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.
3dc0d938444d4ea8c28a360c244944d839f70154ae1c34e649472052b970a2ef