JeecgBoot Tenant Privilege Escalation Vulnerability Explained

Unveiling a Critical Vulnerability in JeecgBoot

In the realm of web application security, tenant privilege escalation is a particularly insidious threat. It allows unauthorized users to access data belonging to other tenants, which can have severe consequences, including data breaches, privacy violations, and even facilitating further targeted attacks. Today, we're diving deep into a specific vulnerability found in JeecgBoot, an open-source low-code development platform. This vulnerability, concerning the GET /sys/position/getPositionUserList endpoint, allows an attacker to query position members without proper tenant validation, leading to a significant cross-tenant information disclosure. The official repository for JeecgBoot can be found at https://github.com/jeecgboot/jeecg-boot, and this issue affects the latest versions of the platform. Understanding how this happens and how to fix it is crucial for anyone using or developing with JeecgBoot.

The Vulnerable Endpoint and Its Functionality

The heart of this vulnerability lies within the GET /sys/position/getPositionUserList API endpoint. This endpoint is designed to retrieve a list of users associated with a specific position within the system. When a user requests information for a particular positionId, the system is supposed to return details about the members holding that position. However, as we'll explore, the implementation of this endpoint in JeecgBoot fails to adequately check if the requested positionId actually belongs to the tenant of the currently authenticated user. This oversight creates a gaping hole that attackers can exploit to gain access to sensitive data they should never see. The parameters typically used are positionId to identify the target position, and pageNo and pageSize for pagination, ensuring that large lists of users can be retrieved efficiently. In a secure system, the positionId would be cross-referenced with the current user's tenant ID to ensure data isolation. The absence of this check is the root cause of the problem.

Deep Dive into the Code: Where the Vulnerability Hides

To truly grasp the mechanics of this privilege escalation, let's dissect the relevant code. The vulnerable code resides within the SysPositionController.java file, specifically in the jeecg-boot/jeecg-module-system/jeecg-system-biz/src/main/java/org/jeecg/modules/system/controller/SysPositionController.java. The endpoint in question is exposed via a GET request at /getPositionUserList. The controller method, getPositionUserList, accepts pageNo, pageSize, and crucially, positionId as request parameters. The problematic logic begins around lines 358 to 373. Here, a Page object is instantiated with the provided pagination details. Then, the userPositionService.getPositionUserList method is called, passing the page object and the positionId. The core issue arises immediately after: the code retrieves the user IDs from the returned records and then proceeds to fetch additional user details, such as their department name (orgCodeTxt), using userService.getDepNamesByUserIds. The critical flaw is that the positionId is used directly to query user information without any validation to ensure this position belongs to the current user's tenant. This means if an attacker can guess or enumerate a positionId from another tenant, they can successfully retrieve user data associated with that position, effectively bypassing tenant segregation.

The Mechanics of Exploitation: Reproduction Steps

Reproducing this vulnerability is straightforward for an attacker who has a valid login session within the JeecgBoot application. The prerequisites are simple: the attacker needs to be logged in, possess or be able to enumerate a positionId belonging to a different tenant, and the system must have the position management functionality enabled, which is a standard feature. The exploitation involves a simple curl command or any HTTP client. An attacker, logged in as a user from Tenant A, would craft a request like this: curl -X GET -H "Authorization: Bearer <attacker_token>" "http://<host>/jeecgboot/sys/position/getPositionUserList?positionId=<victim_position_id>&pageNo=1&pageSize=100". Here, <attacker_token> is the attacker's authentication token, and <victim_position_id> is a positionId known or guessed to belong to a different tenant (e.g., Tenant B). Upon sending this request, the API will respond with a 200 OK status. The response body will contain a list of users associated with the victim_position_id, including sensitive details such as User ID (id), Username (username), Real Name (realname), and Department Name (orgCodeTxt). This demonstrates a clear cross-tenant personnel information disclosure. To verify the breach, one could compare the results with what an administrator from Tenant B sees for the same position or directly query the sys_user_position association table in the database to confirm data ownership and access.

The Devastating Impact of Cross-Tenant Data Leakage

The consequences of this JeecgBoot vulnerability are far-reaching and can inflict significant damage. Primarily, it leads to cross-tenant personnel information disclosure. Attackers can obtain a treasure trove of sensitive data about employees from other organizations using the same JeecgBoot instance. This includes their real names, usernames, and departmental affiliations. Such a breach is not just a technical failure; it's a serious invasion of user privacy and can lead to violations of data protection regulations like GDPR or CCPA, resulting in hefty fines and reputational damage. Beyond individual privacy, the vulnerability exposes the organizational structure of other tenants. By correlating positions with the personnel holding them, an attacker can infer how different departments are staffed and understand the hierarchy and allocation of resources. This intelligence is invaluable for malicious actors. It significantly provides intelligence for social engineering attacks. Armed with real names, positions, and potentially other leaked attributes, attackers can craft highly convincing phishing emails or social engineering schemes to trick employees into revealing more sensitive information or granting unauthorized access. Furthermore, the leakage of usernames can facilitate account enumeration. Attackers can build a list of valid usernames within other tenants, which can then be used as targets for brute-force attacks or credential stuffing attempts, further compromising the security of other organizations. The cascading effect of this vulnerability underscores the importance of robust tenant isolation in multi-tenant applications.

Fortifying JeecgBoot: Essential Remediation Strategies

Addressing the JeecgBoot tenant privilege escalation vulnerability requires a multi-layered approach, focusing on robust validation and access control. The most direct remediation is to implement position tenant ownership validation. Before querying any position details or associated users, the system must verify that the positionId belongs to the current user's tenant. This can be achieved by retrieving the SysPosition object using sysPositionService.getById(positionId) and then comparing its tenantId with the currentUser.getTenantId(). If they don't match, access should be denied with an appropriate error message, such as "Unauthorized to access this position data". This check should ideally happen early in the request handling process, preferably in the controller. Another crucial step is force tenant filtering within the Service layer. Even if the controller validation is bypassed or deemed insufficient, the getPositionUserList method in the service layer should inherently filter results based on the current tenant's ID, ensuring that only data pertaining to the authenticated tenant is ever processed or returned. Complementing these validation steps, data desensitization should be applied to sensitive user information. For instance, phone numbers or email addresses, if exposed by other endpoints, should be masked or redacted unless explicitly needed and permitted. The level of detail returned should be based on the querier's permissions. Implementing strict permission level control is also vital. Only users with specific roles, such as HR administrators or department heads, should be granted the privilege to view detailed position member lists. For all other users, this capability should be restricted. Finally, comprehensive audit logging is essential. Every operation that queries position member lists should be logged, including the user performing the query, the positionId queried, and the timestamp. This allows for the monitoring of abnormal query behavior, such as an account attempting to query a large number of different positions in a short period, which could indicate an ongoing attack. By implementing these remediation strategies, organizations can significantly enhance the security posture of their JeecgBoot applications and protect against sensitive data leakage.

Conclusion: Prioritizing Tenant Security

The vulnerability in JeecgBoot's GET /sys/position/getPositionUserList endpoint highlights a critical security principle: tenant isolation must be rigorously enforced in multi-tenant applications. The failure to validate positionId against the current tenant's ID allows for the straightforward disclosure of sensitive personnel information, posing significant risks to privacy, organizational integrity, and overall security. By implementing the suggested remediation steps—robust tenant ownership validation, service-level filtering, data desensitization, stringent permission controls, and comprehensive audit logging—developers can effectively patch this vulnerability and safeguard their applications. Regular security audits and staying updated with the latest security patches are paramount in maintaining a secure environment. For further insights into securing your applications, you might find valuable information from resources like the OWASP Foundation.