Need

Restriction of user privileges to prevent unauthorized access and modification of permissions

Context

• Usage of Java 8 for developing applications with enhanced features and performance
• Usage of javax.servlet-api for developing Java web applications with Servlets
• Usage of SharePointAPI for interacting with SharePoint services and data

Description

Non compliant code

        import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import javax.servlet.ServletException;

public class VulnerableServlet extends javax.servlet.http.HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String groupName = request.getParameter("groupName");
        String user = request.getParameter("user");
        boolean isAdmin = Boolean.parseBoolean(request.getParameter("isAdmin"));

        SharePointGroup group = SharePointAPI.createGroup(groupName);
        SharePointAPI.addUserToGroup(user, group);

        if(isAdmin) {
            SharePointAPI.setAdminPrivileges(user, group);
        }
    }
}
        
        

The above code represents a Servlet that handles HTTP POST requests. The Servlet gets parameters from the request, namely groupName, user, and isAdmin.

The groupName parameter is used to create a new group in the SharePoint platform via the SharePointAPI.createGroup(groupName) method.

The user parameter represents the username of a user. This user is then added to the newly created group using the SharePointAPI.addUserToGroup(user, group) method.

The isAdmin parameter is a boolean value that if true, sets the user as an admin of the group using the SharePointAPI.setAdminPrivileges(user, group) method.

The vulnerability here is that there are no checks to see if the user making these requests has the necessary permissions to perform these actions. As a result, any user can create a group, add users to it, and even set any user as an admin of the group. This is a clear violation of the principle of least privilege, as users are able to perform actions that they should not have access to.

Steps

• Implement proper authentication and authorization mechanisms to ensure that only authorized users can access the application.
• Validate and sanitize all user input to prevent any malicious input from being executed.
• Implement the principle of least privilege, where users are only granted the minimum privileges necessary to perform their tasks.
• Review and update the SharePointAPI methods to ensure that they enforce proper access controls and permissions.
• Implement proper error handling to prevent error messages from leaking sensitive information or providing clues for attackers.
• Regularly update and patch the SharePoint platform to address any security vulnerabilities.
• Conduct regular security audits and penetration testing to identify and fix any potential vulnerabilities in the application.

Compliant code

        import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import javax.servlet.ServletException;

public class SecureServlet extends javax.servlet.http.HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String groupName = request.getParameter("groupName");
        String user = request.getParameter("user");
        boolean isAdmin = Boolean.parseBoolean(request.getParameter("isAdmin"));

        // Validate and sanitize user input
        groupName = InputValidator.sanitize(groupName);
        user = InputValidator.sanitize(user);

        // Check if the user is authenticated and authorized
        if(AuthenticationAPI.isAuthenticated(user) && AuthorizationAPI.isAuthorized(user, "createGroup")) {
            SharePointGroup group = SharePointAPI.createGroup(groupName);
            SharePointAPI.addUserToGroup(user, group);

            // Check if the user has admin privileges
            if(isAdmin && AuthorizationAPI.isAuthorized(user, "setAdminPrivileges")) {
                SharePointAPI.setAdminPrivileges(user, group);
            }
        } else {
            response.sendError(HttpServletResponse.SC_FORBIDDEN, "You are not authorized to perform this action.");
        }
    }
}
        
        

The updated code now includes proper authentication and authorization checks to ensure that only authenticated and authorized users can create groups and set admin privileges. The AuthenticationAPI.isAuthenticated(user) method checks if the user is authenticated, and the AuthorizationAPI.isAuthorized(user, "action") method checks if the user is authorized to perform a specific action.

User input is now validated and sanitized using the InputValidator.sanitize(input) method to prevent any malicious input from being executed.

The principle of least privilege is implemented by only granting admin privileges to users who are authorized to have them. If a user tries to set admin privileges but is not authorized to do so, the server will respond with a 403 Forbidden error.

The SharePointAPI methods should also be reviewed and updated to enforce proper access controls and permissions, and the SharePoint platform should be regularly updated and patched to address any security vulnerabilities.

Regular security audits and penetration testing should be conducted to identify and fix any potential vulnerabilities in the application.

References

• 159. Excessive privileges