CVE-2003-0430 in Ethereal
Summary
by MITRE
The SPNEGO dissector in Ethereal 0.9.12 and earlier allows remote attackers to cause a denial of service (crash) via an invalid ASN.1 value.
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Analysis
by VulDB Data Team • 05/28/2019
The vulnerability described in CVE-2003-0430 represents a critical denial of service flaw within the SPNEGO dissector component of Ethereal network protocol analyzer version 0.9.12 and earlier. This issue arises from inadequate input validation mechanisms within the application's handling of ASN.1 encoded data structures, specifically those related to the Simple and Protected GSSAPI Negotiation Mechanism. The vulnerability manifests when the dissector encounters malformed ASN.1 values during network traffic analysis, causing the application to crash and terminate unexpectedly. This type of flaw falls under the category of improper input validation as classified by CWE-20, which encompasses weaknesses resulting from insufficient validation of data received from external sources.
The technical exploitation of this vulnerability requires an attacker to craft and transmit specially formatted network packets containing invalid ASN.1 values to a system running the vulnerable Ethereal version. When the SPNEGO dissector attempts to parse these malformed values, the application fails to properly handle the unexpected data structure, leading to a segmentation fault or similar crash condition. This behavior aligns with the ATT&CK technique T1499.004 for network denial of service attacks, where adversaries leverage application-level flaws to disrupt services. The vulnerability demonstrates a classic buffer over-read or improper state handling scenario where the dissector does not implement robust error handling for malformed ASN.1 sequences, causing the program to execute invalid memory access patterns.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited by remote attackers without requiring authentication or privileged access. Any user or system that processes network traffic through the vulnerable Ethereal version becomes susceptible to this attack vector, potentially affecting network monitoring operations, security analysis workflows, and incident response activities. The crash condition can result in complete loss of network analysis capabilities for the affected system, forcing administrators to restart the application and potentially lose valuable network traffic data. This vulnerability particularly impacts organizations relying on Ethereal for network security monitoring and forensic analysis, as the application's instability can compromise security operations and create windows of vulnerability during restart periods.
Mitigation strategies for CVE-2003-0430 involve immediate patching of the Ethereal application to version 0.9.13 or later, which contains corrected ASN.1 parsing logic and improved input validation mechanisms. Organizations should also implement network segmentation and access controls to limit exposure of vulnerable systems, while monitoring for suspicious network traffic patterns that might indicate exploitation attempts. Additional defensive measures include deploying network intrusion detection systems that can identify malformed ASN.1 traffic patterns and implementing application whitelisting policies to restrict execution of untrusted network analysis tools. The fix implemented in subsequent versions addresses the underlying CWE-20 weakness by introducing proper boundary checks and error handling for ASN.1 value processing, preventing the dissector from crashing when encountering malformed input data.