CVE-2016-6797 in Tomcat
Summary
by MITRE
The ResourceLinkFactory implementation 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 and 6.0.0 to 6.0.45 did not limit web application access to global JNDI resources to those resources explicitly linked to the web application. Therefore, it was possible for a web application to access any global JNDI resource whether an explicit ResourceLink had been configured or not.
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Analysis
by VulDB Data Team • 09/29/2022
The vulnerability described in CVE-2016-6797 represents a critical access control flaw within Apache Tomcat's ResourceLinkFactory implementation across multiple versions including 9.0.0.M1 through 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. This issue fundamentally undermines the security boundaries that should exist between web applications and the underlying JNDI resource management system. The flaw stems from inadequate resource isolation mechanisms that fail to properly enforce access controls for global JNDI resources, creating a significant attack surface for malicious web applications.
The technical implementation flaw manifests in how Tomcat's ResourceLinkFactory handles JNDI resource access within web applications. Normally, web applications should only be able to access JNDI resources that have been explicitly configured and linked to them through proper ResourceLink declarations in the web application's deployment descriptor or context configuration. However, this vulnerability allows web applications to bypass these explicit access controls and directly access any global JNDI resource available within the server's JNDI namespace. This represents a direct violation of the principle of least privilege and demonstrates a failure in the container's resource management security model.
The operational impact of this vulnerability is severe and multifaceted, particularly when considering the widespread adoption of Apache Tomcat across enterprise environments. An attacker who can successfully exploit this vulnerability gains the ability to access sensitive global JNDI resources including database connections, LDAP directories, and other critical system resources that are typically intended to be isolated from web applications. This access could enable data exfiltration, privilege escalation, or further lateral movement within the network. The vulnerability is particularly dangerous because it affects multiple major versions of Tomcat, meaning that a vast number of applications and systems could be potentially compromised. According to CWE-284, this vulnerability maps directly to improper access control issues, specifically related to insufficient access control mechanisms in the JNDI resource management layer.
The security implications extend beyond simple unauthorized access, as this vulnerability can be leveraged for more sophisticated attacks within the context of the ATT&CK framework. Attackers can use this weakness to perform reconnaissance and enumeration of global resources, potentially discovering sensitive configurations or credentials stored in JNDI. The vulnerability could facilitate initial access and persistence mechanisms, particularly when combined with other exploitation techniques. Organizations running affected Tomcat versions face significant risk of data breaches, as web applications could access database connection pools, LDAP directories, or other critical system resources that should remain isolated from untrusted web content.
Mitigation strategies for CVE-2016-6797 should focus on immediate patching of affected Tomcat versions to the latest stable releases that contain the necessary security fixes. Organizations should also implement proper resource isolation practices, ensuring that web applications only have access to explicitly configured JNDI resources through proper ResourceLink declarations. Configuration hardening measures including the removal of unnecessary global JNDI resources, implementing strict access controls, and regularly auditing JNDI resource configurations can significantly reduce the attack surface. Additionally, organizations should consider implementing network segmentation and monitoring solutions to detect unauthorized access attempts to global JNDI resources, which aligns with ATT&CK techniques related to credential access and privilege escalation. Regular security assessments and vulnerability scanning should be conducted to identify any remaining instances of this vulnerability across the enterprise infrastructure.