This Week's Sponsor:

Listen Later

Listen to Articles as Podcasts

How To Prevent iOS From Automatically Loading PDFs [Vulnerability]

Last night JailbreakMe was released in the wild. As we reported, it’s one of the simplest jailbreak tools ever made, as it requires only one slide in Mobile Safari to install Cydia on your device. You visit a link, slide, and wait. As we also reported, though, the exploit seems to based on a PDF vulnerability in iOS: the iPhone automatically downloads PDF files, and Comex injected the jailbreak code in a PDF file.

Update #1: It’s not a PDF header issue, it’s the FlateDecode stream section.

Update #2: Charlie Miller says it’s not the FlateDecode stream section either (the bug Huang suggested it’s in Adobe’s renderer, not Apple’s), it’s a PDF font bug: [via DF]

“Starting to get a handle on exploit. Very beautiful work. Scary how it totally defeats Apple’s security architecture.”

Like I said, it’s pretty great for jailbreakers - but for “normal” people and Apple this is a serious threat to security.

So now that you’ve jailbroken your device, wouldn’t it be best to fix this hole, in order to prevent malicious softwares to land on your phone by using the same technique?

[Check out for our full Cydia / Jailbreak coverage]

Tweeted by @cdevwill earlier today, all you have to do is download this .deb file and open it on your device using either Terminal from your Mac, or iFile on the iPhone. Just download it and place it in /var/mobile.

- Using Terminal:

ssh root@your IP address


dpkg -i file.deb

Where “alpine” is the default password you’ll get after installing Open SSH from Cydia and “your IP address” is located under Settings - > Wifi - > active wifi connection.

- Using iFile:

Navigate to /var/mobile and double tap on the .deb file to install it.

Please be aware that this won’t fix the issue, but it’ll simply ask you if you really want to open a .PDF every single time. If the source is trusted, you can confirm. But if you happen to visit a website that tries to install malicious stuff on your iPhone using @comex’s method, then you’ll be able to kill it.

Apple will surely address the bug in a future iOS release, but if you want to be safe right now - give it a try.

Unlock More with Club MacStories

Founded in 2015, Club MacStories has delivered exclusive content every week for over six years.

In that time, members have enjoyed nearly 400 weekly and monthly newsletters packed with more of your favorite MacStories writing as well as Club-only podcasts, eBooks, discounts on apps, icons, and services. Join today, and you’ll get everything new that we publish every week, plus access to our entire archive of back issues and downloadable perks.

The Club expanded in 2021 with Club MacStories+ and Club Premier. Club MacStories+ members enjoy even more exclusive stories, a vibrant Discord community, a rotating roster of app discounts, and more. And, with Club Premier, you get everything we offer at every Club level plus an extended, ad-free version of our podcast AppStories that is delivered early each week in high-bitrate audio.

Choose the Club plan that’s right for you:

  • Club MacStories: Weekly and monthly newsletters via email and the web that are brimming with app collections, tips, automation workflows, longform writing, a Club-only podcast, periodic giveaways, and more;
  • Club MacStories+: Everything that Club MacStories offers, plus exclusive content like Federico’s Automation Academy and John’s Macintosh Desktop Experience, a powerful web app for searching and exploring over 6 years of content and creating custom RSS feeds of Club content, an active Discord community, and a rotating collection of discounts, and more;
  • Club Premier: Everything in from our other plans and AppStories+, an extended version of our flagship podcast that’s delivered early, ad-free, and in high-bitrate audio.