The vulnerability in PluckCMS 4.7.10 is an unrestricted file upload flaw that enables authenticated attackers with admin privileges to restore files from the trash directory without proper validation of file extensions. The exploit leverages the trash_restoreitem action in admin.php, where an attacker sends a crafted HTTP GET request specifying a malicious file with a double extension (e.g., exploit.php.jpg) that was previously uploaded and then deleted (moved to trash). Because the server does not filter double extensions during upload or trash operations, the attacker can restore the malicious file to an accessible location and execute arbitrary commands via web requests (e.g., by accessing exploit_copy.php with command parameters). The attack requires a valid PHP session cookie, meaning the attacker must be authenticated as an admin user. The vulnerability is tracked as CVE-2020-20969 and was tested on Windows environments. The exploit demonstrates how insufficient validation and improper handling of file uploads and trash restoration can lead to remote code execution. Although no widespread exploitation is reported, the presence of public exploit code increases the risk of targeted attacks. The flaw affects the confidentiality and integrity of affected systems by allowing arbitrary code execution and potential full system compromise. The lack of patch links suggests that organizations must seek updates from the vendor or apply custom mitigations. This vulnerability is particularly relevant for web servers hosting PluckCMS-based sites, where administrative interfaces are exposed or accessible by multiple users.

For European organizations, this vulnerability can lead to unauthorized remote code execution on web servers running PluckCMS 4.7.10, compromising sensitive data confidentiality and system integrity. Attackers with admin credentials can upload and restore malicious files, potentially gaining full control over the affected web server. This can result in data breaches, defacement, service disruption, or use of the compromised server as a pivot point for further attacks within the network. Organizations in sectors such as government, finance, healthcare, and media that rely on PluckCMS for content management face increased risks of reputational damage and regulatory penalties under GDPR if personal data is exposed. The requirement for authenticated access limits exploitation to insiders or attackers who have compromised credentials, but phishing or credential stuffing attacks could facilitate this. The medium severity rating reflects the need for administrative access but also the high impact of successful exploitation. The availability of public exploit code lowers the barrier for attackers to develop weaponized payloads. European entities with public-facing PluckCMS admin portals are particularly vulnerable to targeted attacks. The lack of a vendor patch at the time of disclosure increases exposure duration.

1. Immediately restrict access to the PluckCMS administrative interface using network-level controls such as VPNs, IP whitelisting, or multi-factor authentication to reduce the risk of credential compromise. 2. Monitor and audit admin user sessions and file upload activities for suspicious behavior, including unexpected file restorations from the trash directory. 3. Apply any available vendor patches or updates addressing CVE-2020-20969 as soon as they are released. 4. If patches are unavailable, implement custom server-side validation to reject files with double extensions or suspicious file names during upload and trash restore operations. 5. Harden web server configurations to prevent execution of files in upload directories, e.g., by disabling PHP execution in upload folders via .htaccess or equivalent. 6. Educate administrators on secure credential management and phishing awareness to prevent session hijacking. 7. Regularly backup website data and configurations to enable rapid recovery in case of compromise. 8. Employ web application firewalls (WAFs) with rules to detect and block suspicious admin.php requests related to trash_restoreitem actions. 9. Conduct penetration testing and code reviews focusing on file upload and restoration functionalities to identify and remediate similar vulnerabilities.