CVE-2018-0233 in Firepower System Software
Summary
by MITRE
A vulnerability in the Secure Sockets Layer (SSL) packet reassembly functionality of the detection engine in Cisco Firepower System Software could allow an unauthenticated, remote attacker to cause the detection engine to consume excessive system memory on an affected device, which could cause a denial of service (DoS) condition. The vulnerability is due to the affected software improperly handling changes to SSL connection states. An attacker could exploit this vulnerability by sending crafted SSL connections through an affected device. A successful exploit could allow the attacker to cause the detection engine to consume excessive system memory on the affected device, which could cause a DoS condition. The device may need to be reloaded manually to recover from this condition. This vulnerability affects Cisco Firepower System Software Releases 6.0.0 and later, running on any of the following Cisco products: Adaptive Security Appliance (ASA) 5500-X Series Firewalls with FirePOWER Services, Adaptive Security Appliance (ASA) 5500-X Series Next-Generation Firewalls, Advanced Malware Protection (AMP) for Networks, 7000 Series Appliances, Advanced Malware Protection (AMP) for Networks, 8000 Series Appliances, Firepower 4100 Series Appliances, FirePOWER 7000 Series Appliances, FirePOWER 8000 Series Appliances, Firepower 9300 Series Security Appliances, Firepower Threat Defense for Integrated Services Routers (ISRs), Firepower Threat Defense Virtual for VMware, Industrial Security Appliance 3000, Sourcefire 3D System Appliances. Cisco Bug IDs: CSCve23031.
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Analysis
by VulDB Data Team • 11/26/2024
The vulnerability described in CVE-2018-0233 represents a critical denial of service weakness within Cisco Firepower System Software that specifically targets the Secure Sockets Layer packet reassembly functionality of the detection engine. This flaw exists in the way the software processes SSL connection state changes, creating a condition where malformed SSL traffic can trigger excessive memory consumption within the detection engine. The vulnerability affects multiple Cisco security appliances including ASA 5500-X Series firewalls, Firepower 4100, 7000, 8000, and 9300 series appliances, as well as various AMP for Networks appliances and industrial security appliances. The issue stems from improper handling of SSL connection state transitions that occur during the packet reassembly process, leading to memory allocation patterns that can rapidly consume available system resources.
The technical exploitation of this vulnerability occurs when an unauthenticated remote attacker sends specifically crafted SSL connections through an affected Cisco device. The attack leverages the detection engine's failure to properly manage memory allocation when processing SSL state changes, causing the system to continuously allocate memory without proper cleanup or bounds checking. This memory consumption pattern can escalate rapidly, potentially leading to complete system exhaustion where the device becomes unresponsive and unable to process legitimate network traffic. The vulnerability is particularly dangerous because it requires no authentication credentials to exploit, making it accessible to any remote attacker with network access to the affected device. The memory consumption occurs within the detection engine's SSL packet reassembly module, which is responsible for analyzing and processing encrypted traffic passing through the firewall.
The operational impact of this vulnerability can be severe for organizations relying on Cisco Firepower devices for network security. A successful exploitation can result in complete denial of service conditions where the affected device becomes unusable and must be manually reloaded to restore functionality. This disruption can affect network availability and potentially leave critical infrastructure exposed to other threats during the recovery period. The vulnerability affects all Cisco Firepower System Software releases 6.0.0 and later, meaning that a significant number of deployed security appliances could be impacted. Organizations using the affected devices may experience extended downtime as they must manually reboot or reload the affected systems to recover from the memory exhaustion condition. The need for manual intervention increases the operational burden on security teams and can create gaps in network protection during recovery operations.
Mitigation strategies for CVE-2018-0233 should focus on both immediate protective measures and long-term system hardening approaches. Cisco recommends applying the latest software patches and updates to address the vulnerability, which would include upgrading to versions that properly handle SSL connection state changes and implement appropriate memory management controls. Network administrators should also consider implementing access control lists to limit SSL traffic to only necessary sources, reducing the attack surface for potential exploitation. Additionally, monitoring systems should be configured to detect unusual memory consumption patterns in Firepower devices, providing early warning of potential exploitation attempts. The vulnerability aligns with CWE-129, which addresses improper handling of buffer length, and falls under ATT&CK technique T1499.004 for network denial of service attacks. Organizations should also implement network segmentation to limit the potential impact of successful exploitation and maintain robust backup and recovery procedures for their security infrastructure.