CVE-2016-6794 in Tomcat
Summary
by MITRE
When a SecurityManager is configured, a web application's ability to read system properties should be controlled by the SecurityManager. In Apache Tomcat 9.0.0.M1 to 9.0.0.M9, 8.5.0 to 8.5.4, 8.0.0.RC1 to 8.0.36, 7.0.0 to 7.0.70, 6.0.0 to 6.0.45 the system property replacement feature for configuration files could be used by a malicious web application to bypass the SecurityManager and read system properties that should not be visible.
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Analysis
by VulDB Data Team • 09/29/2022
The vulnerability described in CVE-2016-6794 represents a critical security flaw in Apache Tomcat's handling of system property replacement within configuration files. This issue specifically affects versions ranging from 9.0.0.M1 through 9.0.0.M9, 8.5.0 through 8.5.4, 8.0.0.RC1 through 8.0.36, 7.0.0 through 7.0.70, and 6.0.0 through 6.0.45, creating a widespread impact across multiple major releases of the popular web application server. The vulnerability stems from the improper implementation of security controls that should normally be enforced by the Java SecurityManager, which is designed to restrict access to system resources and sensitive information.
The technical flaw manifests in the system property replacement feature that allows configuration files to contain placeholders that are automatically replaced with actual system property values during application startup. When a SecurityManager is properly configured, it should prevent unauthorized web applications from accessing system properties that contain sensitive information such as user directories, system paths, or environment variables. However, this vulnerability enables malicious web applications to circumvent these security restrictions by exploiting the property replacement mechanism, effectively allowing them to read system properties that should remain hidden from untrusted code. This bypass occurs because the system property replacement process does not properly validate or enforce the security context of the requesting application.
The operational impact of this vulnerability is severe and multifaceted, as it fundamentally undermines the security model of Apache Tomcat installations that rely on SecurityManager for access control. An attacker with access to deploy malicious web applications can exploit this vulnerability to gain unauthorized access to sensitive system information that could be used for further attacks, including privilege escalation, information gathering, or targeting other system components. The vulnerability particularly affects environments where Tomcat is used to host multiple applications with varying security requirements, as a compromised application could potentially access system properties belonging to other applications or the system itself. This issue directly violates the principle of least privilege and can lead to complete system compromise when combined with other vulnerabilities or attack vectors.
The vulnerability maps directly to CWE-284, which describes improper access control, and aligns with ATT&CK techniques such as T1068, which involves exploiting legitimate credentials and T1566, which covers spearphishing with a malicious attachment. Organizations should immediately apply the patched versions of Apache Tomcat to remediate this vulnerability, as there are no practical workarounds that maintain the security benefits of the SecurityManager. The recommended mitigation strategy involves upgrading to versions that contain the fix, typically Tomcat 9.0.0.M10, 8.5.5, 8.0.37, 7.0.71, or 6.0.46, respectively. Additionally, security administrators should conduct thorough audits of existing deployments to ensure no applications are running vulnerable versions and consider implementing additional monitoring for suspicious property access patterns. Organizations should also review their SecurityManager configurations to ensure they are properly implemented and tested, as this vulnerability demonstrates the critical importance of proper security boundary enforcement in application servers.