CVE-2017-18391 in cPanel
Summary
by MITRE
cPanel before 68.0.15 allows attackers to read backup files because they are world-readable during a short time interval (SEC-323).
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Analysis
by VulDB Data Team • 07/18/2020
The vulnerability identified as CVE-2017-18391 affects cPanel versions prior to 68.0.15 and represents a critical access control flaw that compromises the confidentiality of backup data. This issue stems from improper file permission handling during the backup process, creating a temporal window where backup files are accessible to all system users. The vulnerability was documented as SEC-323 and highlights a fundamental weakness in the backup management system's security posture.
The technical flaw manifests when cPanel generates backup files, which are temporarily stored with world-readable permissions. During this brief interval between backup creation and the application of proper access controls, any user with system access can read these backup files. This temporary exposure occurs because the system does not immediately enforce restrictive permissions on backup files, allowing unauthorized access to potentially sensitive data including configuration files, user credentials, database contents, and application data. The vulnerability is particularly concerning because backup files often contain comprehensive system information that could be exploited for further attacks.
The operational impact of this vulnerability extends beyond simple data exposure, as it provides attackers with a potential pathway for privilege escalation and lateral movement within compromised systems. When backup files contain database credentials, configuration settings, or other sensitive information, attackers can leverage this access to gain deeper insights into the system architecture and potentially access additional compromised systems. This vulnerability directly impacts the principle of least privilege and violates security best practices for data protection. The temporal nature of the exposure means that even brief access windows can be exploited by attackers who monitor system activity or have legitimate access to the system during the vulnerable period.
Mitigation strategies for this vulnerability include immediate upgrading to cPanel version 68.0.15 or later, which implements proper permission handling for backup files. System administrators should also implement additional monitoring to detect unauthorized access to backup directories and consider implementing automated permission enforcement mechanisms. The vulnerability aligns with CWE-276, which addresses improper file permissions, and relates to ATT&CK technique T1213, which covers data from information repositories. Organizations should also review their backup storage configurations and ensure that backup files are immediately protected with appropriate access controls upon creation, following the principle of least privilege and implementing proper security controls throughout the backup lifecycle management process.