🛡️ Efw Framework Security Mechanism

The analysis integrates the six main server-side components provided (efwServlet.java, efw.server.js, uploadServlet.java, previewServlet.java, downloadServlet.java, and efwFilter.java) to summarize the Efw framework’s security.

The Efw framework provides a robust enterprise application environment by incorporating multiple, specific security checks at the layers of screen access, event execution, and file I/O.

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1. Screen Access Control Layer (efwFilter.java)

efwFilter is the front-line security gateway that intercepts all requests for important resources (JSPs, various servlets).

• JSP Access Control: Checks login status and authorization at the Java level for direct access to JSP pages.
  • Login Check: If the login key does not exist in the session when accessing a JSP that requires authentication, the user is forcefully redirected to loginUrl, preventing unauthenticated access.
  • JSP Authorization Check: Even after login, if the user’s authority pattern (authPattern) does not match the access URL pattern (urlPattern), the user is forcefully redirected to systemErrorUrl, preventing navigation to unauthorized screens.
• Event Endpoint Passthrough: Endpoints like /efwServlet and the file I/O servlets pass through the filter, but without redirection checks, delegating authentication and authorization to the respective servlet or JS layer.

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2. Event Execution & Authorization Layer (efw.server.js)

The event execution (AJAX request) pipeline is protected by dedicated logic within server-side JavaScript.

• Login Check (checkLogin): Detects session timeout and instructs the client to display an alert and navigate to loginUrl.
• Authorization Check (checkAuth): Compares the executing eventId with the user’s authority in the session, preventing the execution of unauthorized functions.
• Decryption of Encrypted Data: If secure:true is set in the parameters, the server performs Base64 decoding, ensuring data confidentiality during communication.

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3. Data Quality & Validation Layer (efw.server.js)

Strict quality checks and sanitization are performed on input data before business logic execution.

• Server-Side Validation (checkStyle):
  • Type Safety: Based on format, data (dates, numbers, etc.) format is validated and converted to a safe data type before being passed to the logic layer.
  • Range/Length Check: Enforces min/max and max-length.
  • Prohibited Character Handling: Based on settings, dangerous or special characters in the input value are replaced/deleted, reducing the risk of data injection.

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4. File I/O Control Layer (Dedicated Servlets)

Because file processing carries high risk, specific security measures are enforced by Java within the dedicated servlets.

A. File Upload (uploadServlet.java)

Multi-layered access control and risk mitigation are performed at the earliest stage of upload.

• Enforced Upload Privilege: Even after passing through efwFilter, uploadServlet only accepts files from users with the uploadable=true privilege.
• Directory Traversal Prevention: The file name and upload path are strictly checked for .. (parent directory traversal) or illegal path characters, preventing unauthorized access to the file system.
• Temporary File Management: Files are first saved to a secure temporary area before being passed to the persistence logic (elfinder_upload.js).

B. File Provision Control (previewServlet.java, downloadServlet.java)

A mechanism is employed to prevent file path leakage during file retrieval.

• Path Secrecy via Session: File paths are passed via the HTTP session instead of URL parameters. This significantly reduces the risk of paths being guessed.
• Immediate Attribute Deletion: File information (file path, options) is immediately deleted from the session after the servlet retrieves it.
• Resource Restriction (previewServlet): File size is limited to 10MB during preview to prevent Denial-of-Service (DoS) attacks and server load increase.
• Resource Cleanup (downloadServlet): Generated temporary ZIP files and optionally configured source files are reliably deleted after the download is complete.

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Integrated Security Strategy

The Efw framework’s security strategy is based on the following three principles:

1. Defense in Depth: Establishing independent checkpoints at every layer: screen, event, data, and file I/O.
2. Role Delegation: Low-risk control is assigned to JavaScript, while high-risk control (JSP access, file I/O, path checks) is assigned to Java Servlets.
3. Session Usage: The transfer of highly sensitive information (file paths, login status) is conducted via the highly secure Session rather than the URL.