CVE-2018-7206 in JupyterHub OAuthenticator
Summary
by MITRE
An issue was discovered in Project Jupyter JupyterHub OAuthenticator 0.6.x before 0.6.2 and 0.7.x before 0.7.3. When using JupyterHub with GitLab group whitelisting for access control, group membership was not checked correctly, allowing members not in the whitelisted groups to create accounts on the Hub. (Users were not allowed to access other users' accounts, but could create their own accounts on the Hub linked to their GitLab account. GitLab authentication not using gitlab_group_whitelist is unaffected. No other Authenticators are affected.)
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Analysis
by VulDB Data Team • 02/08/2023
The vulnerability identified as CVE-2018-7206 affects Project Jupyter JupyterHub OAuthenticator versions 0.6.x prior to 0.6.2 and 0.7.x prior to 0.7.3, representing a significant access control flaw that undermines the security of authentication mechanisms. This issue specifically impacts deployments utilizing GitLab group whitelisting for access control within JupyterHub environments, creating a scenario where unauthorized users can bypass intended restrictions and gain account creation privileges. The flaw resides in the OAuthenticator component's handling of GitLab group membership validation, where the system fails to properly verify that users belong to the specified whitelisted groups before permitting account creation on the JupyterHub platform.
The technical nature of this vulnerability stems from improper implementation of group membership checks during the authentication process, which aligns with CWE-284 Access Control Flaws and specifically manifests as an authorization bypass. When users authenticate through GitLab with group whitelisting enabled, the system should validate that the authenticated user belongs to one of the configured whitelisted groups before allowing account creation. However, the vulnerability allows users who are not members of the specified whitelisted groups to successfully create accounts on the JupyterHub system while still being restricted from accessing other users' accounts. This creates a situation where unauthorized individuals can establish their own accounts linked to their GitLab credentials, potentially leading to unauthorized system access and resource consumption.
The operational impact of this vulnerability extends beyond simple account creation privileges, as it fundamentally undermines the intended security boundaries of JupyterHub deployments that rely on GitLab group membership for access control. While the system correctly prevents users from accessing other accounts, the ability to create accounts represents a significant security gap that could be exploited by malicious actors or unauthorized users seeking to establish presence within the system. The vulnerability affects organizations that depend on GitLab group-based access control for their JupyterHub implementations, potentially allowing individuals who should not have access to create accounts and potentially consume system resources or gain unauthorized access to computational resources. This issue particularly impacts academic and research environments where JupyterHub is commonly deployed for collaborative data science and machine learning workloads, where unauthorized access could compromise sensitive research data or computational resources.
Organizations affected by this vulnerability should prioritize immediate remediation by upgrading to OAuthenticator versions 0.6.2 or 0.7.3, respectively, which contain the necessary fixes for proper group membership validation. The mitigation strategy should also include reviewing existing JupyterHub configurations to ensure that GitLab group whitelisting is properly implemented and validated. Security teams should consider implementing additional monitoring controls to detect unauthorized account creation attempts and establish proper access control policies that align with the principle of least privilege. The vulnerability demonstrates the importance of proper authentication and authorization validation in multi-factor authentication systems and highlights the need for comprehensive security testing of third-party components used in enterprise environments. This issue also aligns with ATT&CK technique T1078 Valid Accounts, as it allows unauthorized individuals to establish legitimate-looking accounts within the system, potentially enabling further malicious activities. Organizations should also consider implementing network segmentation and access controls to limit the impact of unauthorized account creation and ensure that any compromised accounts cannot easily escalate privileges or access sensitive resources within the broader system infrastructure.