CVE-2015-5074 in X2CRM
Summary
by MITRE
Incomplete blacklist vulnerability in the FileUploadsFilter class in protected/components/filters/FileUploadsFilter.php in X2Engine X2CRM before 5.0.9 allows remote authenticated users to execute arbitrary PHP code by uploading a file with a .pht extension.
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Analysis
by VulDB Data Team • 11/24/2024
The vulnerability identified as CVE-2015-5074 represents a critical security flaw in X2Engine X2CRM versions prior to 5.0.9, specifically within the FileUploadsFilter class located in protected/components/filters/FileUploadsFilter.php. This issue constitutes an incomplete blacklist vulnerability that fundamentally undermines the application's file upload security controls. The flaw allows authenticated attackers to bypass security restrictions by exploiting a weakness in the file extension validation mechanism, creating a pathway for arbitrary code execution through carefully crafted file uploads.
The technical implementation of this vulnerability stems from the inadequate filtering of file extensions within the FileUploadsFilter component. When users upload files through the application's interface, the system should validate file types against a comprehensive whitelist or a properly maintained blacklist to prevent execution of malicious code. However, the vulnerability demonstrates that the system fails to adequately block files with the .pht extension, which is a PHP include file extension that can be executed by the web server. This particular extension bypasses the existing security controls, enabling attackers to upload PHP code that will be executed in the context of the web server, thereby compromising the entire application environment.
From an operational perspective, this vulnerability has severe implications for organizations using affected versions of X2Engine X2CRM. The fact that the attack requires only authenticated access significantly reduces the attack surface compared to unauthenticated exploits, making it particularly dangerous in environments where legitimate users have access to the system. Attackers who can authenticate to the application can upload malicious PHP files with .pht extensions that will be executed server-side, potentially leading to complete system compromise, data exfiltration, and persistence mechanisms. The impact extends beyond immediate code execution to include potential privilege escalation and lateral movement within the network infrastructure.
The vulnerability aligns with CWE-434, which describes the weakness of allowing untrusted data to be uploaded to a web server, and demonstrates characteristics of CWE-20, which covers input validation issues in software. From an ATT&CK framework perspective, this vulnerability maps to T1078 for valid accounts and T1190 for exploitation of remote services, while also supporting T1059 for command and scripting interpreter execution. The attack chain typically involves initial authentication, file upload with malicious .pht extension, and subsequent code execution, making it a prime candidate for exploitation in advanced persistent threat scenarios. Organizations should prioritize immediate patching to version 5.0.9 or later, implement additional upload validation controls, and conduct comprehensive security assessments to identify potential exploitation attempts in their environments.
This vulnerability highlights the critical importance of robust input validation and the dangers of incomplete security measures in web applications. The use of a simple blacklist approach without proper validation mechanisms creates a false sense of security that attackers can exploit to gain unauthorized access and execute arbitrary code. The security implications extend beyond the immediate application to include potential data breaches, service disruption, and regulatory compliance violations that organizations must address through immediate remediation and enhanced security monitoring procedures.