PDFalerts

IT security professional Didier Stevens has highlighted a potential exploit in PDF Stream Objects which could be used to cause a PDF file to balloon in size, prompting Computerworld to label it the ‘PDF equivalent of the Zip bomb, or a PDF Bomb’.

Using filter parameters and filter cascading Stevens was able to create document that was only 2642 bytes in size, but when opened, decompressed to 1GB of data. This, as you can probably imagine, would cause some PDF readers to freeze up.

I recommend reading some of Didier Stevens other posts on security issues in PDFs as well.

Check out this video demo of viewing ebooks (in PDF format) on the iPhone. It looks pretty cool.

Cerience has announced its plans to release the world’s first native PDF viewer for BlackBerry.

RepliGo Reader will provide basic PDF viewing functionality such as zooming in and out of documents and  intelligently reformatting pages to fit the width of your BlackBerry screen. In addition, bookmarks, hyperlinks and searching will also be supported.

You can signup for the beta program of RepliGo Reader on this page.

Creating a link to a PDF on your website or blog is pretty straight forward as long as you are able to upload files to the hosting server. Once the PDF file has been uploaded it’s simply a matter of linking to where the PDF is located and your web browser will take care of the rest, there is no magic trick to it.

If you have your own domain then doing this is relatively simple — just upload the PDF to your root directory or a sub-directory and format your links like the below, depending on where the file is located:

root directory —> http://www.mydomain.com/mytodolist.pdf
sub-directory —> http://www.mydomain.com/files/mytodolist.pdf

The biggest problem with linking to PDFs from blogs is that not all blogging services allow you to upload files, but if they do, it’s simply a matter of linking to wherever the file has been uploaded to. You should also take into account the usability aspects of linking to PDFs on your website — read one of my previous posts about putting PDF links on web pages.

As for what happens when a user clicks on one of these links, that depends on which PDF reader they have installed. If they have Adobe Reader installed then the PDF will by default open in the browser (which can be a bit of a headache), but if they have something like Foxit Reader, or no PDF reader installed, then they will simply be prompted to download the file to their desktop.

The release of Adobe Acrobat 8.1 has been announced by Lori DeFurio on her Adobe Blog. This minor release includes support for Windows Vista, Office 2007 and 64-bit Citrix and Windows environments. The update is apparently available as of today, but so far the check for updates function in my Acrobat installation hasn’t picked up anything.

There are no real surprises in this release, but there is a feature that might get some Outlook 2007 users excited. According to Lori:

“Now, when you open an email message in preview mode that has a PDF attachment – you see the PDF in the preview pane. You can view full page, or page width, and even navigate multi-page files.”

Cool.

I was amused by this comment in her post:

The 8.1 release works with Microsoft Office 2007 and Microsoft Vista. Both PDF as a file format and Acrobat as an application are now “first class” citizens in these environments.

So the PDF file format is only a “first class” citizen of Vista, now that Adobe have got their act together, 4 months after the consumer release of Vista, and released a Vista compatible version of Acrobat 8? Tell’em they’re dreaming.

Adobe Reader 8.1 is also available as of today.

My dislike for viewing PDFs inside an Internet browser grows every time a website finds a way to automatically bypass the PDF Download add-on that I have installed for Firefox and loads inside my browser. Don’t get me wrong. I am a big fan of the PDF format and use it whenever I can — but I just don’t like to use it in a way that affects the usability of my browser. I prefer to download the PDFs to my desktop and open them at a time of my choosing without my browser going AWOL.

The solution I’ve found is to just disassociate Firefox with any of the PDF viewers that I have installed, so that when it comes across a PDF on the web, it has no choice but to prompt me to save it to my desktop. To stop PDFs from loading up in your Firefox browser, follow these simple steps:

1. Go to the “Tools -> Options” menu
2. Select the “Contents” tab
3. Click on the “Manage” button in the “File Types” section
4. Enter “pdf” in the “Search” box
5. Select “Change Action…”
6. Change the current selection to “Save them on my computer” and click OK

The next time you click on a link to a PDF document Firefox should prompt you to download it to your desktop.

Given the plethora of PDF Creators that are out there, you might expect there to be quite a few options for free PDF Readers as well, but this isn’t the case. There really are only two stand out options. The first option, Adobe Reader, is king of the mountain and has been around, in it’s current free form, since 1994. The second option, Foxit Reader, is a relative new comer and has developed a large following in a short period of time.

Adobe Reader. It wouldn’t be unfair to say that Adobe Reader is the most stable and reliable PDF Reader out there. Why? Two simple reasons spring to mind — 1) it’s developed by the masters of the PDF specification, 2) it’s been around for over a decade. The two downsides of Adobe Reader, which are a favorite pet peeve of many a forum frequenter, are that the installer for Adobe Reader is somewhat large (circa 20 MB) and the application load times can be slow in certain environments. But to be fair — the file size is becoming less of a concern for many people as Internet connections get faster and Adobe have been making a concerted effort to speed up the loading speed.

Download Adobe Reader here: http://www.adobe.com/products/acrobat/readstep2.html

Foxit Reader. This application hasn’t be around for long but it has gained a large cult following fast. If you have a quick search on Google Groups for PDF Reader, you’ll see what I mean. It’s key selling points are that it uses a really small installer (1.67 MB), it loads quickly and it isn’t developed by a behemoth corporation.

Download Foxit Reader here: http://www.foxitsoftware.com/pdf/rd_intro.php