CVE-2018-18741 in SEMCMS
Summary
by MITRE
An XSS issue was discovered in SEMCMS 3.4 via admin/SEMCMS_Download.php?lgid=1 during editing.
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Analysis
by VulDB Data Team • 04/07/2020
The vulnerability identified as CVE-2018-18741 represents a cross-site scripting flaw within SEMCMS version 3.4 that specifically affects the administrative interface through the SEMCMS_Download.php script. This issue arises when an attacker can manipulate the lgid parameter to inject malicious scripts into the web application's response, potentially compromising the administrative session and the overall system security. The vulnerability is classified under CWE-79 as a classic cross-site scripting attack, where untrusted data is improperly incorporated into web page content without proper sanitization or encoding mechanisms. The affected parameter lgid in the admin/SEMCMS_Download.php endpoint demonstrates a failure in input validation that allows attackers to execute arbitrary JavaScript code within the context of the administrative user's browser.
The technical exploitation of this vulnerability occurs through the manipulation of the lgid query parameter which is likely used to specify language identifiers or localization settings within the content management system. When an administrator navigates to the download management page with a crafted lgid value, the application fails to properly sanitize or encode the input before incorporating it into the HTML response. This creates an environment where malicious scripts can be executed in the context of the authenticated administrative session, potentially leading to full system compromise. The vulnerability operates at the application layer and requires minimal privileges to exploit, as it targets the administrative interface rather than requiring elevated system access. This aligns with ATT&CK technique T1059.007 for command and scripting interpreter, where the attacker leverages the administrative session to execute malicious code.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform a wide range of malicious activities including session hijacking, data exfiltration, and privilege escalation. An attacker who successfully exploits this vulnerability could potentially modify content, delete files, create new administrative users, or gain access to sensitive configuration data. The administrative context of the vulnerability makes it particularly dangerous as it provides attackers with elevated privileges within the system. The lack of proper input validation and output encoding represents a fundamental security flaw in the application's security architecture, potentially affecting all users who have administrative access to the SEMCMS system.
Mitigation strategies for CVE-2018-18741 should focus on implementing robust input validation and output encoding mechanisms throughout the application. The most effective immediate solution involves sanitizing all user-supplied input parameters, particularly those used in dynamic content generation, through proper HTML entity encoding or context-appropriate sanitization. Organizations should implement a comprehensive input validation framework that rejects or filters out potentially malicious characters and sequences before processing user input. Additionally, the application should employ Content Security Policy (CSP) headers to prevent execution of unauthorized scripts even if the vulnerability is somehow exploited. Regular security updates and patches should be applied to ensure the CMS is running the latest secure version, as this vulnerability was likely addressed in subsequent releases. The implementation of web application firewalls and security monitoring systems can also help detect and prevent exploitation attempts targeting this specific vulnerability pattern.