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10
Apr

Compress any file into a Tweet?!

This morning I launched HAshrink.com, an online tool for reducing any file to a tiny, almost impossible size.


Screen Shot 2012 04 09 at 12 50 53 PM

I launched a fun website for it, as a portmanteau of “Hash” and “Shrink”.

The theory behind it was one I first started playing with in 2008, which is the idea of creating every possible iteration of a file, to find all the hash-collisions.

You’d then reject any candidates that didn’t fit certain qualifications. For instance, you might reject any file that isn’t a valid MP3, or any file that doesn’t match a perceptual hash
After all the filters, you’d indicate which hash-collision generated the correct version of you file.

I wrote up two versions to play with the idea, and see what it might look like.



Writing it was a lot of fun, and I got more practice using multi-processor code in Python.
Unfortunately, it’s entirely impractical, at least without Quantum Computers.

The problem is, even a fast machine using the GPU can only do 400K hash collisions per second.

At this rate, it would take more time to re-create the file, than has so-far elapsed in the universe.
That’s a bit slow 😉

In any event, I figured it’d be fun to make up a website for the project, and put a demo online, which calculates how-long your file would take to return.

After a bit of playing and a cheap template from ThemeForest, I put together some images for it.

The logo was a lot of fun, trying to emphasize the dual-nature of the name.

I also had fun trying to make images which ‘pop’I hate this word, and get practice using some flash tools to cycle between them.

HAshrink.com was born.

9
Apr

Identity Based Trojans

Alt. Linkbait title- “Is your iPhone Spying on you? [1]

SpyMode

Apple is famous for their “Walled Garden” approach to the iPhone and iPad.
No software ships on the phone without their expressed approval.
The downside of this approach is that Apple has control over what you are allowed to use- They can block eReaders, Podcast software, and Torrent client, and there’s not much you can do about it.

In exchange, the protect you from having to worry about Trojans, Viruses, and other Malware.

The problem is, there’s a whole class of Malware that Apple hasn’t (and really can’t) do much to protect against at all.

If you’re dedicated to stealing info from someone’s cellphone, cleverly written apps are a good way to get started.

Your Apps know who you are

Every app you install has various ways of knowing who you are.

It can use various hardware unique identifiers to compare against other databases, it can check your address book, and see who you say you are, and although Apple is starting to restrict these, there are still alternatives for tracking you across multiple applications.
Apps can pull your phone’s name from APIs.
Using undocumented APIs, apps can directly even pull your email address without explicit permission.

The app could also just load the Phone Number directly. This method has been Exploited Before.

Or, if everything else fails, it can ask you to sign up for an account, and give it an email and password. Almost everyone uses the same email address for all their programs, so it ties them fair uniquely.

Your app can spy on you

One the Application knows you you are, it could begin selectively spying on you.
Once the App has identified that you are a target worth spying on, it has several options.

It could pull pictures from your camera roll.
It could take pictures of you, using either the frontside or backside camera, without showing you the viewfinder.
The phone could record audio of you, and upload it all to the badguy headquarters.

Wouldn’t Apple block the App?

If they found out about it, yes.
Once the fact that your app was doing that became public, Apple would almost certainly pull the App.
The problem is, if your careful, Apple is unlikely to know.

Appstore Reviews consist mainly of manually operating/examining the app, and automatically looking though the executable for internal-only APIs.
Apple doesn’t receive or review the source-code to your application, and can’t watch every execution path.
This is what allowed other applications to Slip through the review process.

If you are discreet in what you do- For example, only record video of a few select targets, it seems likely you’d be able to get away with this for quite some time.

What can I do?

Luckily, Apple is taking steps to make this exploit more difficult.
They’re making it more difficult to determine who you are, or to access the Address Book without your permission.
Down the line, they may decide to require a prompt before accessing the Camera or Microphone.

Until then, there’s not much you can do.
Unlike on the Macbooks, there’s no green light next to the camera when it is recording.
Even the NextStations had a hardware light when they were recording Audio

The best advice I have, if you’re paranoid, is
1) Don’t Jailbreak. This only adds other attack vectors.
2) Under Settings, General, Restrictions, you can disable the Camera.
Photo

This will stop applications from accessing it, but will also be rather inconvenient, if you ever do want to take a picture.
Perhaps, if you’re worried, you should carry a point-and-shoot.

Is this likely

No. Unless you’re famous, it seems possible, but unlikely, for you to be targeted for a customized attack.

Footnotes:
[1] – No.



Portions of the title image copied from renaissancechambara.
Others from iStockPhoto.