CVE-2017-18462 in cPanel
Summary
by MITRE
cPanel before 62.0.17 allows a CPHulk one-day ban bypass when IP based protection is enabled (SEC-224).
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Analysis
by VulDB Data Team • 07/20/2020
The vulnerability CVE-2017-18462 represents a critical security flaw in cPanel versions prior to 62.0.17 that affects the CPHulk brute force protection system. This issue specifically targets the one-day ban mechanism designed to prevent unauthorized access attempts by temporarily blocking IP addresses that exceed configured threshold limits. The vulnerability allows attackers to circumvent this protection by exploiting a timing window or specific request patterns that bypass the intended IP-based restrictions. The flaw resides in how cPanel handles the enforcement of temporary IP bans within its CPHulk component, which is responsible for monitoring and blocking suspicious login attempts from malicious actors.
The technical implementation of this vulnerability stems from insufficient validation mechanisms within the CPHulk protection framework. When IP-based protection is enabled, the system should maintain strict enforcement of one-day bans, preventing repeated access attempts from identified malicious IP addresses. However, the flaw allows attackers to perform login attempts that either fall outside the scope of the ban enforcement or manipulate the timing of their requests to avoid triggering the proper blocking mechanisms. This bypass typically occurs through the manipulation of session handling, request sequencing, or by exploiting gaps in the enforcement logic that governs how long and under what conditions IP addresses remain blocked.
The operational impact of this vulnerability extends beyond simple access control failures and represents a significant risk to system security. Organizations relying on cPanel for hosting services face potential unauthorized access to user accounts, especially those with weak passwords or shared hosting environments where multiple users exist. The bypass allows attackers to continue brute force attempts against login credentials despite having been temporarily banned, effectively neutralizing the protection measures designed to prevent automated attacks. This can lead to account takeovers, data breaches, and unauthorized access to sensitive customer information stored within the hosting environment.
Mitigation strategies for CVE-2017-18462 require immediate patching of cPanel installations to version 62.0.17 or later, which contains the necessary fixes to properly enforce the one-day ban mechanisms. System administrators should also implement additional monitoring of login attempts and IP address patterns to detect anomalous behavior that might indicate exploitation attempts. Network-level protections such as firewalls and intrusion prevention systems can be configured to limit login attempts from suspicious IP addresses. Organizations should also consider implementing multi-factor authentication as an additional layer of protection, as this vulnerability primarily affects password-based authentication systems. The flaw aligns with CWE-284 access control issues and represents a specific implementation weakness in privilege management systems, potentially mapping to ATT&CK techniques related to credential access and privilege escalation through brute force methods.
This vulnerability demonstrates the critical importance of proper session management and access control enforcement in web applications. The bypass mechanism highlights the need for comprehensive testing of security controls, particularly those designed to prevent automated attacks, and underscores the necessity of maintaining up-to-date security software to protect against known exploitation techniques. Organizations should conduct thorough security assessments of their hosting environments to identify similar vulnerabilities in other security controls and ensure that all protection mechanisms function as intended. Regular security audits and penetration testing can help identify gaps in access control systems that might allow similar bypasses to occur in other components of the hosting infrastructure.