CVE-2017-17727 in DeDeCMS
Summary
by MITRE
DedeCMS through 5.6 allows arbitrary file upload and PHP code execution by embedding the PHP code in a .jpg file, which is used in the templet parameter to member/article_edit.php.
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Analysis
by VulDB Data Team • 12/15/2019
The vulnerability CVE-2017-17727 represents a critical security flaw in DedeCMS versions up to 5.6 that enables remote attackers to achieve arbitrary file upload and subsequent PHP code execution. This vulnerability specifically targets the member/article_edit.php script and exploits a weakness in the handling of the templet parameter. The attack vector leverages the ability to embed malicious PHP code within image files, particularly jpg format, which are then processed through the vulnerable parameter. This type of vulnerability falls under CWE-434 which categorizes insecure file upload vulnerabilities where applications accept and process files without proper validation of their content or type. The flaw demonstrates a classic lack of input sanitization and improper file type validation that allows attackers to bypass security measures designed to prevent execution of malicious code.
The technical implementation of this vulnerability occurs when an attacker constructs a malicious jpg file containing embedded PHP code and uploads it through the member/article_edit.php endpoint. The system fails to properly validate the file type or content, allowing the jpg file to be treated as executable code rather than a simple image. This misconfiguration creates a path traversal and code execution vulnerability that can be exploited by remote unauthenticated users. The attack follows a common pattern seen in web application security flaws where file upload mechanisms lack proper content verification, allowing attackers to upload files with executable extensions or embedded code that gets executed by the web server. The vulnerability is particularly dangerous because it allows for full remote code execution without requiring authentication, making it an attractive target for attackers seeking to compromise web applications.
The operational impact of CVE-2017-17727 is severe and far-reaching for any organization using affected DedeCMS versions. Successful exploitation can lead to complete system compromise, allowing attackers to execute arbitrary commands, access sensitive data, install backdoors, and potentially use the compromised system as a pivot point for further attacks within the network. The vulnerability can be exploited through the standard web interface without requiring special privileges or advanced technical knowledge, making it accessible to a wide range of threat actors. From an attacker perspective, this vulnerability maps to several ATT&CK techniques including T1190 for Exploit Public-Facing Application and T1059 for Command and Scripting Interpreter, as it enables the execution of arbitrary code through web application exploitation. Organizations may face data breaches, system downtime, and potential regulatory compliance violations if this vulnerability is exploited.
Mitigation strategies for CVE-2017-17727 should focus on immediate patching of the affected DedeCMS versions to the latest secure releases that address the file upload validation issues. Organizations should implement strict file type validation and content checking mechanisms to prevent the upload of executable files regardless of their extension. The recommended approach includes implementing proper input sanitization, using whitelisting for allowed file types, and implementing Content Security Policy headers to prevent execution of embedded code. Additionally, organizations should consider implementing web application firewalls to detect and block suspicious upload patterns, and conduct regular security audits to identify similar vulnerabilities in other web applications. The remediation process should also include monitoring for any signs of exploitation attempts and ensuring that all file upload mechanisms in web applications properly validate file content and reject any files that contain executable code or suspicious embedded content. Security teams should also review and strengthen their overall application security posture to prevent similar vulnerabilities from occurring in other components of their web infrastructure.