CVE-2018-20939 in cPanel
Summary
by MITRE
cPanel before 68.0.27 allows a user to discover contents of directories (that are not owned by that user) by leveraging backups (SEC-339).
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 07/18/2020
This vulnerability exists in cPanel versions prior to 68.0.27 and represents a critical directory traversal and information disclosure flaw that allows authenticated users to access files and directories they should not normally be able to view. The issue stems from improper access controls within the backup functionality of the cPanel management interface, where users can manipulate backup operations to enumerate and retrieve contents of directories belonging to other users on the same system. The vulnerability specifically affects the backup and restore mechanisms that are commonly used for system maintenance and data recovery purposes, creating a significant security risk when users can bypass normal file system permissions and access restricted content.
The technical implementation of this vulnerability occurs through the backup module's handling of file paths and directory structures during backup operations. When a user initiates a backup process or interacts with backup-related functions, the system fails to properly validate or sanitize the paths being accessed, allowing malicious users to construct backup requests that traverse directory structures beyond their intended scope. This flaw enables attackers to discover file listings, access sensitive configuration files, and potentially extract data from other user accounts that would normally be protected by standard Unix file permissions and ownership models. The vulnerability is particularly dangerous because it operates within the legitimate backup functionality of the system, making it harder to detect and distinguish from normal administrative operations.
The operational impact of this vulnerability extends beyond simple information disclosure to encompass potential data breaches and privilege escalation scenarios. An attacker with access to a low-privilege cPanel account could leverage this vulnerability to discover other user accounts, access sensitive files such as database credentials, configuration files, or personal data, and potentially gain insights that could be used for further attacks. This weakness directly violates the principle of least privilege and can enable attackers to map the entire file system structure of a server, identify vulnerable applications, and discover other security misconfigurations. The vulnerability affects the integrity and confidentiality of the entire hosting environment, as it allows unauthorized access to data that should remain isolated between different user accounts.
Security mitigations for this vulnerability include immediately upgrading to cPanel version 68.0.27 or later, which contains the necessary patches to address the access control bypass in backup operations. System administrators should also implement additional monitoring of backup-related activities and access patterns, particularly when users perform operations that involve directory enumeration or file access outside their normal scope. Organizations should review and tighten access controls for backup functionality, ensure proper user account segregation, and implement network-level controls to limit access to cPanel interfaces. The vulnerability aligns with CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) and can be categorized under ATT&CK technique T1083 (File and Directory Discovery) and T1566 (Phishing). Organizations should also consider implementing automated security scanning tools that can detect anomalous backup activity patterns and alert on potential exploitation attempts. Regular security audits of backup and restore functionality should be conducted to ensure that proper access controls remain in place and that no similar path traversal vulnerabilities exist in other system components.