CVE-2021-1448 in Firepower Threat Defense
Summary
by MITRE • 04/30/2021
A vulnerability in the CLI of Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, local attacker to execute arbitrary commands with root privileges on the underlying operating system of an affected device that is running in multi-instance mode. This vulnerability is due to insufficient validation of user-supplied command arguments. An attacker could exploit this vulnerability by submitting crafted input to the affected command. A successful exploit could allow the attacker to execute commands on the underlying operating system with root privileges.
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Analysis
by VulDB Data Team • 05/03/2021
This vulnerability exists within the command line interface of Cisco Firepower Threat Defense software, representing a critical privilege escalation flaw that affects devices operating in multi-instance mode. The vulnerability stems from inadequate input validation mechanisms within the CLI processing functions, creating a pathway for authenticated local attackers to bypass normal security controls. The flaw specifically manifests when the system fails to properly sanitize command arguments passed through the interface, allowing malicious input to be interpreted as executable commands rather than simple parameters. This represents a classic command injection vulnerability that leverages the trust placed in local administrative interfaces.
The technical exploitation of CVE-2021-1448 requires an attacker to possess valid authentication credentials for the device, typically administrative access, but does not require network connectivity or external attack vectors. The vulnerability operates at the operating system level, where the insufficient validation allows crafted input to traverse the CLI boundary and execute within the privileged context of the underlying operating system. This creates a direct path for arbitrary code execution with root privileges, effectively providing complete system compromise. The multi-instance mode aspect of the vulnerability is particularly significant as it indicates the flaw affects virtualized environments where multiple instances share the same underlying operating system resources, potentially enabling lateral movement between instances. This vulnerability aligns with CWE-77 and CWE-78 categories from the Common Weakness Enumeration, specifically addressing command injection weaknesses in input validation.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise and potential data exfiltration capabilities. Once exploited, an attacker gains root access to the underlying operating system, enabling them to modify system files, install backdoors, disable security features, or extract sensitive information from the device. The multi-instance nature of the vulnerability also means that exploitation could potentially affect multiple virtual environments running on the same physical hardware, creating broader impact than a single instance compromise. Organizations using Cisco FTD software in multi-instance deployments face heightened risk as this vulnerability could be leveraged to gain unauthorized access to critical network security infrastructure, potentially disrupting network operations and providing attackers with persistent access to network traffic monitoring capabilities.
Mitigation strategies for CVE-2021-1448 should focus on immediate patch deployment from Cisco, as the vendor has released software updates addressing the input validation deficiencies. Network administrators should implement strict access controls and monitoring of CLI activities to detect potential exploitation attempts, particularly focusing on unusual command sequences or unexpected privilege escalation patterns. The principle of least privilege should be enforced by limiting administrative access to only necessary personnel and implementing multi-factor authentication for CLI access. Additionally, organizations should consider network segmentation and monitoring solutions to detect command execution activities that could indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and command and control activities, requiring defensive measures that address both the initial compromise vector and potential post-exploitation actions. Regular security assessments of network security devices should include verification of proper input validation mechanisms and monitoring of system logs for suspicious CLI activity patterns.