CVE-2016-7452 in Exponent
Summary
by MITRE
The Pixidou Image Editor in Exponent CMS prior to v2.3.9 patch 2 could be used to upload a malicious file to any folder on the site via a cpi directory traversal.
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Analysis
by VulDB Data Team • 09/29/2022
The vulnerability identified as CVE-2016-7452 represents a critical directory traversal flaw within the Pixidou Image Editor component of Exponent CMS versions prior to v2.3.9 patch 2. This issue stems from inadequate input validation and improper file handling mechanisms that allow attackers to manipulate the upload process and place malicious files in arbitrary directories throughout the web application's file system. The vulnerability specifically affects the cpi parameter which controls the target directory for file uploads, creating a path traversal condition that bypasses normal security restrictions. This flaw falls under the CWE-22 category of Path Traversal attacks, where improper input validation allows attackers to access files and directories outside the intended scope of the application.
The technical exploitation of this vulnerability involves crafting a malicious upload request that includes directory traversal sequences such as ../ or ..\ in the cpi parameter value. When the application processes this parameter without proper sanitization, it interprets the traversal sequences and places the uploaded file in a location specified by the attacker rather than the intended directory. This creates a significant security risk as attackers can potentially upload web shells, malicious scripts, or other harmful files to critical system directories, bypassing normal access controls and file permission mechanisms that would typically prevent such unauthorized placements. The vulnerability essentially grants remote attackers the ability to execute arbitrary code on the target system through the upload functionality, as demonstrated by the potential for web shell deployment.
The operational impact of CVE-2016-7452 extends far beyond simple unauthorized file placement, as it provides attackers with a potential foothold for further system compromise and persistent access. Once an attacker successfully exploits this vulnerability, they can establish backdoors, escalate privileges, and potentially move laterally within the network infrastructure. The affected Exponent CMS installations become vulnerable to full system compromise, with attackers able to manipulate the web application's behavior, steal sensitive data, or use the compromised system as a launching point for attacks on other systems. This vulnerability directly aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1078.004 for Valid Accounts, as it enables attackers to execute malicious code and potentially maintain persistence through uploaded web shells or scripts that can be accessed through the compromised web server.
Organizations affected by this vulnerability should immediately implement multiple layers of mitigation strategies to protect their systems. The primary remediation involves updating Exponent CMS to version v2.3.9 patch 2 or later, which includes proper input validation and sanitization for the cpi parameter. Additionally, administrators should implement strict file type validation and content inspection mechanisms to prevent execution of malicious files even if directory traversal attempts are partially successful. Network-level protections such as web application firewalls should be configured to monitor and block suspicious upload requests containing directory traversal sequences. Access controls should be reinforced through proper file permissions and directory structure management to limit the damage potential even if exploitation occurs. The vulnerability demonstrates the critical importance of input validation and proper security coding practices as outlined in OWASP Top 10 and ISO 27001 security standards, emphasizing that all user-supplied data must be properly validated and sanitized before processing to prevent path traversal and similar injection attacks.