CVE-2016-7790 in Exponent
Summary
by MITRE
Exponent CMS 2.3.9 suffers from a remote code execution vulnerability in /install/index.php. An attacker can upload 'php' file to the website through uploader_paste.php, then overwrite /framework/conf/config.php, which leads to arbitrary code execution.
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Analysis
by VulDB Data Team • 07/20/2020
The vulnerability identified as CVE-2016-7790 represents a critical remote code execution flaw within Exponent CMS version 2.3.9 that stems from inadequate input validation and file handling mechanisms. This vulnerability exists in the installation component of the content management system, specifically within the /install/index.php file which provides an upload interface for system configuration. The flaw allows malicious actors to escalate their privileges from simple file upload to full system compromise through a carefully crafted attack chain.
The technical exploitation of this vulnerability begins with the attacker leveraging the uploader_paste.php component which accepts file uploads without proper validation. This component permits the upload of php files to the web server, bypassing normal security restrictions that should prevent execution of php code in upload directories. The vulnerability is further amplified by the ability to overwrite the critical configuration file /framework/conf/config.php which contains system-level settings and potentially sensitive information. This configuration file overwrite capability creates a persistent backdoor that allows attackers to execute arbitrary code with the privileges of the web server process.
The operational impact of CVE-2016-7790 extends far beyond simple unauthorized access, as it provides attackers with complete control over the affected web server. Once exploited, adversaries can establish persistent access, exfiltrate sensitive data, modify website content, and use the compromised system as a launchpad for further attacks within the network. The vulnerability's remote nature means attackers can exploit it from anywhere on the internet without requiring physical access or prior authentication. This makes it particularly dangerous for organizations that do not maintain proper network segmentation or monitoring controls around their web applications.
This vulnerability maps directly to CWE-434 which describes insecure file upload vulnerabilities where applications accept files from untrusted sources without proper validation. The attack pattern aligns with ATT&CK technique T1190 which covers exploiting vulnerabilities in web applications to gain remote code execution. Additionally, the privilege escalation aspect of overwriting configuration files relates to ATT&CK technique T1068 which involves exploiting vulnerabilities to gain elevated privileges. Organizations should implement strict file type validation, restrict upload directories from executing code, and ensure proper access controls on configuration files to prevent this type of exploitation. The vulnerability also highlights the importance of keeping CMS installations updated and following secure coding practices that prevent dangerous file operations in web applications.