CVE-2018-20923 in cPanel
Summary
by MITRE
cPanel before 70.0.23 allows stored XSS via a WHM Synchronize DNS Records action (SEC-377).
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Analysis
by VulDB Data Team • 07/18/2020
The vulnerability identified as CVE-2018-20923 represents a critical stored cross-site scripting flaw within cPanel software versions prior to 70.0.23. This vulnerability specifically affects the WHM Synchronize DNS Records functionality, which is a core administrative feature used by system administrators to maintain DNS zone files across multiple servers. The issue stems from insufficient input validation and output sanitization within the web interface where user-supplied data is not properly escaped before being rendered back to users. When administrators perform the DNS synchronization action, malicious input can be stored within the application's database and subsequently executed in the context of other users' browsers who view the affected interface. This vulnerability falls under the CWE-79 category of Cross-Site Scripting and aligns with ATT&CK technique T1211 which involves manipulating applications to execute arbitrary code or commands. The flaw enables attackers to inject malicious scripts that can steal session cookies, perform unauthorized actions on behalf of users, or redirect victims to malicious sites. The impact extends beyond simple data theft as it can facilitate privilege escalation and persistent backdoor access to compromised systems. Attackers can exploit this vulnerability by crafting malicious DNS records or parameters that get processed during the synchronization operation, thereby storing the payload in the application's data stores. The stored nature of this vulnerability means that the malicious code persists even after the initial injection point and can affect multiple users who access the affected administrative interface. This particular vulnerability was classified as SEC-377 by cPanel's security team, indicating its severity and the need for immediate remediation. Organizations using older cPanel versions are particularly at risk as the stored XSS allows for long-term persistence and can be leveraged to establish covert command and control channels. The vulnerability demonstrates the critical importance of input validation in web applications and highlights how seemingly benign administrative functions can become attack vectors when proper security controls are absent. System administrators should immediately upgrade to cPanel version 70.0.23 or later to mitigate this risk, as the update includes proper sanitization measures and input validation controls. Additionally, implementing web application firewalls and monitoring for suspicious DNS synchronization activities can provide additional layers of defense. The vulnerability also underscores the necessity of regular security assessments and prompt patch management to prevent exploitation of known vulnerabilities in widely used administrative interfaces. Organizations should consider implementing security awareness training for administrators to recognize potential social engineering attempts that might leverage such vulnerabilities. The remediation process should include thorough testing of the updated software to ensure that the XSS protection mechanisms function correctly and do not introduce regressions in legitimate administrative functionality. Furthermore, implementing principle of least privilege for administrative accounts and monitoring access logs for unusual DNS synchronization patterns can help detect potential exploitation attempts. This vulnerability exemplifies how security flaws in management interfaces can have far-reaching consequences for entire network infrastructures, making timely patch deployment and comprehensive security monitoring essential practices for maintaining system integrity.