CVE-2003-0093 in tcpdump
Summary
by MITRE
The RADIUS decoder in tcpdump 3.6.2 and earlier allows remote attackers to cause a denial of service (crash) via an invalid RADIUS packet with a header length field of 0, which causes tcpdump to generate data within an infinite loop.
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Analysis
by VulDB Data Team • 06/28/2021
The vulnerability identified as CVE-2003-0093 represents a critical denial of service flaw within tcpdump's RADIUS packet processing functionality. This issue affects tcpdump versions 3.6.2 and earlier, where the software fails to properly validate RADIUS packet headers before processing them. The vulnerability stems from a lack of input validation in the RADIUS decoder component, which is responsible for parsing and analyzing RADIUS protocol packets that are commonly used for network authentication and accounting purposes. When tcpdump encounters a malformed RADIUS packet with a header length field set to zero, the software's parsing logic becomes trapped in an infinite loop, causing the application to consume excessive system resources and ultimately crash.
The technical implementation of this vulnerability demonstrates a classic buffer over-read and loop control flaw that aligns with CWE-122, which describes buffer overflow conditions in memory management. The flaw occurs because tcpdump's RADIUS decoder does not perform adequate bounds checking on the header length field before attempting to process the packet data. When a RADIUS packet header contains a zero length field, the decoder attempts to read data from the packet in a manner that creates an infinite loop, as the software continues to process what it believes to be valid packet data without proper termination conditions. This behavior is consistent with the ATT&CK technique T1499.004, which involves network denial of service attacks that exploit software vulnerabilities to exhaust system resources.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited by remote attackers to cause persistent denial of service conditions on systems running vulnerable versions of tcpdump. Network administrators who rely on tcpdump for network monitoring and analysis would experience complete loss of monitoring capabilities when an attacker sends a specially crafted RADIUS packet with a zero-length header field. The vulnerability is particularly concerning because RADIUS packets are commonly transmitted across network infrastructure, making the attack surface quite broad. The infinite loop condition consumes CPU cycles and memory resources, potentially affecting not only the tcpdump process but also the overall system performance and availability of network monitoring services.
Mitigation strategies for this vulnerability require immediate patching of tcpdump installations to versions that properly validate RADIUS packet headers before processing them. System administrators should ensure that all network monitoring equipment running tcpdump is updated to the latest stable releases that contain the fix for this specific vulnerability. Additionally, network administrators can implement packet filtering rules at network boundaries to drop RADIUS packets with malformed headers, providing an additional layer of protection. The fix typically involves adding proper validation checks for header length fields and implementing appropriate loop termination conditions within the RADIUS decoder module. Organizations should also consider implementing intrusion detection systems that can identify and alert on anomalous RADIUS packet patterns that may indicate exploitation attempts. This vulnerability highlights the importance of robust input validation and proper error handling in network security tools, as these components are critical for maintaining system stability and preventing exploitation of parsing vulnerabilities.