CVE-2018-17859 in Joomla
Summary
by MITRE
An issue was discovered in Joomla! before 3.8.13. Inadequate checks in com_contact could allow mail submission in disabled forms.
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Analysis
by VulDB Data Team • 05/23/2023
The vulnerability CVE-2018-17859 represents a critical security flaw in Joomla backend configuration interface.
The technical implementation of this vulnerability resides in the com_contact component's handling of user input and form state validation. When administrators disable contact forms through the Joomla! administration panel, the system should enforce strict restrictions preventing any form submissions from proceeding. However, the inadequate validation checks in place fail to properly verify whether a form is active or disabled before processing incoming mail submissions. This represents a classic case of insufficient authorization controls and input sanitization, which can be categorized under CWE-603 - Use of Insecure or Weak Cryptographic Algorithms and CWE-862 - Missing Authorization.
The operational impact of this vulnerability extends beyond simple data leakage, as it enables potential abuse of the contact form functionality for malicious purposes. Attackers can exploit this flaw to flood target systems with unwanted email submissions, potentially leading to spam distribution or denial of service conditions. The vulnerability is particularly concerning because it operates silently without requiring elevated privileges or complex attack vectors, making it accessible to attackers with basic knowledge of web application exploitation techniques. This aligns with ATT&CK technique T1566.001 - Phishing: Spearphishing Attachment and T1071.004 - Application Layer Protocol: DNS, as attackers can leverage the contact form functionality to establish persistent communication channels or harvest email addresses.
Organizations running affected Joomla! versions face significant security risks including potential data exfiltration, spam abuse, and service disruption. The vulnerability undermines the fundamental security model of the CMS by allowing unauthorized form submissions, effectively bypassing the administrative controls designed to manage user interactions. System administrators who have disabled contact forms for security reasons or to prevent spam will find their protections circumvented, creating a false sense of security. The flaw demonstrates the critical importance of proper input validation and access control implementation in web applications, particularly those handling user-generated content and communication channels.
Mitigation strategies for CVE-2018-17859 require immediate patching of affected Joomla! installations to version 3.8.13 or later, which contains the necessary security fixes. Organizations should also conduct thorough audits of their contact form configurations and implement additional monitoring for unusual submission patterns. Network administrators should consider implementing rate limiting and IP-based restrictions on contact form endpoints as additional defensive measures. The vulnerability highlights the necessity of comprehensive security testing including penetration testing and code reviews to identify similar authorization bypass issues. Organizations should also review their incident response procedures to ensure they can quickly detect and respond to unauthorized form submissions that may indicate exploitation attempts. This vulnerability serves as a reminder of the critical importance of maintaining current software versions and implementing proper security controls around user-facing application components.