CVE-2019-17650 in FortiClient
Summary
by MITRE
An Improper Neutralization of Special Elements used in a Command vulnerability in one of FortiClient for Mac OS root processes, may allow a local user of the system on which FortiClient is running to execute unauthorized code as root by bypassing a security check.
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Analysis
by VulDB Data Team • 11/22/2019
This vulnerability represents a critical command injection flaw in FortiClient for Mac OS that resides within a root process, creating a significant escalation path for local attackers. The issue stems from improper neutralization of special command elements, allowing malicious input to be interpreted as executable commands rather than data. When FortiClient executes commands through system calls, the application fails to properly sanitize user-supplied input or environmental variables that may be passed to shell execution functions. This weakness enables an attacker with local system access to craft malicious inputs that bypass existing security checks, ultimately gaining root privileges through the vulnerable root process. The vulnerability is particularly concerning because it operates within a privileged context, meaning successful exploitation directly results in full system compromise without requiring additional attack vectors or privilege escalation techniques.
The technical implementation of this vulnerability aligns with CWE-78, which specifically addresses Improper Neutralization of Special Elements used in OS Command Injection. This classification indicates that FortiClient fails to properly validate or escape command arguments before passing them to operating system commands, creating an environment where attacker-controlled data can be interpreted as shell commands. The root process context amplifies the risk significantly, as any successful exploitation directly translates to system-level compromise. Attackers can leverage this vulnerability by manipulating input fields or environment variables that FortiClient uses to execute system commands, bypassing the intended security mechanisms that should prevent unauthorized command execution. This type of vulnerability is particularly dangerous in enterprise environments where endpoint security solutions like FortiClient are deployed, as it provides a direct path to system compromise through legitimate security software.
The operational impact of CVE-2019-17650 extends beyond simple privilege escalation, creating potential for extensive system compromise and data exfiltration. Once an attacker gains root access through this vulnerability, they can manipulate system files, install persistent backdoors, disable security features, and access all system resources including encrypted data and network communications. The vulnerability's presence in a root process means that any security monitoring or detection mechanisms within FortiClient itself become ineffective, as the attacker operates at the highest privilege level. This creates a scenario where the security solution becomes a vector for attack rather than a protective measure. Additionally, the local user requirement for exploitation reduces the attack surface complexity but still poses significant risk in environments where local access is possible, such as shared workstations or compromised user accounts.
Mitigation strategies should focus on immediate patching of affected FortiClient versions and implementation of additional security controls to reduce the attack surface. Organizations should ensure that FortiClient is updated to versions that address the command injection vulnerability and implement proper input validation and sanitization measures. System administrators should consider restricting local user access where possible and monitor for unusual command execution patterns that might indicate exploitation attempts. The use of application whitelisting and mandatory access controls can provide additional defense in depth, preventing unauthorized code execution even if the vulnerability is exploited. Security monitoring should include detection of suspicious command execution patterns and unusual privilege escalation events, particularly in system logs and audit trails. Organizations should also consider implementing principle of least privilege for FortiClient processes and regularly review system configurations to ensure that security checks remain effective against such vulnerabilities. This remediation approach aligns with ATT&CK technique T1059.003 for Command and Scripting Interpreter, emphasizing the importance of proper input validation and privilege separation in preventing command injection attacks.