CVE-2018-20924 in cPanel
Summary
by MITRE
cPanel before 70.0.23 allows arbitrary file-read and file-unlink operations via WHM style uploads (SEC-378).
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Analysis
by VulDB Data Team • 07/18/2020
The vulnerability identified as CVE-2018-20924 affects cPanel versions prior to 70.0.23 and represents a critical security flaw that enables unauthorized file read and unlink operations through WHM style uploads. This vulnerability specifically targets the administrative upload functionality within the WHM (Web Host Manager) interface, which is commonly used by system administrators to manage hosting environments. The flaw arises from inadequate input validation and access control mechanisms that fail to properly sanitize user-supplied data during file upload processes. Security researchers have classified this issue as a directory traversal vulnerability, allowing attackers to manipulate file paths and gain access to sensitive system files that should normally be restricted to authorized personnel only.
The technical implementation of this vulnerability stems from improper handling of file upload parameters within the WHM administrative interface. When administrators upload files through the WHM style upload mechanism, the system fails to adequately validate the destination paths and file names provided by users. This lack of proper validation creates an opportunity for attackers to manipulate the upload process and specify arbitrary file paths that can result in reading sensitive files from the server filesystem or deleting critical system files. The vulnerability is particularly dangerous because it operates within the administrative context, meaning that successful exploitation could provide attackers with elevated privileges and access to the underlying server infrastructure. This flaw aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal vulnerabilities. The attack vector specifically targets the WHM upload functionality, making it accessible through the web-based administrative interface without requiring direct system access.
The operational impact of CVE-2018-20924 extends beyond simple data theft, as it can lead to complete system compromise and unauthorized access to sensitive customer data. Attackers exploiting this vulnerability could read configuration files, database credentials, user account information, and other critical system resources that would normally be protected. The ability to perform unlink operations further amplifies the damage potential, as adversaries could delete important system files, corrupt data, or disrupt services entirely. This vulnerability directly impacts the principle of least privilege and can enable attackers to escalate their privileges within the hosting environment. Organizations using affected cPanel versions face significant risks including data breaches, service disruption, and potential compliance violations under various regulatory frameworks such as gdpr, hipaa, and pci dss standards. The vulnerability also provides attackers with opportunities to establish persistent access through the manipulation of system files, potentially leading to long-term compromise of hosting environments.
Mitigation strategies for CVE-2018-20924 primarily focus on immediate system updates and administrative controls. Organizations should immediately upgrade to cPanel version 70.0.23 or later, which includes patches specifically designed to address the improper input validation and path handling issues. System administrators should also implement additional security measures including restricting access to WHM administrative interfaces through firewall rules, implementing multi-factor authentication for administrative accounts, and monitoring upload activities for suspicious patterns. Network segmentation and access control lists should be configured to limit direct access to administrative interfaces from untrusted networks. The vulnerability demonstrates the importance of proper input validation and access control enforcement, principles that align with ATT&CK framework techniques T1078 and T1068 which cover legitimate credentials and exploit public-facing applications respectively. Regular security audits and vulnerability assessments should be conducted to identify similar issues in other components of the hosting infrastructure, while log monitoring should be enhanced to detect unauthorized file access attempts and suspicious upload activities. Organizations should also consider implementing web application firewalls and intrusion detection systems to provide additional layers of protection against exploitation attempts.