempts to follow a malformed pointer that leads back to itself or creates a recursive reference pattern. The issue stems from the lack of proper bounds checking and validation of pointer offsets within the DNS compression algorithm, which is a well-documented weakness categorized under CWE-129 Input Validation and CWE-691 Uncontrolled Recursion. The vulnerability is particularly dangerous because it can be triggered through normal DNS query processing without requiring authentication or special privileges, making it an attractive target for attackers seeking to disrupt DNS services.
The operational impact of this vulnerability extends beyond simple service disruption, as it can affect the availability of critical network infrastructure that relies on DNS resolution. When exploited, the infinite loop consumes system resources continuously, potentially leading to system crashes, memory exhaustion, or complete service unavailability for legitimate users. This type of denial of service attack directly impacts the availability component of the CIA triad and can be classified under the MITRE ATT&CK technique T1499.004 for Network Denial of Service, where attackers leverage protocol implementation flaws to exhaust system resources. Organizations relying on DNRD for DNS services would experience significant downtime and potential service degradation, particularly in environments where DNS availability is critical for business operations or where the software serves as a primary DNS resolver.
Mitigation strategies for this vulnerability require immediate patching of affected DNRD installations to version 2.10 or later, which contains the necessary fixes for proper offset validation and bounds checking. System administrators should also implement network monitoring to detect unusual DNS traffic patterns that might indicate exploitation attempts, and consider implementing rate limiting or traffic filtering mechanisms to prevent exploitation. The fix typically involves adding proper validation checks for pointer offsets within compressed DNS labels, ensuring that any offset values fall within acceptable ranges and do not create recursive or circular references. Additionally, organizations should conduct regular vulnerability assessments of their DNS infrastructure and maintain up-to-date security patches to prevent similar issues from arising in other DNS implementations that may share similar architectural weaknesses.