CVE-2018-15495 in Filemanager
Summary
by MITRE
/filemanager/upload.php in Responsive FileManager before 9.13.3 allows Directory Traversal and SSRF because the url parameter is used directly in a curl_exec call, as demonstrated by a file:///etc/passwd value.
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Analysis
by VulDB Data Team • 03/16/2020
The vulnerability identified as CVE-2018-15495 resides within the Responsive FileManager application, specifically in the filemanager/upload.php component. This issue affects versions prior to 9.13.3 and represents a critical security flaw that combines elements of directory traversal and server-side request forgery. The vulnerability stems from improper input validation and sanitization of the url parameter, which is directly utilized in a curl_exec function call without adequate security measures. This design flaw creates a pathway for attackers to manipulate the application's behavior and potentially access sensitive system resources.
The technical implementation of this vulnerability occurs when an attacker provides a malicious url parameter value such as file:///etc/passwd to the upload.php script. The application processes this input directly without validation, allowing the curl_exec function to execute with the crafted URL. This enables attackers to perform directory traversal attacks by accessing local files on the server through the file:// protocol, while simultaneously enabling server-side request forgery that can target internal network resources. The vulnerability operates at the intersection of CWE-22 Directory Traversal and CWE-918 Server-Side Request Forgery, creating a compound security risk that significantly amplifies the potential impact.
The operational impact of this vulnerability extends beyond simple file access, as it can enable attackers to extract sensitive system information including user credentials, configuration files, and other critical data stored on the server. The SSRF component allows attackers to potentially access internal services that should remain isolated from external networks, while the directory traversal aspect provides unauthorized access to local files that may contain authentication tokens, database connection details, or other confidential information. This vulnerability can be exploited remotely without requiring authentication, making it particularly dangerous for web applications that handle sensitive data or operate in environments with restricted network access.
Organizations affected by this vulnerability should immediately implement mitigations including input validation and sanitization of all user-supplied parameters, particularly those used in HTTP request operations. The recommended approach involves implementing strict parameter validation that rejects or filters out potentially dangerous protocols such as file://, ftp://, and other schemes that could enable unauthorized file access or network requests. Additionally, implementing proper access controls and network segmentation can help limit the potential damage from such exploits. Security professionals should also consider implementing web application firewalls that can detect and block suspicious parameter values, and conduct thorough security testing to identify similar vulnerabilities in other components of the application stack. The ATT&CK framework categorizes this as a technique involving Server-Side Request Forgery and Directory Traversal, emphasizing the need for comprehensive defensive measures that address both the immediate exploitation vector and broader application security posture.