Hacker News Reader

Comment by fouc | Hacker News Reader

>when Google reverse-engineered the hack used against American diplomats in Uganda, they found an elegant, tiny piece of code that adapted software from 1990s Xerox machines to fit a so-called Turing machine — essentially a complete computer — into a single GIF file.

LOL at describing PDFs as "adapted software from 1990s Xerox machines"

https://googleprojectzero.blogspot.com/2021/12/a-deep-dive-i...

View on HN

They were talking about JBIG2, not PDF.

JBIG2 has been in the news periodically for a different sort of problem - you can't trust it to accurately represent what was scanned:

https://www.theregister.com/2013/08/06/xerox_copier_flaw_mea...

The NSO exploit started by pretending to send a GIF, that was sent down to some decoder that did automatic file-type detection based on data rather than filetype and "correctly" detected an PDF, the Apple PDF decoder in turn supports JBIG2 images where the actual exploit lives.

Having spent some time with OCR and scanning recently, I'd have to agree.

A lot of news articles are describing JBIG2 as something archaic, when it seems to be as relevant and commonplace as ever. (see MRC, for a modern application)

The article was originally written for Financial Times, whose audience will have a general knowledge of computing. Also, what the heck is MRC?

Mixed raster content, I assume.

Basically, you scan a paper document. It contains a mixture of line art, text, and photographs—“mixed” types of content. You can segment it and use different codecs to encode these different segments, and then combine the results in a PDF.

News articles, plural. Eg, here is another story by way of Ars:

> Essentially, 1990's algorithms used in photocopying and scanning compression are still lurking in modern communication software, with all of the flaws and baggage that come with them.

https://arstechnica.com/information-technology/2021/12/googl...

Given than JBIG2 wasn't standardized until 2000, and that the Apple vulnerability was in their implementation (vs the standard) I just don't understand this characterization.

Reply on news.ycombinator.com