CVE-2017-7570 in PivotX
Summary
by MITRE
PivotX 2.3.11 allows remote authenticated Advanced users to execute arbitrary PHP code by performing an upload with a safe file extension (such as .jpg) and then invoking the duplicate function to change to the .php extension.
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Analysis
by VulDB Data Team • 09/28/2020
The vulnerability identified as CVE-2017-7570 affects PivotX 2.3.11, a content management system that permits authenticated users with advanced privileges to execute arbitrary PHP code through a specific file upload manipulation technique. This represents a critical security flaw that undermines the application's file validation mechanisms and could lead to complete system compromise. The vulnerability operates through a two-step process that exploits the application's handling of file extensions and duplicate functions, creating a path for malicious code execution that bypasses normal security controls.
The technical implementation of this vulnerability involves a sophisticated attack vector that leverages the application's file upload functionality combined with its duplicate handling mechanism. An authenticated advanced user can upload a file with a seemingly benign extension such as .jpg or .png, which passes the initial security checks due to the application's permissive file type validation. Once the file is uploaded, the attacker can invoke the duplicate function to rename the file extension from .jpg to .php, effectively transforming a legitimate media file into an executable PHP script. This technique exploits a fundamental flaw in the application's file extension handling logic and demonstrates poor input validation practices that allow attackers to manipulate file types after initial upload.
The operational impact of this vulnerability extends far beyond simple code execution, as it provides attackers with the ability to gain full control over the affected system. Once the malicious PHP code is executed, attackers can perform a wide range of malicious activities including data exfiltration, privilege escalation, backdoor installation, and further network reconnaissance. The vulnerability affects the application's core security model by allowing authenticated users to escalate their privileges and bypass security controls that should normally prevent code execution. This type of vulnerability is particularly dangerous in web applications where file upload functionalities are commonly used and where proper validation mechanisms are essential for maintaining system integrity.
From a cybersecurity perspective, this vulnerability aligns with CWE-434, which describes the weakness of unrestricted file upload, and demonstrates characteristics consistent with ATT&CK technique T1059.007 for command and scripting interpreter. The attack pattern follows a common exploitation methodology where an attacker first gains access through legitimate user privileges and then leverages application flaws to achieve code execution. Organizations should consider this vulnerability as part of a broader attack surface that includes file upload handlers, privilege escalation mechanisms, and input validation controls. The vulnerability also reflects poor security architecture decisions that fail to implement proper file type validation, extension checking, and upload directory restrictions that are fundamental requirements for secure file handling in web applications.
The mitigation strategies for this vulnerability require immediate implementation of multiple security controls to prevent exploitation. Organizations should implement strict file type validation that checks both MIME types and file extensions against whitelisted safe formats, disable execution permissions on upload directories, and implement proper file naming conventions that prevent extension manipulation. Additionally, the application should enforce proper access controls and audit all file upload activities to detect suspicious behavior patterns. Regular security updates and patches should be applied to address known vulnerabilities, and comprehensive security testing should be performed to identify similar flaws in other application components. The vulnerability also underscores the importance of principle of least privilege implementation and proper user access control mechanisms that prevent advanced users from performing operations that could compromise system security.