CVE-2018-12538 in Jetty
Summary
by MITRE
In Eclipse Jetty versions 9.4.0 through 9.4.8, when using the optional Jetty provided FileSessionDataStore for persistent storage of HttpSession details, it is possible for a malicious user to access/hijack other HttpSessions and even delete unmatched HttpSessions present in the FileSystem's storage for the FileSessionDataStore.
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Analysis
by VulDB Data Team • 03/28/2023
The vulnerability identified as CVE-2018-12538 affects Eclipse Jetty web server versions 9.4.0 through 9.4.8, specifically when utilizing the FileSessionDataStore component for session persistence. This flaw represents a critical security weakness in web application session management that can lead to unauthorized access and session hijacking. The FileSessionDataStore component is designed to store HTTP session data on the filesystem for persistent sessions across server restarts, but this implementation contains a fundamental security flaw that allows malicious actors to manipulate session storage directories. The vulnerability stems from insufficient access controls and improper session isolation mechanisms within the filesystem-based session storage implementation, creating a path for unauthorized users to traverse session directories and access data belonging to other users. This issue directly impacts the confidentiality and integrity of web applications relying on Jetty's session persistence features, particularly those handling sensitive user information or requiring strict session isolation.
The technical root cause of this vulnerability lies in the improper handling of filesystem paths and session directory permissions within the FileSessionDataStore implementation. When multiple sessions are stored in the same filesystem directory, the vulnerability allows attackers to enumerate session identifiers and access session files belonging to other users. The flaw operates through directory traversal techniques that exploit weak input validation and insufficient permission checks when accessing session storage locations. Attackers can leverage this weakness to not only read session data but also modify or delete session files, effectively enabling session hijacking and potential account takeover scenarios. The vulnerability is classified under CWE-22 as "Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')" and aligns with ATT&CK technique T1563.002 for "Impairing Defenses: Disable or Modify Tools" and T1190 for "Exploit Public-Facing Application" in its exploitation methods. The implementation fails to properly validate session identifiers against the expected storage directory structure, allowing arbitrary filesystem access patterns that bypass intended security boundaries.
The operational impact of CVE-2018-12538 extends beyond simple session theft to encompass potential data corruption and service disruption within affected web applications. Malicious users can exploit this vulnerability to delete legitimate session files, causing session invalidation for unsuspecting users and potentially leading to denial of service conditions. The ability to access other users' session data creates opportunities for privilege escalation attacks, especially in applications where session data contains sensitive authentication tokens or authorization information. Web applications using Jetty's FileSessionDataStore are particularly vulnerable when deployed in multi-user environments or when session data contains session-specific permissions or roles. This vulnerability affects the fundamental security model of session management in web applications and can lead to cascading security issues if exploited in conjunction with other vulnerabilities. The impact is amplified in environments where session data is not properly encrypted at rest, making the vulnerability particularly dangerous for applications handling personal identifiable information or financial data.
Organizations affected by this vulnerability should prioritize immediate remediation through upgrading to Jetty version 9.4.9 or later, which contains the necessary fixes for the FileSessionDataStore session management flaw. The recommended mitigation strategy includes implementing proper access controls on session storage directories, ensuring that session files are stored with appropriate permissions and that the filesystem access patterns are properly validated. Network segmentation and monitoring of session storage directory access patterns can provide additional detection capabilities for potential exploitation attempts. Security teams should also consider implementing session encryption and alternative session storage mechanisms such as database-backed session stores that provide better isolation guarantees. The vulnerability demonstrates the importance of proper input validation and access control implementation in web server components, particularly those handling user session data. Organizations should conduct comprehensive security assessments of their web application environments to identify any other instances of similar vulnerabilities and ensure that all session management components are properly configured and secured. This vulnerability serves as a reminder of the critical importance of secure session management practices in web applications and the need for regular security updates to address known vulnerabilities in server components.