CVE-2018-18307 in AlchemyCMS
Summary
by MITRE
A Stored XSS vulnerability has been discovered in version 4.1.0 of AlchemyCMS via the /admin/pictures image field.
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Analysis
by VulDB Data Team • 08/05/2024
The vulnerability CVE-2018-18307 represents a critical stored cross-site scripting flaw within AlchemyCMS version 4.1.0 that specifically targets the administrative picture upload functionality. This issue arises when users with administrative privileges upload images through the /admin/pictures endpoint, creating a persistent security risk that can affect all users interacting with the compromised system. The vulnerability stems from insufficient input validation and output sanitization mechanisms within the content management platform's image handling process.
The technical implementation of this flaw occurs when maliciously crafted image metadata or file names containing script tags are uploaded to the system. The application fails to properly sanitize user-supplied data before storing and subsequently rendering it within the web interface. When other users access the administrative panel or view pages containing the compromised images, the embedded malicious scripts execute in their browsers, potentially leading to session hijacking, data exfiltration, or further exploitation. This stored nature of the vulnerability means that the malicious payload persists even after the initial upload, making it particularly dangerous for long-term compromise.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with a persistent foothold within the administrative environment. Attackers can leverage this vulnerability to escalate privileges, modify content, steal administrative sessions, or redirect users to malicious sites. The vulnerability directly violates security principles outlined in CWE-79, which addresses cross-site scripting flaws, and aligns with ATT&CK technique T1059.001 for command and scripting interpreter. The attack surface is particularly concerning given that the vulnerability exists within the core administrative upload functionality, making it accessible to any authenticated user with upload privileges.
Mitigation strategies for this vulnerability should include immediate patching of the AlchemyCMS application to version 4.1.1 or later, which contains the necessary security fixes. Organizations should implement strict input validation and output encoding for all user-supplied data, particularly within file upload contexts. Additional protective measures include implementing Content Security Policy headers, conducting regular security audits of uploaded content, and establishing proper access controls for administrative functions. Security monitoring should focus on identifying unusual upload patterns or attempts to embed malicious content within image files, as outlined in the NIST Cybersecurity Framework's protective safeguards. Organizations should also consider implementing web application firewalls to detect and block known XSS attack patterns targeting similar vulnerabilities in content management systems.