25.3.1 Basic Attacks
Two basic attack models, introduced originally in [12], are the random and average attack models. Both of these attacks involve the generation of profiles using
randomly assigned ratings to the filler items in the profile.
25.3.1.1 Random Attack
Random attack profiles consist of random ratings distributed around the overall
mean assigned to the filler items and a prespecified rating assigned to the target
item. In this attack model, the set of selected items is empty. The target item it is
assigned the maximum rating (rmax) or the minimum rating (rmin) in the case of push
or nuke attacks, respectively.
The knowledge required to mount such an attack is quite minimal, especially
since the overall rating mean in many systems can be determined by an outsider
empirically (or, indeed, may be available directly from the system). However, this
attack is not particularly effective [12, 6].
25.3.1.2 Average Attack
A more powerful attack described in [12] uses the individual mean for each item
rather than the global mean (except for the pushed item). In the average attack, each
assigned rating for a filler item corresponds (either exactly or approximately) to the
mean rating for that item, across the users in the database who have rated it.