CVE-2017-3806 in Firepower 4100
Summary
by MITRE
A vulnerability in CLI command processing in the Cisco Firepower 4100 Series Next-Generation Firewall and Cisco Firepower 9300 Security Appliance could allow an authenticated, local attacker to inject arbitrary shell commands that are executed by the device. More Information: CSCvb61343. Known Affected Releases: 2.0(1.68). Known Fixed Releases: 2.0(1.118) 2.1(1.47) 92.1(1.1646) 92.1(1.1763) 92.2(1.101).
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Analysis
by VulDB Data Team • 02/03/2017
The vulnerability identified as CVE-2017-3806 represents a critical command injection flaw within the command line interface processing of Cisco Firepower 4100 Series Next-Generation Firewalls and Cisco Firepower 9300 Security Appliances. This security weakness stems from inadequate input validation mechanisms within the device's CLI command handling system, allowing authenticated local users to exploit a fundamental design flaw that could lead to complete system compromise. The vulnerability specifically affects devices running software versions 2.0(1.68) and earlier, with remediation available through several patched releases including 2.0(1.118), 2.1(1.47), 92.1(1.1646), 92.1(1.1763), and 92.2(1.101). The flaw manifests when legitimate CLI commands are processed without proper sanitization of user-supplied input, creating an environment where maliciously crafted input can be interpreted and executed as shell commands by the underlying operating system.
This vulnerability directly maps to CWE-77 in the Common Weakness Enumeration catalog, which specifically addresses "Improper Neutralization of Special Elements used in a Command ('Command Injection')". The technical implementation flaw occurs in the command processing pipeline where user input is not adequately filtered or escaped before being passed to shell execution functions. The attack vector requires local authentication, meaning an attacker must first establish valid credentials on the device before exploiting this vulnerability. However, the impact remains severe because once authenticated, the attacker can execute arbitrary commands with the privileges of the CLI user, potentially escalating to root-level access depending on the device configuration and user permissions.
The operational impact of CVE-2017-3806 extends far beyond simple command execution, as it provides attackers with a persistent foothold within the network security infrastructure. An attacker who successfully exploits this vulnerability can manipulate firewall rules, disable security features, redirect traffic, or establish backdoor access points that persist across system reboots. The vulnerability creates a significant risk to network security posture since firewalls serve as critical boundary protection devices, and compromising their integrity can lead to complete network infiltration. The attack surface is particularly concerning given that these appliances are designed to protect enterprise networks, making them prime targets for sophisticated attackers seeking long-term access to sensitive environments.
Mitigation strategies for this vulnerability should include immediate deployment of the patched software versions mentioned in the advisory, along with comprehensive network segmentation and access control measures. Organizations should implement principle of least privilege for CLI access, ensuring that only authorized personnel have local access to these devices. Network monitoring should be enhanced to detect anomalous CLI command patterns, and regular security audits should verify that no unauthorized access has occurred. The vulnerability also aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter, specifically shell commands, and T1068 for Exploitation for Privilege Escalation, as it allows for both command execution and potential privilege elevation. Device administrators should conduct thorough vulnerability assessments to ensure all affected appliances are properly updated and that proper access controls are implemented to prevent unauthorized local access to these critical security devices.