The Security Skeptic

Mac Users: Prevent Presentation Hijacking, Disable or Pair Your Remote Control

You're giving a conference talk. You're running presentation software from your MacBook. The talk is going extremely well. Suddenly, you lose control of the presentation. Slides change randomly. You regain control. You begin a movie clip, the volume suddenly changes to max, and your audience covers their ears. You minimize the presentation software to investigate. iTunes launches, chooses Fuel by Metallica. At max volume. Your audience heads for the exits.

Your trusty laptop hasn't grown a mind of its own. It's been hijacked by someone in the audience with a remote control infrared receiver.

A post at tumblr exposes how the default setting of remote control infrared receiver on a MacBook leaves any presenter vulnerable to such a hijack attack. Peter Payne writes:

"By default, all Macs that have remote controls work with any remote, so it’d be possible to make all the computers start playing iTunes music at once, go to the next frame (if they were open to an app like PowerPoint/Keynote), etc. It’s easy to tie your computer to a specific remote control or turn off the remote feature completely, but few people know to do this."

To avoid this embarrassment, either pair your Apple Remote with your MacBook, or disable the remote control infrared receiver.

1. Open System Preferences
2. Choose Security & Privacy
3. Click on the Lock icon and enter your password
4. Click the Advanced... button
5. If you want to pair your remote with your laptop, click Pair and follow these instructions
6. Check the box Disable remote control infrared receiver

If you have not already done so, this would be an excellent time to also check the box Require an adminstrator password to access locked preferences.

Thanks to Martin McKeay for Tweeting about this and providing me with this teaching moment.

How to re-open documents and windows when you re-open applications: OS X Lion and Mountain Lion

Some users prefer to have their applications open whatever documents or windows they left open when they last closed that application. Users who want to pick up where they left off in this manner will find that setting preferences to enable this behavior changes when they migrate from OS X Lion to OS X Mountain Lion.

First let's see how you do this. Then we'll discuss whether it's wise.

OS X Lion: Restore Windows when quitting and re-opening apps

Open System Preferences in OS X Lion.   Click the Show All button. Click the General icon. Check the box labeled Restore Windows when quitting and re-opening apps if you want to re-open all windows or documents when you re-launch applications.

OS X Mountain Lion: Close Windows when quitting an application

Open System Preferences in OS X Mountain Lion.   Click the Show All button. Click the General icon. (Pay attention to the negative logic here) Uncheck the box labeled Close Windows when quitting an application if you want to re-open all windows or documents when you re-launch applications.

Re-opening documents or windows may not be a good idea

When you takes advantage of this convenience feature, you run the risk of  re-visiting a malicious hyperlink, page, or document.  Users can end up in a closed loop of mischief of this kind:

• You open a browser, visit a web page
• A script on that page executes and some badness wrecks havoc on your Mac
• You quit the browser
• You discover and undo (remediate) the harm
• You re-launch the browser (a.k.a., lather-rinse-repeat)

By enabling this preference, you're permitting not only your browser but all applications to re-open the last or recent document or window. If you use MS Office, for example, you may re-open a Word document containing a nasty macro that arrived as an attachment, or a malicious PDF or Flash file with an Adobe product.

Before you enable this behavior, ask whether you want to open whatever you last opened, a favorite site, or (the safest course) start anew. Then explore whether you can accomplish what you want without the broad and potentially nefarious "allow any" preference. It's unfortunate that convenience features can put your Mac at risk, but now that you're aware, choose wisely.

(Note: Certain browsers have similar options or addons. Firefox, for example, has Show my windows and tabs from last time under General -> Home Page. Safari has SafariRestore. Explore other applications you use frequently  understand how they behave when opened.)