CVE-2021-20037 in Global VPN Client
Summary
by MITRE • 09/21/2021
SonicWall Global VPN Client 4.10.5 installer (32-bit and 64-bit) incorrect default file permission vulnerability leads to privilege escalation which potentially allows command execution in the host operating system. This vulnerability impacts GVC 4.10.5 installer and earlier.
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Analysis
by VulDB Data Team • 10/01/2021
The SonicWall Global VPN Client vulnerability CVE-2021-20037 represents a critical privilege escalation flaw that stems from improper default file permissions within the installer package. This vulnerability specifically affects versions 4.10.5 and earlier of the Global VPN Client software, creating a pathway for attackers to gain elevated system privileges through manipulation of file permissions. The issue manifests during the installation process where the installer creates files with overly permissive access controls, allowing local users to modify critical system components. This flaw falls under the Common Weakness Enumeration category CWE-276, which specifically addresses incorrect permissions for security-critical resources, making it a direct concern for system integrity and access control mechanisms.
The technical exploitation of this vulnerability occurs when the installer places files in system directories with default permissions that permit modification by non-privileged users. Attackers can leverage this misconfiguration to replace legitimate executable files with malicious binaries, effectively achieving privilege escalation from standard user level to system administrator level. The vulnerability's impact extends beyond simple privilege elevation as it potentially enables full system compromise through command execution capabilities. This type of attack vector aligns with ATT&CK technique T1068, which covers 'Local Privilege Escalation' through the exploitation of system-level weaknesses in software installation processes. The compromised installer creates a persistent backdoor mechanism that can be leveraged for ongoing system access and data exfiltration.
The operational impact of CVE-2021-20037 is particularly severe in enterprise environments where multiple users may have access to systems running affected SonicWall VPN client versions. Organizations deploying these clients face potential data breaches, system compromise, and unauthorized access to sensitive network resources. The vulnerability's persistence across both 32-bit and 64-bit installer versions indicates a systemic flaw in the software's installation methodology rather than a platform-specific issue. Security teams must consider this vulnerability as part of broader endpoint protection strategies, particularly when assessing the risk of insider threats or compromised user accounts that could be exploited to gain system-level access. The vulnerability's exploitation potential makes it a high-priority target for attackers seeking persistent access to corporate networks through legitimate software installation paths.
Mitigation strategies for CVE-2021-20037 primarily involve immediate software updates to versions that address the improper file permission handling during installation. Organizations should implement comprehensive patch management protocols to ensure all affected systems receive the necessary updates promptly. Network administrators should conduct thorough vulnerability assessments to identify all systems running impacted SonicWall client versions and prioritize remediation efforts accordingly. Additional protective measures include implementing strict access controls for system directories, monitoring file permission changes, and establishing robust endpoint detection capabilities. The vulnerability underscores the importance of secure software installation practices and proper privilege management, aligning with security frameworks that emphasize the principle of least privilege and secure configuration management. Organizations should also consider implementing application whitelisting policies to prevent unauthorized modification of critical system components and maintain continuous monitoring for signs of exploitation attempts.