The ICAO/IATA dangerous goods regulations for alcoholic beverages as passenger baggage, do not specify whether the bottle must not be opened. Security rules which are not dangerous goods regulations, May have differing rules. For instance, due to 9/11, flights to/from or through the U.S. forbids liquid unless they are less than 100mL and is carried in a clear plastic bag.
Security rules differ with each airline, and there May be some differences. The ICAO/IATA Dangerous Goods Regulations do not specify whether the bottles should not be opened. From common sense, if you are carrying an opened bottle in checked baggage, you will securely seal the bottle to prevent leakage.
For cabin baggage, it is cust Mar that a passenger would ask the cabin crew for beverages and drink from aircraft stock and would seldom drink from his own bottle. Chances are that the passenger’s bottle would be unopened however there is no such requirement in the ICAO/IATA rules prohibiting an opened bottle. It is better to inquire the airline for their anti-terrorist rules.