OK, hereīs what I wanted to write first:
Not in this case, but itīs a
very understandable misunderstanding: Itīs a super confusing use of the terms
Attack (Attribute),
rating and
Attack rating 
Note that the first snippet does not really use the term
Attack rating. Itīs talking about the "ratings" of the different Matrix Attributes (one of which is called
Attack) in relation to the "rating" of the host. So the "rating" of the Hostīs Attack Attribute could be Host rating +1, +2 etc. BUT thatīs not the same as the "Attack rating" in the second snippet. Itīs a poor choice of words that gives that impression.
The second snippet talks about the actual mechanical term
Attack rating. Thatīs the value that is used when the hostīs IC attacks a target to determine who gets Edge. So, the IC uses host rating*2 to perform the Attack and to determine Edge gain. If it hits, thatīs when the
Attack Attribute of the host comes into play...
And
thatīs when I looked into my nearby copy of the German rulebook to realize that the last sentence is, in fact, not true: IC damage is based on the host rating as well, and the Attack Attribute(!) is never ever even used.
And
thatīs when I looked into the
Errata file to find this:
"Replace the second sentence with the following:
All IC use (Host Rating x 2) for Attack Rating, Condition Monitor, and most rolls." (so, the same sentence jtkirk22 posted)
And thatīs when I got mad-curious and looked into
both the old and the updated version of the English Core rule book. And lo and behold!
Old version of the CRB: "All IC use (Host Rating x 2) for Attack Rating, Condition Monitor, and most rolls." (Again, the same sentence sjtkirk22 posted. The Errata doesnīt change anything about it!)
New version of the CRB: "All IC use Host Attack Rating and (Host Rating x 2) for Condition Monitor and most rolls. (So, the non-change in the Errata file turned into an
actual change in the updated version).
*Rubs temples* The absolute effing state of editing...
So,
assuming that the updated version of the CRB is the final one to go with:
- IC attacks with a dice pool of (host rating) x 2
- Uses the Hostīs Attack Attribute as the Attack rating to determine Edge gain (unlike personas, who use Attack + Sleaze)
- IC damage is based on the hostīs base rating (unlike Data Spikes, where itīs Attack/2).
Phew...