CVE-2017-8448 in X-Pack Alerting
Summary
by MITRE
An error was found in the permission model used by X-Pack Alerting 5.0.0 to 5.6.0 whereby users mapped to certain built-in roles could create a watch that results in that user gaining elevated privileges.
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Analysis
by VulDB Data Team • 11/20/2019
The vulnerability identified as CVE-2017-8448 represents a critical privilege escalation flaw within the X-Pack Alerting component of Elasticsearch versions 5.0.0 through 5.6.0. This issue stems from a fundamental weakness in the permission model implementation that allows authenticated users with specific built-in roles to exploit a design oversight in the watch creation process. The flaw specifically affects the security controls that govern how users interact with alerting mechanisms, creating an unintended pathway for privilege elevation that bypasses normal access control boundaries.
The technical root cause of this vulnerability lies in how X-Pack Alerting handles user permissions when processing watch definitions. When users with certain built-in roles create watches, the system fails to properly validate the privileges that the watch might grant to the executing user. This occurs because the permission model does not adequately distinguish between the privileges required for watch creation and the privileges that may be implicitly granted through watch execution. The flaw is particularly insidious because it operates at the intersection of role-based access control and watch execution contexts, allowing malicious actors to craft watches that, when executed, expand their own privileges within the system.
The operational impact of CVE-2017-8448 extends beyond simple privilege escalation to potentially enable broader system compromise. An attacker who can create watches with elevated privileges can effectively bypass the intended security boundaries of the Elasticsearch cluster, potentially gaining access to sensitive data, executing arbitrary commands, or establishing persistence mechanisms. This vulnerability particularly affects organizations that rely on X-Pack Alerting for monitoring and alerting while maintaining strict access controls, as it undermines the fundamental security assumptions that govern user access to cluster resources.
Organizations should immediately apply the security patches released by Elasticsearch to address this vulnerability, as the flaw has been classified under CWE-276, which represents improper privileges assignment in access control systems. The remediation process requires careful attention to the updated permission models and should be followed by comprehensive security audits to ensure no unauthorized watches have been created. Additionally, security teams should implement monitoring for watch creation activities and establish strict controls over which users can create watches, particularly those that might be used to escalate privileges. This vulnerability also aligns with ATT&CK technique T1078 which covers valid accounts and privilege escalation through legitimate system access, making it a significant concern for organizations following MITRE ATT&CK frameworks for threat modeling and defense.