CVE-2019-20390 in Subrion
Summary
by MITRE
A Cross-Site Request Forgery (CSRF) vulnerability was discovered in Subrion CMS 4.2.1 that allows a remote attacker to remove files on the server without a victim's knowledge, by enticing an authenticated user to visit an attacker's web page. The application fails to validate the CSRF token for a GET request. An attacker can craft a panel/uploads/read.json?cmd=rm URL (removing this token) and send it to the victim.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 05/16/2020
The CVE-2019-20390 vulnerability represents a critical cross-site request forgery flaw within Subrion CMS version 4.2.1 that demonstrates a fundamental failure in web application security controls. This vulnerability operates through a sophisticated attack vector that exploits the trust relationship between the web application and its authenticated users, creating a dangerous scenario where malicious actors can execute unauthorized operations on behalf of legitimate users. The flaw specifically targets the application's insufficient validation of cross-site request forgery tokens for GET requests, which violates established security principles and undermines the integrity of the application's authentication mechanisms.
The technical implementation of this vulnerability stems from the application's improper handling of stateful operations within the GET request method, which should typically be idempotent and safe for use in cross-site contexts. The flaw manifests when the application fails to require or validate CSRF tokens for file removal operations, particularly in the panel/uploads/read.json endpoint that processes commands through the cmd=rm parameter. This design oversight allows attackers to construct malicious URLs that automatically execute file deletion operations without requiring user interaction beyond visiting a compromised page. The vulnerability is particularly dangerous because it leverages the authenticated session of a legitimate user to perform administrative operations, bypassing normal access controls and authorization checks that should prevent such actions.
The operational impact of this vulnerability extends far beyond simple data loss, as it enables attackers to completely compromise the integrity and availability of the web application's file system. An attacker can systematically remove critical application files, configuration data, or user content, potentially leading to complete application failure or data destruction. The attack requires minimal technical expertise and can be executed through simple web page embedding, making it particularly dangerous for widespread exploitation. The vulnerability creates a persistent threat vector where even a single compromised user account can provide attackers with the ability to damage or destroy the entire content management system infrastructure. This type of vulnerability directly maps to CWE-352, which specifically addresses Cross-Site Request Forgery weaknesses in web applications.
Mitigation strategies for this vulnerability must address both the immediate security gap and prevent similar issues in future implementations. The primary remediation involves implementing proper CSRF token validation for all state-changing operations, regardless of HTTP method, and ensuring that GET requests are not used for destructive operations when authentication is required. Organizations should implement robust token generation and validation mechanisms that are tied to user sessions and include proper expiration controls. The solution aligns with ATT&CK technique T1078 which covers legitimate credentials and T1566 which addresses credential harvesting through social engineering. Additionally, implementing Content Security Policy headers and proper input validation can help reduce the attack surface and prevent successful exploitation of similar CSRF vulnerabilities. Regular security assessments and code reviews focusing on authentication and authorization controls are essential for preventing such issues from reoccurring in the application's architecture.