CVE-2016-10855 in cPanel
Summary
by MITRE
cPanel before 11.54.0.4 allows unauthenticated arbitrary code execution via cpsrvd (SEC-91).
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Analysis
by VulDB Data Team • 11/20/2023
The vulnerability identified as CVE-2016-10855 represents a critical security flaw in cPanel software versions prior to 11.54.0.4 that enables unauthenticated arbitrary code execution through the cpsrvd service. This vulnerability falls under the category of remote code execution flaws that can be exploited without requiring any authentication credentials, making it particularly dangerous for web hosting environments where cPanel is deployed. The vulnerability specifically affects the cpsrvd daemon which serves as the core service responsible for handling administrative operations within cPanel.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the cpsrvd service. Attackers can craft malicious requests that bypass authentication mechanisms and directly execute arbitrary commands on the underlying server. This flaw operates at the application level and can be exploited through network-based attacks, allowing remote threat actors to gain complete control over the affected system. The vulnerability is categorized under CWE-20, which represents "Improper Input Validation" and aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter, indicating the ability to execute commands through the compromised service.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete system compromise capabilities. Once exploited, adversaries can install backdoors, exfiltrate sensitive data, modify system configurations, and establish persistent access to the hosting environment. This vulnerability particularly affects shared hosting environments where multiple customers may be hosted on the same server, potentially allowing attackers to compromise not just one account but entire hosting platforms. The unauthenticated nature of the exploit means that any network-accessible cPanel installation running vulnerable versions is immediately at risk without requiring additional reconnaissance or credential acquisition.
Organizations affected by this vulnerability should prioritize immediate patching of all cPanel installations to version 11.54.0.4 or later. The mitigation strategy should include comprehensive network monitoring to detect potential exploitation attempts and implementation of network segmentation to limit access to administrative services. Additional defensive measures include deploying web application firewalls to filter suspicious requests, implementing strict access controls for cpsrvd service ports, and conducting regular security assessments of hosting environments. Security teams should also monitor for indicators of compromise such as unusual command execution patterns, unauthorized access logs, and unexpected network connections from compromised systems. The vulnerability demonstrates the critical importance of maintaining up-to-date software versions and implementing layered security approaches in hosting environments where multiple customers share system resources.