CVE-2018-0302 in FXOS
Summary
by MITRE
A vulnerability in the CLI parser of Cisco FXOS Software and Cisco UCS Fabric Interconnect Software could allow an authenticated, local attacker to cause a buffer overflow on an affected device. The vulnerability is due to incorrect input validation in the CLI parser subsystem. An attacker could exploit this vulnerability by exceeding the expected length of user input. A successful exploit could allow the attacker to execute arbitrary code with root privileges on the affected system. This vulnerability affects Firepower 4100 Series Next-Generation Firewall, Firepower 9300 Security Appliance, UCS 6100 Series Fabric Interconnects, UCS 6200 Series Fabric Interconnects, UCS 6300 Series Fabric Interconnects. Cisco Bug IDs: CSCvb61099, CSCvb86743.
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Analysis
by VulDB Data Team • 02/21/2020
The vulnerability identified as CVE-2018-0302 represents a critical buffer overflow flaw within the command line interface parser of Cisco FXOS Software and Cisco UCS Fabric Interconnect Software. This security weakness exists in the core input validation mechanisms of the CLI subsystem, creating a pathway for authenticated local attackers to manipulate system behavior through malformed input sequences. The vulnerability stems from inadequate bounds checking when processing user-provided command line arguments, allowing attackers to exceed predetermined buffer limits and overwrite adjacent memory regions. The affected platforms include Firepower 4100 Series Next-Generation Firewalls, Firepower 9300 Security Appliances, and multiple UCS Fabric Interconnect series spanning 6100, 6200, and 6300 generations, indicating a widespread impact across Cisco's security and data center infrastructure portfolio.
The technical exploitation of this vulnerability requires an attacker to possess valid authentication credentials for the affected device, as the flaw resides within the local CLI parser rather than external network interfaces. Attackers can trigger the buffer overflow by providing specially crafted command line inputs that exceed the expected character limits, causing memory corruption that can be leveraged to execute arbitrary code with elevated privileges. This privilege escalation capability means that successful exploitation would grant attackers root-level access to the affected system, potentially enabling complete compromise of the device's operational functions. The vulnerability's classification aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations, and also maps to ATT&CK technique T1059.001 for command and scripting interpreter usage.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally compromises the integrity and availability of critical network security infrastructure. Compromised firewalls and fabric interconnects could result in complete network segmentation failures, unauthorized access to protected network segments, and potential data exfiltration from sensitive environments. Organizations utilizing affected Cisco products face significant risk of persistent threats gaining root access to their security infrastructure, potentially enabling attackers to modify firewall rules, disable security features, or establish backdoor access points. The vulnerability's presence across multiple product lines suggests that organizations with heterogeneous Cisco environments may face cascading security implications, where compromise of one device type could potentially impact the entire network security architecture.
Mitigation strategies for CVE-2018-0302 should prioritize immediate deployment of Cisco's official security patches and firmware updates, which address the underlying input validation flaws in the CLI parser subsystem. Organizations should implement strict access controls and least privilege principles for CLI access, limiting authentication credentials to only necessary personnel and implementing multi-factor authentication where possible. Network segmentation and monitoring should be enhanced to detect anomalous CLI usage patterns that might indicate exploitation attempts, while regular security assessments should verify that all affected devices have been properly updated. The vulnerability's nature as a local privilege escalation issue also necessitates comprehensive audit logging of all CLI sessions and input activities, providing forensic capabilities to detect and respond to potential exploitation attempts. Additionally, organizations should consider implementing network access controls that restrict direct CLI access to critical infrastructure, relying instead on managed configuration interfaces that provide additional input validation layers.