CVE-2019-0233 in Struts
Summary
by MITRE
An access permission override in Apache Struts 2.0.0 to 2.5.20 may cause a Denial of Service when performing a file upload.
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Analysis
by VulDB Data Team • 09/14/2020
The vulnerability identified as CVE-2019-0233 represents a critical access permission override flaw within Apache Struts 2 framework versions ranging from 2.0.0 through 2.5.20. This issue specifically manifests during file upload operations and can be exploited to trigger a Denial of Service condition that severely impacts system availability. The vulnerability stems from insufficient validation of file upload permissions within the framework's core processing mechanisms, creating a pathway for unauthorized access control bypass.
The technical implementation of this vulnerability resides in the file upload handling component of Apache Struts 2 where the system fails to properly validate user permissions before allowing file upload operations to proceed. When a user attempts to upload a file through the framework, the system should verify that the user possesses appropriate authorization levels to perform such operations. However, due to the permission override flaw, the system accepts upload requests regardless of the user's actual authorization status, potentially allowing malicious actors to upload files to restricted directories or overwrite existing critical files.
From an operational perspective, this vulnerability creates significant risk for organizations utilizing affected Apache Struts versions as it can be leveraged to disrupt service availability through multiple attack vectors. An attacker could potentially upload malicious files that consume system resources or exploit the permission bypass to gain unauthorized access to restricted directories. The Denial of Service impact extends beyond simple service disruption to include potential data integrity compromise and unauthorized system access, particularly when combined with other vulnerabilities within the same framework.
The vulnerability aligns with CWE-284, which addresses improper access control issues, and demonstrates how insufficient permission validation can lead to system compromise. From an ATT&CK framework perspective, this vulnerability maps to T1059.007 for command and scripting interpreter and T1499.004 for network denial of service, as attackers can leverage the permission override to execute malicious commands or disrupt network services through file upload operations. Organizations should immediately implement mitigations including upgrading to Apache Struts 2.5.21 or later versions, implementing proper input validation, and establishing robust file upload permission controls to prevent exploitation of this vulnerability.
Mitigation strategies should encompass both immediate remediation actions and long-term architectural improvements. The primary recommendation involves upgrading to Apache Struts 2.5.21 or higher versions where this vulnerability has been addressed through enhanced permission validation mechanisms. Additionally, organizations should implement comprehensive file upload restrictions including directory permissions, file type validation, and size limitations to prevent unauthorized file operations. Network segmentation and firewall rules can further limit access to upload endpoints, while regular security assessments should verify that all file upload operations properly enforce authorization controls. The vulnerability serves as a critical reminder of the importance of proper access control implementation in web application frameworks and the necessity of maintaining current security patches to prevent exploitation of known vulnerabilities.