If the answer above is None it means there is no specific mention in the legislation, but you still need to ask local law enforcement before drinking in Brunei.
Non-Muslims over 17 years of age are allowed to import alcohol not to exceed maximum total volume 2 liters of liquor and 12 cans of beer at 330 ml for personal use, once in 48 hours. This alcohol must be “stored and consumed at the place of residence of the importer” and is “not to be given, transferred or sold to another person.”.
You can find more legal details and links here:
Wikipedia Legal Drinking Page