CVE-2016-6385 in IOS
Summary
by MITRE
Memory leak in the Smart Install client implementation in Cisco IOS 12.2 and 15.0 through 15.2 and IOS XE 3.2 through 3.8 allows remote attackers to cause a denial of service (memory consumption) via crafted image-list parameters, aka Bug ID CSCuy82367.
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Analysis
by VulDB Data Team • 04/29/2019
The vulnerability identified as CVE-2016-6385 represents a critical memory leak flaw within Cisco IOS and IOS XE implementations that affects versions 12.2 and 15.0 through 15.2, along with IOS XE 3.2 through 3.8. This issue resides in the Smart Install client functionality, which is designed to facilitate remote software deployment and management of network devices. The flaw manifests when the system processes crafted image-list parameters, leading to uncontrolled memory consumption that can ultimately result in system instability and denial of service conditions. The vulnerability operates at the network infrastructure level, targeting the core operating system functionality that manages device software updates and configurations.
The technical implementation of this memory leak stems from insufficient input validation within the Smart Install client processing logic. When the system receives malformed image-list parameters containing specially crafted data structures, the memory allocation routines fail to properly release allocated memory blocks after processing. This improper memory management creates a progressive accumulation of unreleased memory segments that gradually consumes available system resources. The vulnerability follows a classic pattern of memory leak exploitation as defined by CWE-401, where the system fails to properly manage dynamic memory allocation and deallocation cycles. The flaw is particularly dangerous because it can be triggered remotely without requiring authentication, making it accessible to any attacker who can reach the affected device's management interfaces.
The operational impact of this vulnerability extends beyond simple resource exhaustion, creating cascading effects that can compromise entire network segments. As memory consumption increases, the device may experience performance degradation, application crashes, or complete system restarts, effectively denying network services to legitimate users. Network administrators face the challenge of maintaining device availability while managing the risk of unpatched systems, particularly in large enterprise environments where multiple devices may be vulnerable simultaneously. The vulnerability directly maps to ATT&CK technique T1499.001, which describes resource exhaustion attacks targeting network infrastructure devices, and represents a significant threat to network availability and business continuity.
Mitigation strategies for CVE-2016-6385 require immediate implementation of both temporary workarounds and permanent patching procedures. Organizations should prioritize applying Cisco's official security patches that address the memory leak in Smart Install client processing, while also implementing network segmentation to limit exposure to untrusted networks. Temporary measures include disabling Smart Install functionality on affected devices, implementing strict access controls to management interfaces, and monitoring system memory usage for unusual consumption patterns. Network administrators must also establish proactive monitoring protocols to detect early signs of memory exhaustion, as the vulnerability can be exploited without generating obvious network traffic anomalies. The remediation process should follow industry best practices for vulnerability management and include comprehensive testing of patches in controlled environments before widespread deployment to ensure operational stability.