CVE-2016-10771 in cPanel
Summary
by MITRE
cPanel before 60.0.25 allows file-create and file-chmod operations during ModSecurity Audit logfile processing (SEC-165).
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Analysis
by VulDB Data Team • 07/20/2020
The vulnerability identified as CVE-2016-10771 affects cPanel versions prior to 60.0.25 and represents a significant security flaw in the ModSecurity audit log processing functionality. This issue arises from insufficient input validation and privilege escalation during the handling of audit log files, creating a pathway for malicious actors to manipulate file system operations within the cPanel environment. The vulnerability specifically impacts the security mechanisms that are designed to monitor and log web application attacks, inadvertently allowing unauthorized file creation and modification operations.
The technical flaw stems from the improper handling of ModSecurity audit log files where cPanel processes these logs without adequate sanitization of user-supplied data. When ModSecurity generates audit logs containing potentially malicious input, the cPanel system fails to properly validate or escape this data before using it in file system operations. This creates a scenario where an attacker can inject malicious file creation or permission change commands through the audit log processing pipeline, effectively bypassing normal file system access controls. The vulnerability is particularly dangerous because it operates within the security monitoring framework itself, making detection more difficult and exploitation more impactful.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it allows attackers to establish persistent access mechanisms within compromised cPanel environments. An attacker could create malicious files with specific permissions, potentially establishing backdoors or other persistent threats that survive system restarts. The file-chmod operations enable attackers to modify existing file permissions, potentially elevating privileges or disabling security controls. This vulnerability affects the integrity and confidentiality of web hosting environments, as attackers can manipulate the very security tools designed to protect them. The flaw represents a critical weakness in the principle of least privilege, where audit logging functionality becomes a vector for privilege escalation.
Mitigation strategies for CVE-2016-10771 require immediate patching of cPanel installations to version 60.0.25 or later, which includes proper input sanitization and validation for ModSecurity audit log processing. Organizations should implement additional monitoring of file system changes during audit log processing and establish automated alerts for suspicious file creation or permission modifications. The vulnerability aligns with CWE-20 Improper Input Validation and CWE-78 Improper Neutralization of Special Elements used in OS Commands, representing a classic case of command injection through inadequate input sanitization. From an ATT&CK framework perspective, this vulnerability maps to T1059 Command and Scripting Interpreter and T1078 Valid Accounts, as it enables attackers to execute commands and potentially maintain access through file system manipulation. Network segmentation and limiting access to ModSecurity audit log processing functions can provide additional defensive layers, while regular security audits should verify that no unauthorized modifications have occurred in affected systems.