Prolly...
Daylight + white + exposure would do it.
The reason I don't think there was a flash used is because of the lack of detail or light in and around the guy's helmet, or under its straps. But yeah, a flash isnt even required to produce the whiteness of the cig.
Not only that... but the guy's mouth is in natural cig-gripping form. Not impossible to fake by any means, but far more would do it wrong than do it right. And when ya see the quality of P'shop work done when there isn't any money involved (me included), it usually doesn't cut the mustard. I can't imagine why anyone would go to the lengths to make it perfect.