CVE-2017-18433 in cPanel
Summary
by MITRE
cPanel before 64.0.21 allows code execution by webmail and demo accounts via a store_filter API call (SEC-236).
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Analysis
by VulDB Data Team • 07/19/2020
The vulnerability identified as CVE-2017-18433 represents a critical code execution flaw within cPanel software versions prior to 64.0.21. This security weakness specifically affects webmail and demo accounts, creating a significant attack surface that could be exploited by malicious actors to gain unauthorized system access. The vulnerability stems from insufficient input validation within the store_filter API call, which processes user-supplied data without proper sanitization or authorization checks.
The technical implementation of this flaw involves the store_filter API endpoint failing to properly validate or sanitize user input parameters before processing them within the system. When webmail and demo accounts make API calls to this endpoint, the system accepts potentially malicious input that can be interpreted as executable code. This represents a classic command injection vulnerability where user-controlled data is directly incorporated into system commands without proper escaping or filtering mechanisms. The vulnerability falls under CWE-77 and CWE-94 categories, which respectively address command injection and code injection flaws that allow attackers to execute arbitrary code on the target system.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with the ability to execute arbitrary commands with the privileges of the webmail or demo accounts. These accounts typically have limited system access but can be leveraged to gain deeper system control through the code execution capability. Attackers could potentially use this vulnerability to install backdoors, exfiltrate sensitive data, modify system configurations, or establish persistent access to the compromised system. The exploitation of this vulnerability directly aligns with ATT&CK technique T1059, which covers command and scripting interpreter, and T1078, which addresses valid accounts for maintaining access.
Organizations running affected cPanel versions face significant risk exposure, particularly those with webmail or demo account functionality enabled. The vulnerability's impact is amplified by the fact that these accounts are often less strictly monitored than regular user accounts, making them attractive targets for attackers seeking initial access. The attack vector requires minimal privileges to exploit, as the vulnerability exists within the API handling mechanism that is accessible to webmail and demo users. Security teams should immediately prioritize patching affected systems, as the vulnerability provides a direct path to system compromise without requiring additional authentication or privilege escalation techniques.
The recommended mitigation strategy involves upgrading to cPanel version 64.0.21 or later, which includes proper input validation and sanitization for the store_filter API endpoint. Additionally, implementing network-level restrictions to limit API access from untrusted networks, monitoring API call patterns for suspicious activity, and conducting regular security assessments of webmail and demo account configurations can help reduce the attack surface. Organizations should also consider implementing application firewalls or web application firewalls to detect and prevent exploitation attempts targeting this specific vulnerability. Regular vulnerability scanning and penetration testing should be conducted to identify similar weaknesses in other system components that might provide similar attack vectors for code execution.