CVE-2018-14728 in Filemanager
Summary
by MITRE
upload.php in Responsive FileManager 9.13.1 allows SSRF via the url parameter.
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Analysis
by VulDB Data Team • 06/22/2024
The vulnerability identified as CVE-2018-14728 resides within the upload.php component of Responsive FileManager version 9.13.1, representing a server-side request forgery flaw that enables remote attackers to manipulate the application's file upload functionality. This issue manifests through the improper validation of the url parameter, which allows malicious actors to specify arbitrary URLs that the application will attempt to access and process during file upload operations. The vulnerability falls under the category of CWE-918, Server-Side Request Forgery, which is classified as a critical security weakness in web applications where user-controllable input is used to construct HTTP requests without adequate validation or sanitization. The flaw specifically enables attackers to bypass normal access controls and potentially gain unauthorized access to internal systems or services that would otherwise be protected by network segmentation.
The technical implementation of this vulnerability exploits the lack of proper input validation and sanitization within the file upload mechanism. When a user submits a file upload request through the upload.php script, the application accepts a url parameter that is intended to specify the source location of a file to be downloaded and uploaded. However, the application fails to validate or restrict the contents of this parameter, allowing attackers to provide malicious URLs that could point to internal network resources or external malicious servers. This creates a scenario where the application's own server makes outbound connections to attacker-controlled or internal targets, effectively enabling the attacker to perform reconnaissance or execute further attacks through the vulnerable application. The vulnerability is particularly concerning because it operates at the server level, meaning that successful exploitation could allow attackers to access internal network services that are not directly exposed to the internet.
The operational impact of this vulnerability extends beyond simple data exfiltration or unauthorized file uploads, as it can enable attackers to perform extensive reconnaissance of internal network infrastructure. An attacker could leverage this vulnerability to probe internal services, potentially discovering sensitive systems, databases, or network resources that are normally protected by firewalls or network segmentation. The vulnerability could also be combined with other attack vectors to escalate privileges or gain deeper access to the compromised system. According to ATT&CK framework, this vulnerability maps to T1071.004 Application Layer Protocol: DNS, as the SSRF attack may utilize DNS resolution to target internal resources, and T1566.001 Impair Defenses: Disable or Modify Tools, as it could be used to bypass security controls. The impact is particularly severe in environments where internal services are not properly isolated or where the vulnerable application has elevated privileges that could allow access to sensitive data or systems.
Mitigation strategies for CVE-2018-14728 should focus on implementing robust input validation and sanitization mechanisms within the application. Organizations should immediately patch the vulnerable version of Responsive FileManager to the latest available release that addresses this vulnerability. Additionally, network-level controls should be implemented to restrict outbound connections from the application server to prevent unauthorized access to internal resources. The implementation of a whitelist approach for allowed URLs, combined with proper input sanitization and validation, would effectively prevent exploitation of this vulnerability. Security monitoring should be enhanced to detect unusual outbound network requests from the application server, as these could indicate exploitation attempts. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation, ensuring that even if an attacker gains access through this vulnerability, they cannot easily move laterally within the network infrastructure. The vulnerability demonstrates the critical importance of validating all user inputs and implementing proper access controls to prevent attackers from leveraging application-level flaws to gain unauthorized access to internal systems.