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Re:Any page loaded in IE can track your mouse movements anyw... by meaty on Wednesday December 12, 2012 @09:21AM (#4910113)
Should documents be Turing complete?
Re:Any page loaded in IE can track your mouse movements anyw... by lmm on Wednesday December 12, 2012 @11:01AM (#4910687)
No, but even if we switched tomorrow, there are millions of legacy documents in Turing-complete formats that users want to access.
Re:Any page loaded in IE can track your mouse movements anyw... by Cthulhu_ on Wednesday December 12, 2012 @09:52AM (#4910284)
They don't need to be in order to have weaknesses; just look at all the security problems coming from Adobe's PDF reader, which afaik can't execute code, but where the input (PDF documents), if cleverly crafted, can create buffer overflows allowing for arbitrary code execution.
Re:Any page loaded in IE can track your mouse movements anyw... by pcwalton on Wednesday December 12, 2012 @12:07PM (#4911175)
PDF files actually can execute code [1]. In fact, there are not one but two JavaScript engines inside Adobe Reader!

[1]: http://stackoverflow.com/questions/9219807/using-javascript-...

Re:Any page loaded in IE can track your mouse movements anyw... by meaty on Wednesday December 12, 2012 @10:03AM (#4910340)
PDF files are code. They are a variant of postscript which is a Turing complete language. People have written web servers in postscript I understand.

The issue you state is a property of three things:

1. The underlying language/vm allows code and data to be interchanged (c++).

2. The underlying vm allows memory to be overwritten and buffer lengths to be exceeded to start with.

3. Pdf allows arbitrary code to execute on your computer.

My point demonstrated.

Re:Any page loaded in IE can track your mouse movements anyw... by ygra on Thursday December 13, 2012 @03:53AM (#4914929)
PDF is a very small subset of PostScript as a programming language, centered around objects that are usually in a compressed stream. Pages, text, images, drawings, etc. are all objects and appropriately linked¹. The language itself cannot really do more than creating objects and dictionaries; no programming is left.

Embedded JavaScript is another matter, but it's not needed to be executed for parsing the document.

_____________

¹ This gives rise to interesting applications, e.g. you can remove pages or images by just removing a link in the PDF. Yet the object would then still be there. There are some PDFs out there where sensitive information is buried in unlinked objects that still exist within the file. But that's obviously besides the point.

Re:Any page loaded in IE can track your mouse movements anyw... by Jacobi on Wednesday December 12, 2012 @10:03AM (#4910336)
The PDF document format is incredibly complex. It can incorporate JavaScript actions !
Re:Any page loaded in IE can track your mouse movements anyw... by ygra on Thursday December 13, 2012 @04:03AM (#4914956)
They are not needed to parse the file. PDFs can also contain Flash content or movies or 3D models or any number of other objects. It's just a blob in the file, same as OLE. Few applications beyond Adobe Reader care about implementing those parts, though.
Re:Any page loaded in IE can track your mouse movements anyw... by sukuriant on Wednesday December 12, 2012 @04:32PM (#4912588)
postscript is turing complete: http://www.tjhsst.edu/~edanaher/pslife/