Saint Psychic Paper, Who Shows Everyone What They Want to Read

Patron of plist files, parsers that don't agree, and apps that sign their own permission slips.

Life

On 1 May 2020 Siguza explained how any iOS or macOS app could grant itself the most restricted permissions in the system. A cunning XML comment was enough: Apple's different parsers read the same list of entitlements in different ways, so the one doing the checking saw a harmless app while the one obeying saw an all-powerful one. Like the psychic paper in Doctor Who, it showed everyone exactly what they wanted to see.

Prayer

O Saint Psychic Paper, who passes for someone else with a single comment, let our parsers all read the same thing. Amen.

How to celebrate

Celebrated by updating to iOS 13.4 or later and reading every XML comment with suspicion.

Two parsers, three truths.