CVE-2017-18481 in cPanel
Summary
by MITRE
cPanel before 62.0.4 allows stored XSS in the WHM Account Suspension List interface (SEC-211).
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Analysis
by VulDB Data Team • 07/21/2020
The vulnerability identified as CVE-2017-18481 affects cPanel versions prior to 62.0.4 and represents a stored cross-site scripting flaw within the WHM Account Suspension List interface. This security weakness falls under the category of persistent XSS attacks where malicious input is stored on the server and subsequently executed when users access the affected interface. The vulnerability specifically resides in the WHM (Web Host Manager) component of cPanel, which provides administrative capabilities for hosting environments. The affected interface processes user-supplied data without adequate sanitization or output encoding, creating an avenue for attackers to inject malicious scripts that persist across user sessions.
The technical implementation of this vulnerability stems from insufficient input validation and output sanitization mechanisms within the WHM Account Suspension List functionality. When administrators or users interact with this interface, the system fails to properly escape or filter special characters from input fields that are later rendered in the web interface. This allows attackers to inject malicious javascript code through account suspension parameters or related data fields. The stored nature of this vulnerability means that once malicious input is submitted and processed, it remains persistent in the system until explicitly removed, making it particularly dangerous as it can affect multiple users who access the vulnerable interface. This flaw aligns with CWE-79 which categorizes cross-site scripting vulnerabilities, specifically addressing the storage of malicious code that can be executed in the context of other users' browsers.
The operational impact of CVE-2017-18481 extends beyond simple data theft or defacement, as it can enable attackers to perform privilege escalation, session hijacking, and unauthorized administrative actions within the compromised hosting environment. An attacker who successfully exploits this vulnerability could potentially gain access to sensitive account information, manipulate suspension statuses, or execute commands with elevated privileges depending on the victim's role within the cPanel environment. The attack vector requires minimal user interaction beyond accessing the vulnerable interface, making it particularly effective for targeting system administrators who regularly monitor account suspensions. This vulnerability can be exploited through various means including social engineering campaigns that trick administrators into clicking malicious links or through automated scanning tools that identify the vulnerable interface. The persistent nature of stored XSS makes it particularly concerning for environments where multiple administrators access the same WHM interface, as the malicious payload can affect all subsequent users who view the compromised account suspension list.
Mitigation strategies for CVE-2017-18481 primarily focus on upgrading to cPanel version 62.0.4 or later, which includes the necessary patches to address the input validation and output encoding deficiencies. Organizations should implement comprehensive patch management procedures to ensure all cPanel installations remain current with security updates. Additional defensive measures include implementing web application firewalls that can detect and block suspicious script injection attempts, conducting regular security audits of web interfaces, and establishing strict input validation policies for all user-supplied data. Network segmentation and privileged access controls can help limit the potential damage if exploitation occurs, while regular monitoring of the WHM interface for unusual activity patterns can aid in early detection of attempted exploitation. The vulnerability also highlights the importance of following security best practices such as the principle of least privilege, regular security training for administrators, and maintaining detailed audit logs of administrative activities. Organizations should also consider implementing automated vulnerability scanning tools that can identify similar stored XSS vulnerabilities in other web applications within their infrastructure. The remediation process should include thorough testing of the patched environment to ensure that the security fix does not introduce compatibility issues with existing hosting configurations or administrative workflows. Security teams should also review their incident response procedures to ensure readiness for potential exploitation of this type of vulnerability, particularly given its relevance to the attack technique described in the ATT&CK framework under the T1059.007 sub-technique for scripting and T1566 for social engineering attacks that commonly leverage stored XSS vulnerabilities.