CVE-2018-0240 in ASA
Summary
by MITRE
Multiple vulnerabilities in the Application Layer Protocol Inspection feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to trigger a reload of an affected device, resulting in a denial of service (DoS) condition. The vulnerabilities are due to logical errors during traffic inspection. An attacker could exploit these vulnerabilities by sending a high volume of malicious traffic across an affected device. An exploit could allow the attacker to cause a deadlock condition, resulting in a reload of an affected device. These vulnerabilities affect Cisco ASA Software and Cisco FTD Software configured for Application Layer Protocol Inspection running on the following Cisco products: 3000 Series Industrial Security Appliance (ISA), ASA 5500 Series Adaptive Security Appliances, ASA 5500-X Series Next-Generation Firewalls, ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers, Adaptive Security Virtual Appliance (ASAv), Firepower 2100 Series Security Appliance, Firepower 4100 Series Security Appliance, Firepower 9300 ASA Security Module, FTD Virtual (FTDv). Cisco Bug IDs: CSCve61540, CSCvh23085, CSCvh95456.
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Analysis
by VulDB Data Team • 03/03/2023
The vulnerability identified as CVE-2018-0240 represents a critical denial of service flaw within Cisco's Adaptive Security Appliance and Firepower Threat Defense software implementations. This issue specifically targets the Application Layer Protocol Inspection feature, which serves as a fundamental component for deep packet inspection and protocol analysis in network security devices. The logical errors embedded within the traffic inspection mechanisms create exploitable conditions that can be leveraged by remote attackers without requiring authentication credentials. These vulnerabilities exist across multiple Cisco security appliance platforms including the 3000 Series Industrial Security Appliances, various ASA 5500 series models, and Firepower series devices, making them particularly concerning given the widespread deployment of these security solutions in enterprise and industrial environments.
The technical exploitation of CVE-2018-0240 occurs through the manipulation of traffic patterns that trigger specific logical flaws during the application layer protocol inspection process. When an attacker sends a high volume of maliciously crafted traffic through an affected device, the system's inspection logic encounters conditions that lead to deadlock scenarios within the processing threads. This deadlock condition forces the affected device to undergo an automatic reload process as a recovery mechanism, effectively disrupting network connectivity and service availability. The vulnerability's impact is amplified by the fact that it requires no authentication credentials, making it particularly dangerous as any remote attacker with network access can potentially exploit these conditions. The logical errors in the traffic inspection algorithms create a cascade of failures that ultimately result in system instability and forced device restarts.
The operational impact of CVE-2018-0240 extends beyond simple service disruption to encompass potential business continuity issues and operational security concerns. Organizations relying on Cisco ASA and FTD appliances for network protection face significant risks when these devices become unavailable due to the denial of service conditions. The automatic reload process creates temporary network outages that can affect critical infrastructure operations, particularly in industrial control systems where the 3000 Series ISA appliances are commonly deployed. Network administrators must contend with the possibility of repeated service interruptions as attackers can potentially exploit the vulnerability multiple times, leading to sustained disruption of security services. The vulnerability affects both hardware and virtualized implementations including the ASAv and FTDv platforms, indicating that the flaw is architectural rather than specific to particular deployment methods.
Mitigation strategies for CVE-2018-0240 should focus on both immediate protective measures and long-term architectural considerations. Cisco has released patches and software updates addressing the logical errors within the Application Layer Protocol Inspection feature, which should be deployed immediately across all affected systems. Network administrators should implement traffic filtering measures to reduce the volume of potentially malicious traffic reaching the affected devices, particularly focusing on protocol inspection bypass techniques. The implementation of monitoring solutions that can detect abnormal traffic patterns and device reload events provides early warning capabilities for potential exploitation attempts. Organizations should also consider temporarily disabling the Application Layer Protocol Inspection feature when the risk of exploitation is high, though this reduces the security appliance's ability to perform deep packet analysis. From a compliance standpoint, this vulnerability aligns with CWE-472 Unprotected Primary Resource and addresses ATT&CK techniques related to denial of service and system compromise. The vulnerability demonstrates the importance of robust input validation and error handling in security appliances, as the logical flaws in traffic inspection create conditions that can be exploited to cause system instability and service disruption.