CVE-2021-26104 in FortiManager
Summary
by MITRE • 04/06/2022
Multiple OS command injection (CWE-78) vulnerabilities in the command line interface of FortiManager 6.2.7 and below, 6.4.5 and below and all versions of 6.2.x, 6.0.x and 5.6.x, FortiAnalyzer 6.2.7 and below, 6.4.5 and below and all versions of 6.2.x, 6.0.x and 5.6.x, and FortiPortal 5.2.5 and below, 5.3.5 and below and 6.0.4 and below may allow a local authenticated and unprivileged user to execute arbitrary shell commands as root via specifically crafted CLI command parameters.
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Analysis
by VulDB Data Team • 04/08/2022
The vulnerability identified as CVE-2021-26104 represents a critical operating system command injection flaw affecting multiple Fortinet security appliances including FortiManager, FortiAnalyzer, and FortiPortal devices. This vulnerability resides within the command line interface implementation and manifests as a CWE-78 operating system command injection weakness that allows attackers to execute arbitrary shell commands with root privileges. The flaw impacts a broad range of versions across multiple product lines, specifically targeting FortiManager versions 6.2.7 and below, 6.4.5 and below, and all versions of 6.2.x, 6.0.x, and 5.6.x series, along with corresponding FortiAnalyzer and FortiPortal versions. The vulnerability is particularly concerning because it requires only local authentication and does not demand privileged access, making it exploitable by any authenticated user within the system.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the command line interface processing logic. When users submit specifically crafted CLI command parameters, the system fails to properly escape or filter special characters that could be interpreted by the underlying operating system shell. This allows malicious input to be executed as shell commands rather than being treated as simple parameter values. The flaw is particularly dangerous because it operates at the root level of the operating system, meaning that successful exploitation results in complete system compromise with administrative privileges. Attackers can leverage this vulnerability to gain unauthorized access to sensitive data, modify system configurations, install malware, or establish persistent backdoors within the network infrastructure.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally compromises the security posture of Fortinet appliances deployed in enterprise environments. Organizations using affected versions face significant risk of unauthorized system access, data breaches, and potential lateral movement within their networks. The vulnerability's persistence across multiple major versions and product lines indicates a systemic issue in the software development lifecycle, potentially affecting thousands of deployments worldwide. Security teams must consider the implications for network monitoring, incident response procedures, and overall security architecture, as this vulnerability undermines the integrity of security appliances that are typically considered trusted components within enterprise security infrastructures.
Mitigation strategies for CVE-2021-26104 should prioritize immediate software updates to patched versions as provided by Fortinet, following the vendor's security advisory releases. Organizations should implement network segmentation to limit access to these appliances and enforce strict access controls, ensuring that only authorized personnel can access the command line interfaces. Additional defensive measures include regular security audits of system configurations, monitoring for unusual command execution patterns, and implementing intrusion detection systems that can identify potential exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and command and control communications, requiring security teams to monitor for indicators of compromise related to unauthorized root-level command execution. The vulnerability also highlights the importance of input validation practices and secure coding standards, particularly in CLI implementations, as recommended by industry security frameworks and standards.