Edit: to the iudqnolq's reply below - warrant doesn't have to explicitly permit it. My understanding [IANAL] is that, at least in the physical world, whatever gets in "plain view" of the officer during any authorized law enforcement activity also becomes a fair game. I.e. they were called for the noise and upon entering see a kilo of heroin laying on the table - the heroin comes into play even though they didn't have a search warrant for it. So i'd expect that the same principle would be applicable in the virtual world too.
If it isn’t passively visible, it is not, by definition, in plain view. If they have to do a search, however simple, beyond what is explicitly authorized in the warrant, to find the information or to find whatever would give them probable cause to believe it is contraband or evidence of crime, they can neither seize it nor get a search/seizure warrant based on their observation of it under the plain view doctrine.
This warrant does not authorize the seizure of any tangible property. Except as provided above, this warrant does not authorize the seizure or copying of any content from the electronic storage media identified in Attachment A or the alteration of the functionality of the electronic storage media identified in Attachment A."
https://www.justice.gov/opa/press-release/file/1386631/downl...