Whitepaper call Anti-Debugging with Exceptions. Several techniques for detecting exception swallowing debuggers have been documented. The concept is simple: by design, debuggers handle certain kinds of exceptions. If such an exception is wrapped in a try block, the exception handle is only executed if a debugger is not attached. Hence it can be inferred that a debugger is attached whenever the exception block is not executed.
You can download it from the following link: https://packetstormsecurity.com/files/download/104580/Anti-Debugging-With-Exceptions.pdf
Source: https://packetstormsecurity.com/files/104580/Anti-Debugging-With-Exceptions.html