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50 CVEs in 50 Days: Fuzzing Adobe Reader

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Re: 50 CVEs in 50 Days: Fuzzing Adobe Reader

#161
post #160
post #118

Earlier quoted context omitted.

Adobe Reader is already sandboxed a la Chrome.

According to Zerodium prices, VM escape costs as much as LPE, so it is unclear if there will be much of a security improvement beyond 2x. Although virtual machine hypervisors don’t automatically update, unlike Adobe or Windows.

I am pretty sure that hypervisors update just like any other software, via the package manager.

Re: 50 CVEs in 50 Days: Fuzzing Adobe Reader

#162
post #102

Earlier quoted context omitted.

The Office formats are well specified, they are complex because that is the nature of the software but it is a world away from something like PSD or even PDF.

PDF is actually quite well specified, there are not many holes in the specification itself.[0] As to what Adobe Reader will do when it encounters an out-of-spec file, that is a lot fuzzier. On the other hand, the Office file formats (especially Word) have many un- or underspecified cases. [0] The only one I know of is finding the end of compressed inline image data.

I agree, the PDF spec is great, and very easy to understand (if slow to wade through). The hardest parts are when you have to duck out to read another spec for a contained format like TrueType.

Regarding Reader, I work with PDFs a lot, and the majority of issues have a fairly common pattern. The supplier has created a PDF in a 3rd party tool, which is invalid in a subtle way (production printers in particular are very specific about what they want to accept).

But it works fine in Adobe Reader, since it was built to be very tolerant in what it accepts, so it's often hard to convince the non-technical users that the file has an issue. It's great for end users but has meant that a lot of tools out there just didn't have to try too hard to make PDFs that mostly work, so programming workflows can be an issue.

Re: 50 CVEs in 50 Days: Fuzzing Adobe Reader

#163
post #121

Earlier quoted context omitted.

I don't know how accurate that is for PDF's, but webpages are supposed to look the same, and given known compatible styling, it should be on any modern browser. Browsers are extremely consistent in content presentation, that's why webpages from early 2000s still look the same.

> I don't know how accurate that is for PDF's, but webpages are supposed to look the same, One of Adobe's early talking points for the value of PDF's was that they would "look the same on all systems". Of course some context is necessary. PDF first appeared in 1993. In 1993, while the internet did exist, most individuals who were not associated with a university, research lab, or govt. agency, had no access to 'the i…

That was really informative, thank you. Given the same rendering on browsers across platforms I imagine you could achieve the same effect as PDF, but it would be a spec on top of html+css, not inherently built for documents like PDF is as you said. There may be some differences in important edge cases, but PDF would still exist for business that relies upon it in that manner. I'm talking more of a replacement that fits the 90% of cases that don't deal with signatures and legally bound documents and such.

Re: 50 CVEs in 50 Days: Fuzzing Adobe Reader

#164

Earlier quoted context omitted.

I don't know how accurate that is for PDF's, but webpages are supposed to look the same, and given known compatible styling, it should be on any modern browser. Browsers are extremely consistent in content presentation, that's why webpages from early 2000s still look the same.

What? Lot's of webpages look different after simply resizing the window! The fact that this is on purpose, doesn't mean it doesn't happen (quite the opposite!).

That's because they're designed that way. You can do styling in a way that is not effected by browser window sizing, typically with specified document dimensions, or absolute positioning.

Re: 50 CVEs in 50 Days: Fuzzing Adobe Reader

#165

Being able to run JS in a PDF sounds scary to a lot of people, but I wouldn't throw that idea out entirely. If you follow the work by Bret Victor & others on "explorable explanations"[0][1] and interactive scientific papers[2], you probably appreciate the need for a self-contained format for interactive documents. Could PDF be this? I don't know, I hear the spec is too scary. But I'd say we should have something like…

The same idea made the web the disaster it is today.

No, it didn't.

The same idea made the web. Commercialization of the web was what caused the disaster.

Re: 50 CVEs in 50 Days: Fuzzing Adobe Reader

#166

Earlier quoted context omitted.

I found quite a few areas that were vague when I was working with it. The advantage of the office formats is they are Zip files with a ton of XML, ie they are well defined. The application parts are another matter of course.

Just because something is XML doesn't mean it is "well-defined".

No, but XML parsing is a solved problem, PDF parsing isn't.

Re: 50 CVEs in 50 Days: Fuzzing Adobe Reader

#167
post #102

Earlier quoted context omitted.

PDF is actually quite well specified, there are not many holes in the specification itself.[0] As to what Adobe Reader will do when it encounters an out-of-spec file, that is a lot fuzzier. On the other hand, the Office file formats (especially Word) have many un- or underspecified cases. [0] The only one I know of is finding the end of compressed inline image data.

I found quite a few areas that were vague when I was working with it. The advantage of the office formats is they are Zip files with a ton of XML, ie they are well defined. The application parts are another matter of course.

I see. I was mostly referring to semantic problems, of which I heard there are a lot (I haven't really worked with Office internals much), and also I was thinking of the pre-XML Office formats.

Re: 50 CVEs in 50 Days: Fuzzing Adobe Reader

#168

Earlier quoted context omitted.

The same could be said for the Microsoft Office file formats. Or PSD, for that matter.

The Office formats are well specified, they are complex because that is the nature of the software but it is a world away from something like PSD or even PDF.

I remember reading in the past that Microsoft had corrupted the ISO standards body to publish essentially fake standards that were different to what MS Office actually produced, so software like Libreoffice would output files that didn't work properly in Office or visa versa. Are you saying that now this is not the case and they are full specified? I sometimes tell people about this so I want to make sure I have my facts straight.

Re: 50 CVEs in 50 Days: Fuzzing Adobe Reader

#169
post #36

The fact that companies still have the email-> employee pc -> acrobat reader pipeline enabled says a lot about what companies really think about security, posturing aside. (home users too, but they can plead ignorance)

I would be interested to hear the counterarguments to this.

Re: 50 CVEs in 50 Days: Fuzzing Adobe Reader

#170

It's amazing browsers have so far decided to just not have an HTML archive format that could replace PDF. The majority of what PDF does can be better done in a webpage. Why not just an extension like .phd but is actually a .tar.gz that contains a webpages assets. Present like pdf's are, and done.

PDFs are supposed to look the same on every computer. Webpages can’t do that yet.

Not with text markup, but you could just use canvas or svg.
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