CVE-2016-6384 in IOS
Summary
by MITRE
Cisco IOS 12.2 through 12.4 and 15.0 through 15.6 and IOS XE 3.1 through 3.17 and 16.2 allow remote attackers to cause a denial of service (device reload) via crafted fields in an H.323 message, aka Bug ID CSCux04257.
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Analysis
by VulDB Data Team • 09/24/2024
Cisco IOS devices running versions 12.2 through 12.4 and 15.0 through 15.6, as well as IOS XE versions 3.1 through 3.17 and 16.2, contain a critical vulnerability in their H.323 protocol handling implementation that enables remote attackers to trigger unauthorized device reboots. This vulnerability manifests when the system processes malformed or specially crafted H.323 messages containing aberrant field values that are not properly validated or sanitized during message parsing. The flaw exists in the H.323 gateway functionality where the device fails to adequately validate incoming message fields, leading to memory corruption or unexpected behavior that ultimately results in system instability and device reload operations.
The technical nature of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which addresses out-of-bounds read errors. When an attacker sends specifically crafted H.323 messages with malformed fields, the IOS system attempts to parse these inputs without sufficient validation mechanisms, causing the device to crash and subsequently reload its operating system. This behavior represents a denial of service condition that can be exploited remotely without requiring authentication, making it particularly dangerous in network environments where H.323 traffic is processed or where devices are accessible from untrusted networks. The vulnerability specifically impacts the H.323 signaling protocol implementation within the IOS operating system, which is commonly used in voice and video communication systems for call setup and control.
From an operational impact perspective, this vulnerability poses significant risk to organizations relying on Cisco voice infrastructure, as it can be leveraged to disrupt critical communication services without requiring any privileged access. The remote exploitation capability means that attackers can target vulnerable devices from outside the network perimeter, potentially causing widespread disruption to voice services, video conferencing, and other H.323-dependent applications. The automatic device reload operation effectively creates a service interruption that can last several minutes, depending on the device configuration and recovery time. Network administrators may experience cascading effects as voice services become unavailable, impacting business operations and potentially affecting mission-critical communications in enterprise and service provider environments.
Organizations should implement immediate mitigations including disabling H.323 functionality on affected devices when not required, applying the relevant Cisco security patches that address the buffer overflow conditions in the H.323 message processing code, and implementing network segmentation to limit exposure of vulnerable devices to untrusted networks. The ATT&CK framework categorizes this vulnerability under T1499.004 for network denial of service and T1595.001 for network scanning, as attackers may use this vulnerability to identify and exploit vulnerable systems within their network infrastructure. Additional defensive measures should include monitoring for unusual H.323 traffic patterns and implementing proper access controls to prevent unauthorized access to devices that process H.323 signaling messages. The vulnerability demonstrates the importance of input validation and proper error handling in network protocol implementations, as outlined in the OWASP Top 10 security principles, particularly focusing on proper data validation and robust error handling mechanisms.