CVE-2017-18384 in cPanel
Summary
by MITRE
cPanel before 68.0.15 allows jailed accounts to restore files that are outside of the jail (SEC-310).
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 07/18/2020
The vulnerability identified as CVE-2017-18384 affects cPanel versions prior to 68.0.15 and represents a critical access control flaw that undermines the fundamental security boundaries of jailed accounts. This issue stems from insufficient input validation and path traversal mechanisms within the file restoration functionality of the cPanel control panel, which is widely used by hosting providers and system administrators to manage multiple user accounts on shared servers. The vulnerability specifically targets the jail environment that cPanel implements to isolate user accounts and prevent unauthorized access to other users' files or system resources.
The technical flaw manifests when a malicious user with access to a jailed account attempts to restore files using the cPanel restoration feature. Due to inadequate sanitization of file paths and restoration parameters, the system fails to properly validate whether the target restoration location falls within the designated jail boundaries. This allows an attacker to specify absolute paths or manipulate directory traversal sequences that bypass the intended confinement mechanisms. The vulnerability is categorized under CWE-22 as a Path Traversal attack, where the system does not properly restrict access to files outside of the intended directory structure. Attackers can exploit this weakness to restore files to arbitrary locations on the filesystem, potentially overwriting critical system files or gaining access to data belonging to other users on the same hosting platform.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it fundamentally compromises the security model that cPanel relies upon to maintain isolation between user accounts. When an attacker successfully exploits this flaw, they can restore malicious files to system directories, potentially leading to privilege escalation, persistent backdoors, or complete system compromise. The vulnerability is particularly dangerous in shared hosting environments where multiple customers share the same physical server, as it enables one compromised account to affect the integrity and security of other accounts. From an attacker's perspective, this vulnerability aligns with ATT&CK technique T1059.001 for command and scripting interpreter, and T1078.004 for valid accounts, as it allows exploitation of legitimate account access to achieve unauthorized system modifications. The impact is further amplified by the fact that cPanel administrators often grant jailed accounts with certain administrative privileges, making the restoration functionality particularly dangerous when misused.
Mitigation strategies for CVE-2017-18384 must prioritize immediate patching of affected cPanel installations to version 68.0.15 or later, which includes proper input validation and path sanitization mechanisms. System administrators should implement additional monitoring of file restoration activities, particularly those involving absolute paths or unusual directory traversals, to detect potential exploitation attempts. The security model should be enhanced through stricter enforcement of jail boundaries using filesystem permissions and mandatory access controls. Organizations should also consider implementing network-based intrusion detection systems to monitor for suspicious restoration activities and ensure that regular security audits verify proper enforcement of account isolation. The vulnerability underscores the importance of proper input validation and access control mechanisms in multi-tenant environments, as highlighted by security frameworks that emphasize the need for defense in depth and principle of least privilege in shared hosting scenarios.