CVE-2019-9623 in Feng Office
Summary
by MITRE
Feng Office 3.7.0.5 allows remote attackers to execute arbitrary code via "<!--#exec cmd=" in a .shtml file to ck_upload_handler.php.
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Analysis
by VulDB Data Team • 08/18/2025
The vulnerability identified as CVE-2019-9623 affects Feng Office version 3.7.0.5 and represents a critical remote code execution flaw that stems from inadequate input validation within the ck_upload_handler.php component. This weakness enables attackers to inject malicious server-side includes directives into .shtml files, specifically targeting the exec command functionality that allows arbitrary code execution on the affected system. The vulnerability exists due to insufficient sanitization of file upload parameters, particularly when processing files with the .shtml extension that may contain embedded server-side includes directives.
The technical exploitation of this vulnerability relies on the web application's failure to properly validate and sanitize user-supplied input during file upload operations. When a malicious .shtml file containing the directive <!--#exec cmd=" is uploaded through the ck_upload_handler.php endpoint, the server processes the file without adequate filtering, allowing the embedded command execution directive to be interpreted and executed by the web server. This flaw falls under the CWE-94 category of "Improper Control of Generation of Code ('Code Injection')" and specifically aligns with CWE-74 which addresses "Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')." The vulnerability demonstrates a classic server-side include injection attack vector that bypasses normal input validation mechanisms.
The operational impact of this vulnerability is severe as it provides remote attackers with complete system compromise capabilities. Successful exploitation allows adversaries to execute arbitrary commands with the privileges of the web server process, potentially leading to full system control, data exfiltration, and persistence mechanisms. Attackers can leverage this vulnerability to deploy malware, establish backdoors, or conduct further reconnaissance within the network. The attack surface is particularly concerning as it requires minimal privileges to exploit and can be automated through web-based attack frameworks. This vulnerability directly maps to ATT&CK technique T1059.007 for "Command and Scripting Interpreter: Unix Shell" and T1078.004 for "Valid Accounts: Cloud Accounts" when considering the potential for credential compromise and lateral movement.
Mitigation strategies for CVE-2019-9623 should prioritize immediate patching of the Feng Office application to the latest secure version that addresses this specific vulnerability. Organizations must implement strict file type validation and sanitization for all uploaded files, particularly disabling the processing of .shtml files or any files containing server-side include directives. Network segmentation and web application firewalls should be configured to monitor and block suspicious file upload patterns. Input validation mechanisms should be enhanced to reject files containing embedded command execution directives, and the application should be configured to disable server-side include processing for uploaded content. Additionally, privileged access controls should be enforced to limit the execution privileges of the web server process, and regular security assessments should be conducted to identify similar vulnerabilities in other components of the application stack. The vulnerability highlights the importance of defense-in-depth strategies and proper input validation practices that align with secure coding guidelines outlined in OWASP Top Ten and NIST cybersecurity frameworks.