CVE-2018-13790 in concrete5
Summary
by MITRE
A Server Side Request Forgery (SSRF) vulnerability in tools/files/importers/remote.php in concrete5 8.2.0 can lead to attacks on the local network and mapping of the internal network, because of URL functionality on the File Manager page.
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Analysis
by VulDB Data Team • 03/03/2020
The CVE-2018-13790 vulnerability represents a critical server-side request forgery flaw discovered in concrete5 version 8.2.0 within the remote.php file located in the tools/files/importers/ directory. This vulnerability specifically affects the File Manager page functionality and exposes the application to significant security risks through improper input validation and URL handling mechanisms. The flaw allows malicious actors to manipulate the application's file import functionality to make unauthorized requests to internal network resources, effectively bypassing normal network security controls. The vulnerability stems from the application's failure to properly validate and sanitize user-supplied URLs, creating an attack surface that can be exploited to perform reconnaissance and potentially execute further malicious activities against internal systems.
The technical implementation of this vulnerability occurs when the concrete5 application processes file imports from remote sources through the File Manager interface. The remote.php script accepts URL parameters without adequate validation, allowing attackers to specify arbitrary URLs that the server will attempt to access on behalf of the application. This creates a dangerous scenario where legitimate server processes can be coerced into making HTTP requests to internal network addresses, effectively enabling attackers to probe internal systems, map network topology, and potentially access sensitive internal resources. The vulnerability is particularly concerning because it operates at the server level, meaning that successful exploitation can provide attackers with information about internal network structure and potentially lead to further compromise of internal systems. This type of vulnerability is classified under CWE-918 as Server-Side Request Forgery, which specifically addresses the risk of servers being tricked into making unauthorized requests to internal or external resources.
The operational impact of this vulnerability extends beyond simple network reconnaissance to potentially enable more sophisticated attacks within the target environment. Attackers can leverage the SSRF vulnerability to map internal network services, identify running applications, and potentially exploit other vulnerabilities they discover during the reconnaissance phase. The ability to make requests from the server's perspective means that attackers can bypass client-side firewalls and network security controls that would normally protect internal systems. This vulnerability also provides a potential pathway for attackers to access internal services that are not directly exposed to the internet, effectively extending their attack surface. The impact is particularly severe in environments where concrete5 is used as a content management system for internal applications or where the application has elevated privileges on the network. Organizations using concrete5 8.2.0 may find their internal networks exposed to reconnaissance activities that could lead to more serious security incidents.
Mitigation strategies for CVE-2018-13790 should focus on immediate patching of the concrete5 application to version 8.2.1 or later, which contains the necessary fixes for this vulnerability. Organizations should also implement network-level restrictions to prevent the application server from accessing internal network resources, particularly by implementing firewall rules that block outbound connections to internal IP ranges from the web server. Input validation should be strengthened to ensure that all URL parameters are properly sanitized and validated before processing, with additional restrictions on protocol schemes and destination addresses. The principle of least privilege should be applied to the application's network access, limiting its ability to make outbound requests to internal resources. Security monitoring should be enhanced to detect unusual outbound network requests from the application server, which could indicate exploitation attempts. Additionally, organizations should consider implementing web application firewalls to provide additional protection against similar SSRF vulnerabilities and should conduct regular security assessments to identify other potential attack vectors within their concrete5 installations. This vulnerability aligns with ATT&CK technique T1018 for Valid Accounts and T1046 for Network Service Scanning, demonstrating how SSRF can be used as a reconnaissance tool in broader attack campaigns.