CVE-2018-19692 in tp5cms
Summary
by MITRE
An issue was discovered in tp5cms through 2017-05-25. admin.php/upload/picture.html allows remote attackers to execute arbitrary PHP code by uploading a .php file with the image/jpeg content type.
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Analysis
by VulDB Data Team • 04/16/2020
The vulnerability identified as CVE-2018-19692 represents a critical security flaw in tp5cms version 2017-05-25 and earlier, where the administrative upload functionality fails to properly validate file types and content. This weakness creates a pathway for remote attackers to execute arbitrary PHP code through a carefully crafted file upload attack. The vulnerability specifically targets the admin.php/upload/picture.html endpoint, which is designed to handle image uploads but lacks adequate validation mechanisms to prevent the upload of malicious PHP files disguised as image content.
The technical implementation of this vulnerability stems from insufficient input validation and content type verification within the file upload handler. Attackers can exploit this by creating a PHP file with malicious code and then renaming it to have a .php extension while simultaneously setting the HTTP content type header to image/jpeg. The application's failure to perform comprehensive file validation allows the system to accept and process the malicious file as if it were a legitimate image, leading to arbitrary code execution on the server. This type of vulnerability falls under CWE-434 which specifically addresses the insecure upload of files with dangerous types, and represents a classic case of insufficient validation on file uploads.
The operational impact of this vulnerability is severe and far-reaching for any organization using affected versions of tp5cms. Remote code execution capabilities provide attackers with full control over the affected web server, enabling them to access sensitive data, modify website content, establish backdoors, and potentially use the compromised system as a launch point for further attacks within the network. The vulnerability's remote exploitability means that attackers do not require physical access or local credentials to compromise the system, making it particularly dangerous in environments where the application is publicly accessible. According to ATT&CK framework, this vulnerability maps to T1059.007 for command and script interpreter and T1566 for malicious file execution, representing the attack vectors that adversaries would use to leverage such a weakness.
Mitigation strategies for CVE-2018-19692 must focus on implementing comprehensive file validation and sanitization measures. Organizations should immediately upgrade to a patched version of tp5cms that addresses this vulnerability, as the vendor has released updates containing proper file type validation. Additional defensive measures include implementing strict file extension filtering, validating file content using multiple methods such as MIME type detection and file signature verification, and ensuring that uploaded files are stored in non-executable directories. Network segmentation and web application firewalls can provide additional layers of protection, while regular security audits and penetration testing should be conducted to identify and remediate similar vulnerabilities. The implementation of proper access controls and monitoring of upload activities can help detect and prevent exploitation attempts. Organizations should also consider implementing the principle of least privilege for file upload handlers and ensure that uploaded files are scanned for malicious content before being made available to users.