CVE-2015-0619 in ASA
Summary
by MITRE
Memory leak in the embedded web server in the WebVPN subsystem in Cisco Adaptive Security Appliance (ASA) Software allows remote attackers to cause a denial of service (memory consumption and SSL outage) via multiple crafted HTTP requests, aka Bug ID CSCue05458.
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Analysis
by VulDB Data Team • 12/02/2024
The vulnerability identified as CVE-2015-0619 represents a critical memory leak flaw within the embedded web server component of Cisco Adaptive Security Appliance (ASA) software, specifically affecting the WebVPN subsystem. This issue manifests as a remote denial of service condition that can be exploited by attackers positioned outside the network perimeter. The vulnerability stems from insufficient memory management within the web server implementation, allowing malicious actors to consume system resources through carefully crafted HTTP requests that trigger memory allocation without proper deallocation. The flaw affects Cisco ASA software versions prior to 9.1(2) and represents a significant weakness in the appliance's ability to maintain stable operation under adversarial conditions.
The technical implementation of this vulnerability involves the embedded web server's failure to properly handle memory allocation for HTTP request processing within the WebVPN context. When multiple crafted HTTP requests are submitted to the affected system, the web server allocates memory buffers to process these requests but fails to release the allocated memory back to the system upon completion of request handling. This progressive memory consumption eventually leads to system resource exhaustion, causing the appliance to become unresponsive and resulting in both memory consumption issues and SSL service outages. The flaw operates at the application layer and leverages the HTTP protocol to deliver the malicious payload, making it particularly dangerous as it can be exploited without requiring authentication or privileged access.
The operational impact of CVE-2015-0619 extends beyond simple service disruption to encompass potential business continuity implications for organizations relying on Cisco ASA appliances for network security. The memory leak can cause cascading failures where the appliance becomes increasingly unstable over time, potentially leading to complete service outages that affect VPN connectivity for legitimate users. Network administrators may experience difficulty in diagnosing the root cause due to the gradual nature of memory consumption, making the vulnerability particularly insidious. The SSL outage component specifically impacts secure remote access capabilities, which can compromise both availability and security posture for organizations dependent on encrypted VPN connections. This vulnerability aligns with CWE-401, which describes improper handling of memory allocation and deallocation, and can be mapped to ATT&CK technique T1499.004 for network denial of service attacks.
Mitigation strategies for CVE-2015-0619 primarily focus on applying the vendor-provided security patches and software updates that address the memory management flaws within the embedded web server. Cisco released ASA software versions 9.1(2) and later that contain fixes for this vulnerability, making immediate patch deployment the most effective remediation approach. Organizations should also implement network monitoring solutions to detect unusual memory consumption patterns that may indicate exploitation attempts, as well as establish temporary network segmentation measures to limit the potential impact of successful attacks. Network administrators should consider implementing rate limiting or request filtering mechanisms at the perimeter to reduce the effectiveness of memory exhaustion attacks, though these measures represent temporary workarounds rather than permanent solutions. The vulnerability demonstrates the importance of maintaining up-to-date security software and implementing robust patch management processes to prevent exploitation of known memory management flaws that can lead to significant service disruption.