[RPG] How do attack bonuses affect special attacks with combat maneuvers

In Pathfinder, certain creatures have special attacks that allow them a free combat maneuver when they succeed on an attack with one of their natural weapons. The abilities I had in mind are grab and trip, which are free action combat maneuvers.

I am not referring to the standard-action grapple and trip maneuvers. These special attacks are always linked to a natural weapon. In a way, they are part of the attack. This has led to some confusion about which attack roll adjustments also apply to the maneuver roll.

Are these maneuvers (grapple check from grab, and trip roll from trip) considered as attacks, implying that they are adjusted by attack roll adjustments?

Interpretation 1: They are combat maneuvers, but not attacks, thus they do not benefit from attack bonuses or penalties.

This seems to be what the combat rules suggest, because attack rolls and maneuver rolls are separate. Despite the term "special attack," the maneuver is not really an attack. The maneuvers are affected by bonuses that specifically mention CMB or maneuvers, such as the roll penalty when using Power Attack on your turn.

Because the free grab and trip are not attacks, the CMB rolls are not affected by attack bonuses that don't explitcitly mention CMB or maneuvers (such as charging, flanking, Weapon Focus, the enhancement bonus from an Amulet of Mighty Fists, and so on).

Interpretation 2: They are combat maneuvers and attacks, thus they DO benefit from attack bonuses or penalties.

The term "special attack" implies that grab and trip are attacks. In this case, even though it's an attack, you still make a CMB check versus the target's CMD. But the roll would benefit from any bonus to the corresponding natural weapon's attack roll. Any bonus to your attack rolls, even if it does not mention CMB or combat maneuvers, also applies to the grab and trip maneuvers.

Which interpretation is correct? As far as I understand them, they seem to contradict each other.