CVE-2015-4238 in ASA
Summary
by MITRE
The SNMP implementation in Cisco Adaptive Security Appliance (ASA) Software 8.4(7) and 8.6(1.2) allows remote authenticated users to cause a denial of service (device reload) by sending many SNMP requests during a time of high network traffic, aka Bug ID CSCul02601.
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Analysis
by VulDB Data Team • 11/24/2024
The vulnerability described in CVE-2015-4238 represents a significant denial of service weakness within Cisco Adaptive Security Appliance software versions 8.4(7) and 8.6(1.2). This flaw specifically affects the SNMP implementation component of the ASA platform, which serves as a critical monitoring and management interface for network security devices. The vulnerability manifests when authenticated remote attackers exploit the system's handling of SNMP requests during periods of elevated network activity, leading to complete device restarts that disrupt network security operations.
The technical mechanism behind this vulnerability involves a buffer overflow or resource exhaustion condition within the SNMP processing code of the ASA software. When multiple SNMP requests are simultaneously processed during high network traffic periods, the system's memory management and request handling capabilities become overwhelmed. This condition falls under CWE-129, which addresses improper validation of the length of input data, and specifically relates to CWE-131, which covers improper handling of memory allocation failures. The flaw exploits the lack of proper rate limiting and resource management in the SNMP service implementation, allowing attackers to consume system resources faster than they can be replenished.
The operational impact of this vulnerability extends beyond simple service disruption to compromise the overall network security posture. When an ASA device reloads due to this vulnerability, it creates a window of exposure where network traffic flows through unmonitored paths, potentially allowing malicious actors to bypass security controls. This represents a direct violation of the principle of least privilege and availability, as the device fails to maintain its security function during attack conditions. The vulnerability also maps to ATT&CK technique T1499.004, which covers network denial of service attacks, and demonstrates how legitimate management protocols can be weaponized to compromise system availability. During high network traffic periods, the vulnerability becomes particularly dangerous as the system's already strained resources are further degraded by the malicious SNMP requests.
Mitigation strategies for this vulnerability require immediate implementation of several protective measures. Organizations should prioritize applying the vendor-provided security patches that address the SNMP processing logic and memory management issues in the affected ASA software versions. Network segmentation and access control lists should be implemented to restrict SNMP access to only trusted management systems, reducing the attack surface available to potential attackers. Additionally, implementing SNMP request rate limiting and monitoring protocols can help detect abnormal traffic patterns that may indicate exploitation attempts. The Cisco Security Advisory provides specific guidance for configuring these protections and recommends enabling logging for SNMP activities to facilitate threat detection. Network administrators should also consider implementing redundant security appliances and establishing automated failover mechanisms to maintain network security continuity during potential exploitation events.