CVE-2020-15466 in Wireshark
Summary
by MITRE
In Wireshark 3.2.0 to 3.2.4, the GVCP dissector could go into an infinite loop. This was addressed in epan/dissectors/packet-gvcp.c by ensuring that an offset increases in all situations.
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Analysis
by VulDB Data Team • 07/06/2020
The vulnerability identified as CVE-2020-15466 represents a critical denial of service flaw within Wireshark's GVCP dissector functionality. This issue affects Wireshark versions 3.2.0 through 3.2.4, where the General Video Control Protocol dissector fails to properly handle certain packet structures, leading to an infinite loop condition. The GVCP protocol is used for controlling video devices in industrial and surveillance environments, making this vulnerability particularly concerning for network security monitoring systems that rely on Wireshark for packet analysis. The flaw manifests when the dissector processes malformed or specially crafted GVCP packets that cause the offset calculation mechanism to become trapped in a loop, consuming excessive CPU resources and rendering the network analysis tool unresponsive.
The technical root cause of this vulnerability lies in the packet-gvcp.c dissector implementation where offset handling logic fails to guarantee progressive advancement during packet parsing operations. Specifically, the dissector does not properly validate or increment offset values in all conditional branches, allowing for scenarios where the offset remains static or decreases, causing the parsing loop to continue indefinitely. This type of vulnerability falls under CWE-835, which specifically addresses infinite loops or other looping constructs that do not properly terminate. The issue demonstrates poor defensive programming practices where boundary conditions are not adequately checked, and loop termination criteria are not robust enough to handle all possible input scenarios.
From an operational impact perspective, this vulnerability presents significant risks to network security operations centers and forensic analysts who depend on Wireshark for real-time traffic monitoring and incident response activities. An attacker could exploit this vulnerability by crafting malicious GVCP packets and transmitting them to a victim system running the affected Wireshark version, causing the application to consume 100% CPU resources and become unresponsive. This denial of service condition would prevent legitimate network analysis activities and could be used to disrupt security monitoring operations in industrial control systems, surveillance networks, or enterprise environments where GVCP traffic is common. The vulnerability also aligns with ATT&CK technique T1499.004, which covers network disruption through resource exhaustion attacks, making it a significant concern for operational technology security.
The mitigation for CVE-2020-15466 involves updating to Wireshark version 3.2.5 or later, where the fix ensures that offset values consistently increase during packet processing regardless of input conditions. This patch implements proper boundary checking and loop termination conditions within the GVCP dissector to prevent the infinite loop scenario. Network administrators should also consider implementing network segmentation and access controls to limit exposure to potentially malicious GVCP traffic, while security teams should monitor for unusual CPU consumption patterns that might indicate exploitation attempts. Additionally, organizations using industrial protocols should conduct regular vulnerability assessments of their network monitoring tools to ensure they remain protected against similar issues in other dissector components. The fix demonstrates the importance of defensive programming practices and proper input validation in network protocol analysis tools, as outlined in security best practices for network security applications.