Horizon Alert
Summary of the vulnerability and why it matters
A critical vulnerability in GetSimple CMS allows an authenticated attacker to execute arbitrary code on the web server. This occurs because the update handler processes downloaded archives without properly validating file types or extraction locations, enabling the placement of malicious PHP files in web-accessible directories and potentially allowing directory traversal.
- Attackers can run unauthorized code on servers.
- This issue affects content management systems.
- Confirm relevance and exposure in your environment.
Attack Path
How an attacker could exploit the issue
An attacker with administrative access to GetSimple CMS could upload a specially crafted ZIP archive. This archive, when processed by the update handler, could extract malicious PHP files into a web-accessible directory, leading to remote code execution. The vulnerability also allows directory traversal, enabling the attacker to write files outside the intended extraction location.
- Authenticated administrative access required.
- Malicious archive processed by update handler.
- Remote code execution as web server user.
Live Threat
Current exploitation, exposure, and threat context
When supported by the advisory, the update handler in GetSimple CMS CE could allow an authenticated attacker to achieve remote code execution by uploading a malicious archive. This could occur if the attacker can trigger the update process, leading to PHP files being written into a web-accessible directory, potentially allowing them to execute arbitrary code as the web server user.
- Web server user and files could be at risk.
- Malicious archive upload could enable traversal.
- Remote code execution is a realistic consequence.
Operational Fix
Recommended remediation, mitigation, and detection steps
This vulnerability affects GetSimple CMS, a web-based content management system. Ownership typically resides with the application or platform team responsible for managing the CMS instances. The first actionable step is to identify all deployed GetSimple CMS instances, determine their reachability and criticality, and then confirm the accountable owner for each instance before planning remediation.
- Application or platform team ownership.
- Verify CMS reachability and criticality.
- Plan remediation based on risk.
