Simon Willison’s Weblog

Thursday, 16th December 2021

Weeknotes: Trapped in an eternal refactor

I’m still working on refactoring Datasette’s table view. In doing so I spun out a new plugin, datasette-pretty-traces, which improves Datasette’s tooling for seeing the SQL that was executed to build a specific page.

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A deep dive into an NSO zero-click iMessage exploit: Remote Code Execution (via) Fascinating and terrifying description of an extremely sophisticated attack against iMessage. iMessage was passing incoming image bytes through to a bunch of different libraries to figure out which image format should be decoded, including a PDF renderer that supported the old JBIG2 compression format. JBIG2 includes a mechanism for programatically swapping the values of individual black and white pixels... which turns out to be Turing complete, and means that a sufficiently cunning “image” can include a full computer architecture defined in terms of logical bit operations. Combine this with an integer overflow and you can perform arbitrary memory operations that break out of the iOS sandbox. # 8:33 pm

2021 » December