CVE-2018-0272 in Firepower System Software
Summary
by MITRE
A vulnerability in the Secure Sockets Layer (SSL) Engine of Cisco Firepower System Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to improper error handling while processing SSL traffic. An attacker could exploit this vulnerability by sending a large volume of crafted SSL traffic to the vulnerable device. A successful exploit could allow the attacker to degrade the device performance by triggering a persistent high CPU utilization condition. Cisco Bug IDs: CSCvh89340.
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Analysis
by VulDB Data Team • 01/30/2020
The vulnerability identified as CVE-2018-0272 resides within the Secure Sockets Layer SSL Engine of Cisco Firepower System Software, representing a critical weakness that undermines the system's ability to maintain consistent service availability. This flaw specifically manifests in the improper error handling mechanisms that govern how SSL traffic is processed, creating a pathway for malicious actors to exploit the system's response to malformed or crafted SSL requests. The vulnerability affects Cisco Firepower devices running software versions that incorporate the affected SSL engine components, making it particularly concerning given the widespread deployment of these security appliances in enterprise environments where continuous network protection is essential.
The technical exploitation of this vulnerability occurs through the deliberate injection of crafted SSL traffic volumes that trigger specific error conditions within the SSL engine's processing pipeline. When the system encounters these malformed requests, the improper error handling causes the device to enter a state of persistent high CPU utilization, effectively consuming system resources and degrading overall performance. The attacker does not require authentication credentials to initiate this attack, making it particularly dangerous as it can be executed remotely without prior access to the network infrastructure. The vulnerability's design flaw lies in the lack of adequate input validation and error recovery mechanisms within the SSL processing module, which fails to properly terminate or isolate problematic traffic streams.
From an operational impact perspective, this vulnerability creates a significant risk of denial of service conditions that can severely disrupt network security operations and business continuity. The persistent high CPU utilization that results from exploitation can cause the affected Cisco Firepower device to become unresponsive or significantly slow down its packet processing capabilities, potentially allowing malicious traffic to bypass security controls or causing legitimate network traffic to experience delays. Network administrators may find their security infrastructure degraded during an attack, leaving their networks vulnerable to other threats while the system struggles to maintain basic functionality. The vulnerability's remote nature means that attackers can target these devices from anywhere on the internet, making it particularly dangerous for organizations that do not properly segment their security infrastructure.
Organizations should implement immediate mitigations including applying the latest security patches provided by Cisco to address the SSL engine error handling flaws. Network segmentation strategies should be employed to isolate vulnerable Firepower devices from critical network segments, while monitoring systems should be enhanced to detect unusual CPU utilization patterns that may indicate exploitation attempts. The vulnerability aligns with CWE-20, which describes improper input validation, and represents a classic example of how insufficient error handling can lead to resource exhaustion attacks. From an ATT&CK framework perspective, this vulnerability maps to techniques involving denial of service and resource exhaustion, specifically targeting the availability component of the CIA triad. Organizations should also consider implementing rate limiting controls on SSL traffic and establishing baseline performance metrics to quickly identify when systems begin exhibiting abnormal CPU utilization patterns that could indicate exploitation of this vulnerability.