CVE-2011-4023 in NX-OS
Summary
by MITRE
Memory leak in libcmd in Cisco NX-OS 5.0 on Nexus switches allows remote authenticated users to cause a denial of service (memory consumption) via SNMP requests, aka Bug ID CSCtr65682.
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Analysis
by VulDB Data Team • 05/04/2019
The vulnerability identified as CVE-2011-4023 represents a critical memory leak flaw within the libcmd library of Cisco NX-OS version 5.0 running on Nexus switches. This issue manifests as a remote authenticated denial of service condition that specifically targets the Simple Network Management Protocol implementation within the affected network infrastructure devices. The vulnerability was catalogued under Cisco Bug ID CSCtr65682, highlighting its significance within the vendor's internal tracking systems. The flaw occurs when the system processes SNMP requests from authenticated users, causing progressive memory consumption that eventually leads to system instability and service disruption.
The technical implementation of this vulnerability stems from improper memory management within the libcmd library component that handles command processing for the NX-OS operating system. When legitimate SNMP requests are processed through the affected switches, the system fails to properly release allocated memory blocks back to the system heap. This memory leak accumulates over time as successive SNMP operations are performed, gradually consuming available system resources. The flaw specifically affects authenticated users who can establish valid SNMP sessions with the switch, making it exploitable by individuals with legitimate network access credentials. The memory consumption pattern is typically gradual but persistent, allowing attackers to monitor and predict the timeline for system degradation.
From an operational impact perspective, this vulnerability presents a significant risk to network availability and reliability. Network administrators may observe progressive performance degradation of Nexus switches as memory resources become increasingly constrained, potentially leading to complete system crashes or restarts. The authenticated nature of the attack means that malicious actors would need valid credentials to exploit the vulnerability, but this requirement does not mitigate the risk since legitimate administrative accounts may be compromised or accessible to unauthorized users. The impact extends beyond simple service disruption to potentially affecting critical network infrastructure operations, particularly in environments where Nexus switches serve as core routing or switching devices.
The vulnerability aligns with CWE-401, which specifically addresses memory leaks in software implementations, and demonstrates characteristics consistent with the attack pattern described in the MITRE ATT&CK framework under the T1499 category for network denial of service attacks. Organizations should implement immediate mitigations including applying Cisco's recommended security patches and updates to resolve the memory leak issue. Network segmentation and access controls should be strengthened to limit SNMP access to only authorized administrative users, while monitoring systems should be deployed to track memory consumption patterns and detect potential exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify similar memory management flaws in other network infrastructure components, ensuring comprehensive protection against similar threats that could compromise network availability and operational integrity.