CVE-2017-14146 in HelpDEZk
Summary
by MITRE
HelpDEZk 1.1.1 allows remote authenticated users to execute arbitrary PHP code by uploading a .php attachment and then requesting it in the helpdezk\app\uploads\helpdezk\attachments\ directory.
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Analysis
by VulDB Data Team • 11/13/2019
The vulnerability identified as CVE-2017-14146 represents a critical remote code execution flaw in HelpDEZk version 1.1.1 that demonstrates a classic insecure file upload vulnerability pattern. This issue arises from inadequate input validation and sanitization mechanisms within the application's file handling processes, allowing authenticated users to bypass security controls and upload malicious PHP files to the server. The vulnerability specifically targets the helpdezkppuploads helpdezkppattachments directory, which serves as the default storage location for user-uploaded files. This flaw exemplifies CWE-434 which categorizes insecure file upload vulnerabilities where applications fail to properly validate file types and contents before storing them on the server. The attack vector is particularly dangerous because it requires only authenticated access, meaning that any user with valid credentials can exploit this weakness to gain arbitrary code execution privileges on the affected system.
The technical exploitation of this vulnerability involves a two-step process that begins with the authenticated user uploading a malicious PHP file through the application's attachment functionality. Once the file is successfully uploaded to the designated directory, the attacker can then request the file directly through the web server, causing the PHP code to execute within the context of the web application's privileges. This creates a persistent backdoor or attack surface that can be leveraged for various malicious activities including data exfiltration, system compromise, or further network reconnaissance. The vulnerability essentially creates a server-side code execution environment where the uploaded PHP payload can interact with the underlying operating system and database resources. This type of vulnerability directly aligns with ATT&CK technique T1059.007 which describes the execution of code through web shells and file upload mechanisms, and demonstrates the principle of privilege escalation through authenticated access points.
The operational impact of CVE-2017-14146 extends beyond immediate code execution capabilities to encompass broader system compromise and data integrity threats. Successful exploitation can lead to complete system takeover where attackers gain full administrative privileges, potentially resulting in unauthorized access to sensitive customer data, financial records, or proprietary business information. The vulnerability also enables attackers to establish persistent access through the uploaded PHP files, allowing them to maintain control over the system even after initial exploitation. Organizations using HelpDEZk 1.1.1 face significant risk of data breaches, service disruption, and compliance violations, particularly in regulated environments where such vulnerabilities can result in substantial financial penalties and reputational damage. The attack scenario represents a common pattern in web application exploitation where initial authenticated access is leveraged to achieve remote code execution, making this vulnerability particularly concerning for organizations that rely on help desk systems for customer support and internal communications.
Mitigation strategies for CVE-2017-14146 should focus on implementing robust file validation controls and restricting file upload capabilities within the application. Organizations must enforce strict file type validation by checking file extensions against a whitelist of allowed formats and implementing proper content validation to prevent PHP files from being executed. The recommended approach includes configuring the web server to prevent execution of PHP files within upload directories, implementing proper access controls, and ensuring that uploaded files are stored outside the web root directory. Additionally, organizations should implement proper input sanitization, validate file contents using multiple verification methods, and consider implementing file name randomization to prevent predictable file paths. Security hardening measures such as disabling unnecessary file upload features, implementing rate limiting for upload operations, and monitoring upload activities through logging and alerting systems should be deployed. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in the application's file handling processes, while immediate patching or upgrading to a fixed version of HelpDEZk is essential to prevent exploitation of this vulnerability. The remediation process should also include comprehensive security training for developers to prevent similar issues in future application development cycles and ensure adherence to secure coding practices that prevent insecure file upload vulnerabilities.