CVE-2018-20898 in cPanel
Summary
by MITRE
cPanel before 71.9980.37 allows e-mail injection during cPAddons moderation (SEC-396).
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Analysis
by VulDB Data Team • 07/18/2020
The vulnerability identified as CVE-2018-20898 affects cPanel versions prior to 71.9980.37 and represents a critical email injection flaw within the cPAddons moderation process. This vulnerability enables malicious actors to inject arbitrary email content when cPanel administrators moderate addon requests, potentially leading to unauthorized email transmission and spoofing attacks. The issue stems from insufficient input validation and sanitization mechanisms during the email handling process within the cPAddons module.
The technical flaw manifests when cPanel administrators review and moderate addon requests through the cPAddons interface. During this moderation process, the system fails to properly sanitize user-supplied email addresses or content that may be included in the moderation workflow. Attackers can exploit this weakness by crafting malicious input that includes email injection sequences such as carriage return and line feed characters, allowing them to inject additional email headers or content into the automated moderation emails. This vulnerability operates under CWE-116, which categorizes improper encoding or escaping of output, and specifically relates to CWE-74, which addresses injection flaws in email headers.
The operational impact of this vulnerability extends beyond simple email manipulation to potentially enable more sophisticated attacks within the cPanel environment. An attacker who successfully exploits this vulnerability could send phishing emails, spam campaigns, or malicious email content to users within the cPanel domain. The attack vector is particularly concerning because it leverages the trust relationship between cPanel administrators and the moderation system, allowing attackers to bypass normal email security controls. This vulnerability could also facilitate social engineering attacks where attackers manipulate the moderation emails to appear legitimate to end users, potentially leading to credential theft or system compromise.
From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1192 (Proxying) and T1566 (Phishing) by enabling unauthorized email injection that can be used for malicious communication. The exploitation process requires minimal privileges and can be executed by any user who has access to the cPAddons moderation interface, making it particularly dangerous in multi-user hosting environments. The vulnerability also intersects with T1078 (Valid Accounts) as it leverages legitimate administrative access to perform unauthorized actions within the email system.
Mitigation strategies for CVE-2018-20898 primarily involve upgrading to cPanel version 71.9980.37 or later, which includes proper input sanitization and validation mechanisms for email content within the cPAddons moderation process. Organizations should also implement additional email security measures including proper email header validation, content filtering, and monitoring for unusual email patterns. Network-level controls such as email gateway filtering and spam detection systems can provide additional layers of protection. Regular security auditing of administrative interfaces and input validation processes should be implemented to prevent similar vulnerabilities from emerging in other components of the cPanel system. System administrators should also consider implementing principle of least privilege access controls for cPAddons moderation functions to limit the potential impact of any successful exploitation attempts.