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Session 2: Building a Secure File System MCP Server - Test Solutions

📝 Multiple Choice Test - Session 2

Question 1: What is the primary purpose of the sandbox in our file system server?

A) To improve performance
B) To prevent unauthorized file access ✅
C) To compress files
D) To cache file contents

Explanation: The sandbox is the critical security boundary that restricts all file operations to a designated directory, preventing access to sensitive system files and implementing defense-in-depth security.

Question 2: Which method is used to safely resolve file paths and prevent directory traversal attacks?

A) os.path.join()
B) Path.resolve() ✅
C) str.replace()
D) Path.absolute()

Explanation: Path.resolve() resolves all symlinks and normalizes paths (including .. components), which is essential for preventing directory traversal attacks like ../../../etc/passwd.

Question 3: How are binary files handled in the read_file tool?

A) Rejected with an error
B) Converted to hexadecimal
C) Encoded as base64 ✅
D) Read as UTF-8

Explanation: Binary files are encoded as base64 strings for safe transmission through the JSON-RPC protocol, since JSON cannot directly contain binary data.

Question 4: What type of validation is performed on file types for security?

A) Extension only
B) MIME type only
C) Both extension and MIME type ✅
D) File size only

Explanation: The server validates both the file extension (user-provided) and MIME type (content-based detection) to prevent disguised malicious files and ensure accurate file type identification.

Question 5: Which logging level is used for security violations in the file system server?

A) DEBUG
B) INFO
C) WARNING ✅
D) ERROR

Explanation: Security violations like sandbox escape attempts are logged at WARNING level to indicate suspicious activity that should be monitored but doesn't necessarily break the application.

Question 6: What happens when a file path attempts to escape the sandbox?

A) The server crashes
B) A SandboxError is raised ✅
C) The path is automatically corrected
D) Access is granted with a warning

Explanation: The server raises a SandboxError exception when paths attempt to escape the designated sandbox directory, providing a clear security boundary enforcement mechanism.

Question 7: Why does the server implement file size limits?

A) To save disk space
B) To prevent denial of service attacks ✅
C) To improve search performance
D) To maintain file quality

Explanation: File size limits prevent attackers from uploading extremely large files that could exhaust server memory or disk space, causing denial of service attacks.

Question 8: What approach does the server use for file type restrictions?

A) Blacklist dangerous extensions
B) Whitelist safe extensions ✅
C) Allow all extensions
D) Check file signatures only

Explanation: The server uses a whitelist approach, only allowing predefined safe file extensions, which is more secure than blacklisting dangerous extensions that can be easily circumvented.

Question 9: How does the search_files tool prevent performance issues?

A) By caching all file content
B) By limiting maximum results returned ✅
C) By using external search engines
D) By compressing search results

Explanation: The search tool implements result limits to prevent performance degradation when searching through large file sets, ensuring consistent response times.

Question 10: What is the primary benefit of using aiofiles for file operations?

A) Non-blocking file I/O operations ✅
B) Better error handling
C) Faster disk access
D) Automatic file compression

Explanation: aiofiles provides asynchronous file operations that don't block the event loop, allowing the server to handle multiple concurrent requests efficiently.

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