CVE-2000-0333 in tcpdump
Summary
by MITRE
tcpdump, Ethereal, and other sniffer packages allow remote attackers to cause a denial of service via malformed DNS packets in which a jump offset refers to itself, which causes tcpdump to enter an infinite loop while decompressing the packet.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 12/12/2024
The vulnerability identified as CVE-2000-0333 represents a critical denial of service flaw affecting tcpdump and related network sniffer applications including Ethereal. This issue stems from inadequate input validation during DNS packet processing, specifically when handling compressed DNS names within network traffic captures. The flaw manifests when a DNS packet contains a malformed jump offset that references itself, creating a circular reference condition that leads to infinite loop execution during packet decompression operations.
The technical implementation of this vulnerability exploits the DNS name compression mechanism used in internet protocols to reduce packet size. DNS names are typically compressed using pointers that reference previously encountered name labels within the same packet. When a jump offset points to an address that references back to itself, the decompression routine enters an infinite loop as it continuously follows the same pointer without reaching a terminating condition. This condition affects tcpdump's packet parsing logic and other similar network analysis tools that rely on standard DNS packet parsing routines.
From an operational perspective, this vulnerability presents a significant threat to network monitoring and security operations. Attackers can exploit this flaw by crafting malicious DNS packets and transmitting them to systems running tcpdump or compatible sniffer software. The resulting denial of service impacts network administrators who depend on these tools for traffic analysis, intrusion detection, and network troubleshooting. The infinite loop consumes system resources continuously, potentially leading to system crashes or unavailability of network monitoring services that could compromise broader security operations.
This vulnerability aligns with CWE-835, which describes the weakness of an infinite loop in software applications, and relates to the broader category of input validation failures in network protocol implementations. The attack vector follows the ATT&CK technique T1498, specifically targeting network denial of service through malformed packet injection. The vulnerability demonstrates the critical importance of robust input validation in network protocol parsing libraries and highlights the potential for seemingly benign network traffic to cause catastrophic system failures.
Mitigation strategies include implementing proper bounds checking and circular reference detection in DNS decompression routines, applying protocol-specific timeouts during packet processing, and deploying network security appliances that can filter malformed DNS traffic before it reaches vulnerable systems. System administrators should also maintain updated versions of network monitoring tools, as this vulnerability was addressed through patches that introduced proper loop detection mechanisms and enhanced input validation. Additionally, network segmentation and traffic filtering can provide defense-in-depth measures to prevent exploitation of this class of vulnerability.