CVE-2018-0455 in Firepower System Software
Summary
by MITRE
A vulnerability in the Server Message Block Version 2 (SMBv2) and Version 3 (SMBv3) protocol implementation for the Cisco Firepower System Software could allow an unauthenticated, remote attacker to cause the device to run low on system memory, possibly preventing the device from forwarding traffic. It is also possible that a manual reload of the device may be required to clear the condition. The vulnerability is due to incorrect SMB header validation. An attacker could exploit this vulnerability by sending a custom SMB file transfer through the targeted device. A successful exploit could cause the device to consume an excessive amount of system memory and prevent the SNORT process from forwarding network traffic. This vulnerability can be exploited using either IPv4 or IPv6 in combination with SMBv2 or SMBv3 network traffic.
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Analysis
by VulDB Data Team • 03/30/2020
The vulnerability identified as CVE-2018-0455 represents a critical memory exhaustion flaw within the Server Message Block protocol implementation of Cisco Firepower System Software. This weakness specifically affects SMBv2 and SMBv3 protocol versions, creating a pathway for remote attackers to systematically deplete system resources without requiring authentication credentials. The vulnerability stems from inadequate validation of SMB headers during packet processing, allowing maliciously crafted network traffic to trigger abnormal memory consumption patterns within the affected firewalls. The flaw manifests when the system processes specially crafted SMB file transfer requests, causing the device to allocate excessive memory resources that eventually lead to service disruption. According to the Common Weakness Enumeration framework, this vulnerability maps to CWE-129, which describes improper validation of input boundaries, and more specifically aligns with CWE-400, concerning unchecked resource consumption. The attack vector operates through either IPv4 or IPv6 networks, making it particularly dangerous as it can be exploited across different network protocols. The impact extends beyond simple service degradation, as the vulnerability can effectively prevent the SNORT process from forwarding network traffic, thereby compromising the firewall's core functionality and network security posture.
The operational consequences of CVE-2018-0455 pose significant risks to enterprise network infrastructure, particularly in environments where Cisco Firepower devices serve as primary security gateways. When exploited successfully, the vulnerability creates a resource exhaustion condition that can lead to complete service disruption, forcing network administrators to perform manual device reloads to restore normal operations. This disruption directly impacts the availability and reliability of network security services, potentially creating windows of vulnerability where malicious traffic can bypass security controls. The attack scenario involves sending crafted SMB packets that exploit the header validation flaw, causing the system to continuously allocate memory without proper bounds checking. This behavior aligns with the MITRE ATT&CK framework's T1499 technique for network denial of service, specifically targeting the availability of network services through resource exhaustion attacks. The vulnerability's exploitation capability across both SMBv2 and SMBv3 protocols, combined with support for both IPv4 and IPv6 networks, increases the attack surface and makes it particularly challenging to defend against. Organizations running vulnerable Firepower systems face the risk of sustained denial of service conditions that can persist until manual intervention occurs, potentially leaving critical network segments unprotected during the recovery period.
Mitigation strategies for CVE-2018-0455 require immediate implementation of both network-level and device-level controls to prevent exploitation. Cisco has released patches and software updates specifically addressing this vulnerability, which should be deployed as a priority across all affected Firepower systems. Network administrators should implement access control lists and firewall rules that block SMB traffic at the network perimeter, particularly targeting ports 445 and 139 used by SMB protocols. The implementation of rate limiting and connection tracking mechanisms can help detect and prevent the excessive memory consumption patterns associated with this vulnerability. Organizations should also consider implementing network segmentation strategies to limit the potential impact of exploitation, ensuring that critical network services are isolated from potentially compromised segments. Monitoring and logging capabilities should be enhanced to detect anomalous memory usage patterns and unusual SMB traffic patterns that may indicate exploitation attempts. According to industry best practices and security frameworks, this vulnerability requires immediate remediation as it represents a critical threat to network availability and security. The patching process should be carefully planned to minimize service disruption while ensuring complete protection against the memory exhaustion attack vector. Additionally, implementing network intrusion detection systems with signatures specifically designed to identify CVE-2018-0455 exploitation attempts can provide early warning capabilities. Regular vulnerability assessments and penetration testing should be conducted to verify the effectiveness of implemented controls and identify any potential bypass mechanisms that attackers might employ against the mitigations.