CVE-2023-42819 in JumpServer
Summary
by MITRE • 09/27/2023
JumpServer is an open source bastion host. Logged-in users can access and modify the contents of any file on the system. A user can use the 'Job-Template' menu and create a playbook named 'test'. Get the playbook id from the detail page, like 'e0adabef-c38f-492d-bd92-832bacc3df5f'. An attacker can exploit the directory traversal flaw using the provided URL to access and retrieve the contents of the file. `https://jumpserver-ip/api/v1/ops/playbook/e0adabef-c38f-492d-bd92-832bacc3df5f/file/?key=../../../../../../../etc/passwd` a similar method to modify the file content is also present. This issue has been addressed in version 3.6.5. Users are advised to upgrade. There are no known workarounds for this vulnerability.
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Analysis
by VulDB Data Team • 10/16/2023
The vulnerability identified as CVE-2023-42819 affects JumpServer, an open source bastion host solution that provides secure access management for enterprise environments. This critical security flaw represents a directory traversal vulnerability that allows authenticated users to access and modify arbitrary files on the underlying system. The vulnerability exists within the playbook file handling functionality of the JumpServer application, specifically in the API endpoint responsible for managing playbook files. The issue manifests when users can leverage the Job-Template menu to create playbooks and subsequently exploit a path traversal flaw in the file retrieval mechanism.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization within the file path handling logic. When an attacker accesses the specific API endpoint with a crafted path traversal payload, the application fails to properly validate the requested file path, allowing access to sensitive system files such as /etc/passwd. The vulnerability specifically affects the URL structure where the key parameter accepts directory traversal sequences that bypass normal file access controls. This flaw operates at the application layer and demonstrates a classic path traversal vulnerability pattern that has been classified under CWE-22, which describes improper limitation of a pathname to a restricted directory.
The operational impact of this vulnerability is severe and far-reaching for organizations utilizing JumpServer as their primary bastion host solution. An authenticated attacker with access to the system can escalate their privileges beyond the intended scope of the application and gain read access to critical system files including password databases, configuration files, and potentially sensitive data stored on the server. The ability to modify file contents further amplifies the threat, as attackers could potentially inject malicious code or alter system configurations to maintain persistence. This vulnerability directly violates the principle of least privilege and undermines the core security objectives of a bastion host, which is designed to provide controlled access to target systems while maintaining strict isolation from the broader network infrastructure.
The attack vector is particularly concerning as it requires only authenticated access, meaning that any user with valid credentials to the JumpServer application can exploit this vulnerability. This makes the attack surface wider than initially apparent, as it does not require specialized privileges or complex exploitation techniques. The vulnerability affects the API endpoint that handles playbook file operations and can be exploited through simple URL manipulation. The specific implementation allows attackers to traverse directories using sequences like ../../../../../etc/passwd and retrieve or modify any file accessible to the application process. This issue has been remediated in version 3.6.5 of JumpServer, which implements proper input validation and path sanitization mechanisms. Organizations utilizing JumpServer should immediately upgrade to this patched version to mitigate the risk of exploitation, as no effective workarounds exist for this vulnerability. The remediation addresses the root cause by implementing proper validation of file paths and restricting access to system directories through proper access control mechanisms. This vulnerability aligns with ATT&CK technique T1059, which covers command and scripting interpreter, as it enables attackers to access system files that may contain credentials or configuration information that could be used for further exploitation. The impact of this vulnerability extends beyond simple file access, as it could enable attackers to compromise the integrity of the entire bastion host system and potentially gain access to all systems that the JumpServer manages access to.