CVE-2018-20131 in Code42 for Enterprise
Summary
by MITRE
The Code42 app before 6.8.4, as used in Code42 for Enterprise, on Linux installs with overly permissive permissions on the /usr/local/crashplan/log directory. This allows a user to manipulate symbolic links to escalate privileges, or show the contents of sensitive files that a regular user would not have access to.
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Analysis
by VulDB Data Team • 04/25/2020
The vulnerability identified as CVE-2018-20131 represents a critical privilege escalation flaw within the Code42 Enterprise backup solution, specifically affecting versions prior to 6.8.4 on Linux systems. This issue stems from improper file system permissions assigned to the crashplan log directory during installation, creating a pathway for unauthorized users to gain elevated system privileges. The flaw exists in the application's installation process where the /usr/local/crashplan/log directory is configured with overly permissive access controls that exceed the minimum required permissions for normal operation. The vulnerability is particularly concerning because it directly impacts the security model of the enterprise backup solution, potentially allowing malicious actors or compromised user accounts to escalate their privileges beyond what is normally permitted.
The technical exploitation of this vulnerability relies on the ability of a regular user to manipulate symbolic links within the improperly configured log directory. This type of attack leverages the principle of least privilege violation, where the system's access controls are insufficient to prevent unauthorized file access or manipulation. The flaw can be categorized under CWE-732: Incorrect Permission Assignment for Critical Resources, which specifically addresses cases where critical system resources are assigned incorrect permissions that allow unauthorized access or modification. When a user can manipulate symbolic links in the log directory, they can potentially redirect file operations to sensitive system files or directories that should normally be restricted to privileged users only. This creates a scenario where a standard user could gain access to sensitive information or execute operations that would typically require root or administrative privileges.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can expose sensitive data that may include system configuration details, user credentials, or other confidential information stored within the application's log files. The ability to read sensitive files through this vector represents a significant data exposure risk that could lead to further exploitation or compromise of the entire system. Attackers could potentially use this vulnerability as a foothold to escalate their access further within the system, or to extract valuable information that could be used for additional attacks. This vulnerability affects organizations that rely on Code42 for Enterprise backup solutions, particularly those with multiple users who may not require full system access but could potentially exploit this flaw to gain elevated privileges. The impact is especially severe in environments where the application runs with elevated privileges during installation or operation, as the vulnerability can be exploited by any user with access to the system.
Mitigation strategies for CVE-2018-20131 require immediate implementation of the vendor-provided patch version 6.8.4 or later, which properly configures the log directory permissions to prevent symbolic link manipulation. System administrators should also conduct comprehensive permission audits of the crashplan installation directories, ensuring that only authorized users or processes have access to sensitive system resources. The recommended approach includes verifying that the /usr/local/crashplan/log directory and its contents are owned by the appropriate system user with minimal required permissions, typically restricting write access to the application process itself. Organizations should also implement monitoring for unusual file system activity in the crashplan directories and consider implementing additional security controls such as file integrity monitoring to detect unauthorized changes to critical system files. From an operational security perspective, this vulnerability highlights the importance of proper access control implementation and regular security assessments of enterprise applications, particularly those with elevated privileges during installation or operation, aligning with ATT&CK technique T1068: Exploitation for Privilege Escalation which specifically addresses methods used to gain higher-level privileges through system vulnerabilities.