4 ms·

Is there something like this for formats other than ZIP like jpeg or pdf?

jwilk 4y ago
For tar: https://github.com/ferivoz/alquitran https://github.com/ferivoz/alquitran
_vvhw 4y ago
I wanted to do this for those formats in particular, as well as Office files. Fastmail were going to sponsor some of this work to extend Pure, and I was chatting with the folks at Hey, but I couldn't get enough other sponsors to fund the work. The idea is to use Pure to have a "Zero-Day Defense Mode" button for your email provider that you can push, if you want static analysis on 90% of the file formats coming and going, so that you can have stronger assurance on email attachments that you open. For example, I believe that Pure would have prevented last year's zero-click traversal against Apple Mail. There are also so many ways to use file format anomalies to take out AV engines, so Pure can act as a first line of defense, before hostile data gets to them. For example, protecting them from the David Fifield zip bomb. What I find most interesting with these checks, is that they're looking for explicit bleeds or explicit overflow bounds. So the signal to noise ratio is high. Mostly, if people are interested, I would really love to move this all to Zig, to benefit from the checked arithmetic and spatial safety, since otherwise everything is all single-threaded run-to-completion.
- deleted 4y ago
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tgv 4y ago
Idk, but there's an interesting project, wuffs: a programming language specifically aimed at efficiently and safely parsing document structure. There is a PNG decoder [2]. 1. https://github.com/google/wuffs https://github.com/google/wuffs 2. https://news.ycombinator.com/item?id=26714831 https://news.ycombinator.com/item?id=26714831
_vvhw 4y ago
PDF is also a minefield, for how many ways there are to mess with the format: https://blog.didierstevens.com/2008/04/29/pdf-let-me-count-the-ways/ https://blog.didierstevens.com/2008/04/29/pdf-let-me-count-t...

For tar: https://github.com/ferivoz/alquitran https://github.com/ferivoz/alquitran

I wanted to do this for those formats in particular, as well as Office files. Fastmail were going to sponsor some of this work to extend Pure, and I was chatting with the folks at Hey, but I couldn't get enough other sponsors to fund the work. The idea is to use Pure to have a "Zero-Day Defense Mode" button for your email provider that you can push, if you want static analysis on 90% of the file formats coming and going, so that you can have stronger assurance on email attachments that you open. For example, I believe that Pure would have prevented last year's zero-click traversal against Apple Mail. There are also so many ways to use file format anomalies to take out AV engines, so Pure can act as a first line of defense, before hostile data gets to them. For example, protecting them from the David Fifield zip bomb. What I find most interesting with these checks, is that they're looking for explicit bleeds or explicit overflow bounds. So the signal to noise ratio is high. Mostly, if people are interested, I would really love to move this all to Zig, to benefit from the checked arithmetic and spatial safety, since otherwise everything is all single-threaded run-to-completion.

deleted 4y ago
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tgv 4y ago

Idk, but there's an interesting project, wuffs: a programming language specifically aimed at efficiently and safely parsing document structure. There is a PNG decoder [2]. 1. https://github.com/google/wuffs https://github.com/google/wuffs 2. https://news.ycombinator.com/item?id=26714831 https://news.ycombinator.com/item?id=26714831

_vvhw 4y ago

PDF is also a minefield, for how many ways there are to mess with the format: https://blog.didierstevens.com/2008/04/29/pdf-let-me-count-the-ways/ https://blog.didierstevens.com/2008/04/29/pdf-let-me-count-t...