CVE-2005-2315 in DNRD
Summary
by MITRE
Buffer overflow in Domain Name Relay Daemon (DNRD) before 2.19.1 allows remote attackers to execute arbitrary code via a large number of large DNS packets with the Z and QR flags cleared.
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Analysis
by VulDB Data Team • 08/04/2019
The Domain Name Relay Daemon (DNRD) buffer overflow vulnerability represents a critical security flaw that existed in versions prior to 2.19.1, enabling remote code execution through carefully crafted DNS packet manipulation. This vulnerability falls under the CWE-121 buffer overflow category, specifically manifesting as a classic stack-based buffer overflow that occurs when the daemon processes malformed DNS queries without proper input validation. The flaw exploits the daemon's insufficient bounds checking mechanisms when handling DNS packets that contain unusually large data payloads while simultaneously having both the Z flag and QR flag cleared. The Z flag typically indicates reserved bits in DNS packets, while the QR flag distinguishes between queries and responses, making the combination of these cleared flags particularly suspicious and exploitable.
The technical exploitation of this vulnerability requires attackers to send a sequence of DNS packets that exceed the allocated buffer space within the DNRD process memory. When the daemon attempts to process these oversized packets, the data overflows into adjacent memory locations, potentially overwriting critical program execution structures such as return addresses or function pointers. This memory corruption allows attackers to redirect program execution flow to malicious code injected into the buffer space, effectively achieving remote code execution privileges on the affected system. The vulnerability's remote nature means that attackers can exploit it from any network location without requiring local access, making it particularly dangerous in networked environments where DNS services are exposed to external traffic.
The operational impact of this vulnerability extends beyond simple remote code execution, as it can lead to complete system compromise and unauthorized access to sensitive network resources. Organizations relying on DNRD for DNS relay services face significant risks including data breaches, service disruption, and potential lateral movement within their network infrastructure. The vulnerability's exploitation can result in persistent backdoor access, making it difficult for security teams to detect and remediate the compromise. Additionally, the widespread use of DNS relay services in enterprise environments means that a single vulnerable DNRD instance can potentially affect multiple network segments and applications that depend on proper DNS resolution services.
Security mitigations for this vulnerability primarily involve immediate patching of DNRD installations to version 2.19.1 or later, which includes proper input validation and buffer size enforcement mechanisms. Network administrators should implement additional defensive measures such as DNS query filtering to detect and block suspicious packet patterns, particularly those with cleared Z and QR flags. The implementation of proper network segmentation and access controls can help limit the potential impact of exploitation, while continuous monitoring of DNS traffic for anomalous patterns provides early detection capabilities. Organizations should also consider implementing intrusion detection systems with signature-based detection for known exploit patterns related to this vulnerability, aligning with ATT&CK technique T1071.004 for application layer protocol tunneling and T1203 for exploitation for privilege escalation. Regular security assessments and vulnerability scanning should be conducted to identify other potentially affected services, as similar buffer overflow vulnerabilities may exist in other DNS-related applications within the network infrastructure.