CVE-2018-17876 in Coast
Summary
by MITRE
A Stored XSS vulnerability has been discovered in the v5.5.0 version of the Coaster CMS product.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 05/22/2023
The vulnerability CVE-2018-17876 represents a critical stored cross-site scripting flaw within the Coaster CMS v5.5.0 software, exposing web applications to persistent malicious code execution. This vulnerability specifically affects the content management system's handling of user input within its administrative interface, where user-supplied data is not properly sanitized before being stored in the database and subsequently rendered in web pages. The flaw allows authenticated attackers with sufficient privileges to inject malicious JavaScript code into the CMS's content management system, which then gets executed whenever other users access the affected pages. This type of vulnerability falls under CWE-79 which categorizes cross-site scripting flaws as weaknesses in input validation and output encoding, representing a fundamental security gap in web application data handling. The vulnerability enables attackers to establish persistent backdoors within the CMS environment, potentially leading to complete system compromise and unauthorized access to sensitive data.
The technical implementation of this stored XSS vulnerability occurs when administrators or users with content editing capabilities submit malicious payloads through the CMS's content creation or editing forms. These payloads are stored in the database without proper sanitization or encoding, and then retrieved and rendered in subsequent page requests without adequate protection mechanisms. When other users or administrators view the affected content, the malicious JavaScript code executes in their browsers, potentially stealing session cookies, redirecting users to malicious sites, or performing unauthorized actions within the CMS. The vulnerability's impact is amplified by the fact that it requires only a single successful injection to persist across multiple user sessions, making it particularly dangerous for content management systems where multiple administrators may access the same content. This aligns with ATT&CK technique T1566.001 which covers the use of malicious content delivery methods to gain initial access, and T1059.007 which addresses the execution of scripts through web applications.
The operational impact of CVE-2018-17876 extends beyond simple data theft, as it enables attackers to manipulate the CMS environment and potentially establish long-term persistence within the target organization's infrastructure. Successful exploitation allows threat actors to modify content, create new administrative accounts, or even deploy additional malware through the compromised CMS interface. The vulnerability affects the integrity and availability of the content management system, potentially causing service disruption while simultaneously providing attackers with a foothold for further reconnaissance and lateral movement within the network. Organizations using Coaster CMS v5.5.0 face significant risk of unauthorized content modification, data exfiltration, and potential complete system takeover. The vulnerability's presence in the administrative interface means that attackers who gain access to legitimate user credentials can leverage this flaw to execute persistent attacks without requiring additional authentication mechanisms. This makes the vulnerability particularly concerning for organizations that rely heavily on CMS functionality for their web presence and content management operations.
Mitigation strategies for CVE-2018-17876 require immediate action including upgrading to a patched version of Coaster CMS that addresses the stored XSS vulnerability through proper input sanitization and output encoding mechanisms. Organizations should implement comprehensive content security policies that enforce strict validation of all user-supplied data before storage, utilizing libraries and frameworks that automatically escape or encode potentially dangerous characters. Network segmentation and access control measures should be strengthened to limit administrative privileges and reduce the attack surface available to potential attackers. Regular security auditing and penetration testing of CMS environments should be conducted to identify similar vulnerabilities, while implementing web application firewalls to detect and block malicious payloads. The remediation process must include thorough testing of all CMS components to ensure that the patch does not introduce regressions in functionality, and that proper logging and monitoring mechanisms are in place to detect potential exploitation attempts. Additionally, organizations should establish incident response procedures specifically tailored to handle CMS-based security incidents, ensuring rapid identification and containment of any exploitation attempts that may occur.