CVE-2018-20910 in cPanel
Summary
by MITRE
cPanel before 70.0.23 allows self XSS in the WHM cPAddons showsecurity Interface (SEC-357).
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Analysis
by VulDB Data Team • 07/18/2020
The vulnerability identified as CVE-2018-20910 represents a critical self-cross-site scripting flaw within the cPanel WHM cPAddons showsecurity interface. This security issue affects cPanel versions prior to 70.0.23 and specifically targets the administrative interface used for managing addon domains and security configurations. The vulnerability stems from inadequate input validation and output encoding mechanisms within the WHM administrative panel's cPAddons component, creating an exploitable condition where malicious actors can inject malicious scripts into the interface. The flaw operates through the showsecurity functionality which displays security information related to addon domains, making it a prime target for attackers seeking to compromise administrative sessions.
The technical implementation of this vulnerability involves the improper handling of user-supplied data within the WHM interface, particularly when displaying security information related to addon domains. When administrators interact with the cPAddons showsecurity interface, the system fails to properly sanitize or encode input parameters that are subsequently rendered in the browser context. This allows an attacker who has access to the cPanel administrative interface to craft malicious payloads that exploit the self-XSS condition, potentially enabling session hijacking or privilege escalation attacks. The vulnerability operates under CWE-79 which specifically addresses cross-site scripting flaws, and can be categorized under ATT&CK technique T1059.001 for command and scripting interpreter, as attackers may leverage the interface to execute malicious commands through the XSS payload.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to escalate privileges within the cPanel administrative environment. Once an attacker successfully exploits the self-XSS condition, they can potentially execute malicious scripts that steal administrative session cookies, redirect users to malicious sites, or manipulate the administrative interface to perform unauthorized actions. The self-XSS nature means that the malicious payload is executed within the context of the authenticated administrator's browser session, making it particularly dangerous for organizations relying on cPanel for hosting management. This vulnerability can lead to complete compromise of hosting environments, allowing attackers to manage domains, modify configurations, and potentially access sensitive customer data. Organizations using older cPanel versions without proper security updates are particularly vulnerable to this type of attack vector.
Mitigation strategies for CVE-2018-20910 primarily focus on immediate patching and security hardening measures. The most effective remediation involves upgrading cPanel to version 70.0.23 or later, which includes proper input validation and output encoding fixes for the affected interface. Organizations should implement regular security patch management processes to ensure all administrative interfaces remain up-to-date with the latest security releases. Additional protective measures include implementing proper input validation at multiple layers, enforcing strict output encoding for all dynamic content rendered in administrative interfaces, and conducting regular security assessments of administrative panels. Network segmentation and monitoring of administrative access logs can help detect potential exploitation attempts. The vulnerability also highlights the importance of maintaining security awareness training for administrators and implementing principle of least privilege access controls to limit the potential impact of successful exploitation attempts. Security teams should also consider implementing web application firewalls and content security policies to provide additional protection against similar XSS vulnerabilities in administrative interfaces.