CVE-2018-19127 in PHPCMS 2008
Summary
by MITRE
A code injection vulnerability in /type.php in PHPCMS 2008 allows attackers to write arbitrary content to a website cache file with a controllable filename, leading to arbitrary code execution. The PHP code is sent via the template parameter, and is written to a data/cache_template/*.tpl.php file along with a "<?php function " substring.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 04/11/2020
The vulnerability CVE-2018-19127 represents a critical code injection flaw in PHPCMS 2008's type.php component that fundamentally undermines the application's security posture. This issue resides within the template handling mechanism where user-controllable input is improperly sanitized before being written to cache files, creating an avenue for remote attackers to execute arbitrary code on the target system. The vulnerability specifically targets the data/cache_template directory structure where template files are stored, making it particularly dangerous as it allows attackers to manipulate the caching infrastructure that powers the website's dynamic content generation.
The technical exploitation mechanism relies on the template parameter being directly processed and written to .tpl.php cache files without adequate input validation or sanitization. When attackers submit malicious PHP code through the template parameter, this code gets concatenated with a "<?php function " substring and subsequently written to cache files in the data/cache_template directory. This process creates a persistent backdoor within the application's caching layer, as the malicious code becomes part of the legitimate cache files that are subsequently executed during normal website operations. The vulnerability demonstrates a classic path traversal and code injection pattern that aligns with CWE-94, which specifically addresses the improper execution of code in interpreted languages.
The operational impact of this vulnerability extends far beyond simple code execution, as it provides attackers with complete control over the affected web server. Once exploited, attackers can execute arbitrary commands with the privileges of the web server process, potentially leading to data exfiltration, system compromise, or further lateral movement within the network. The cache-based persistence mechanism makes this vulnerability particularly insidious because the malicious code remains active even after the initial exploit, continuously executing whenever the cached template files are accessed. This characteristic places the vulnerability in the ATT&CK matrix under the T1059.007 technique for 'Command and Scripting Interpreter: PowerShell' and T1078.004 for 'Valid Accounts: Cloud Accounts' when considering the broader attack surface and potential for credential theft.
Mitigation strategies must address both the immediate vulnerability and the underlying architectural issues that enabled it. Organizations should implement strict input validation and sanitization for all user-supplied data, particularly within template handling components, ensuring that no executable code can be written to cache files. The application should enforce proper file permissions and directory restrictions to prevent unauthorized write access to cache directories, while also implementing secure coding practices that eliminate the possibility of direct code injection into cached template files. Additionally, regular security audits should verify that all temporary and cache directories are properly secured and that no arbitrary file write operations can occur without proper authentication and authorization checks. The vulnerability highlights the importance of principle of least privilege implementation and proper output encoding when handling dynamic content generation in web applications.