How to check if your Android phone is vulnerable to the USSD security flaw

Is your Android phone at risk to a USSD security flaw? Here's how to find out

The Samsung Galaxy S III is one Android phone that is susceptible to the USSD security flaw.

The Samsung Galaxy S III is one Android phone that is susceptible to the USSD security flaw.

A security flaw has been discovered on various Android smartphones that allows a USSD code to perform a factory reset without any confirmation prompt. Is your Android phone at risk? Here's how to find out.

The USSD flaw was highlighted overnight at a Security Conference in Buenos Aires, Argentina by Ravi Borganokar, a researcher in the telecommunications department at the Technical University of Berlin. It was first said to occur only on various Samsung smartphones running the TouchWIZ UI overlay, but it has since been discovered that the problem can affect various other Android phones, too.

The USSD codes themselves aren't a problem, but on some Android phones these can be executed without a confirmation prompt. Some of these codes, typed into the phones keypad, are harmless (such as the one used to display a phone's IMEI number) but other codes can factory reset the phone. USSD codes typically start with an asterisk (*) followed by numbers and almost always end with a hash (#).

On Android phones that don't require a confirmation prompt, a factory reset USSD code can be dialled automatically by the phone. While it's almost impossible to dial the code into the dialler accidentally, this code could be embedded into a URL link, a QR code, or an SMS by a hacker. This would mean you phone would be factory reset as soon as you opened the malicious link.

To check if your Android phone is vulnerable, follow these steps:

1. Visit this link through your phone's Web browser. Don't worry, it's a test page so it's not going to reset your phone!

2. If your phone's dialler pops up and shows a number, your phone isn't affected and there's no need to worry. This is shown below on a Sony Xperia go:

However, if your phones dialler pops up and immediately displays a pop up menu with your IMEI number, your phone is vulnerable to this security flaw. This is displayed below on a Samsung Galaxy S III:

To fix this security flaw until your carrier or manufacturer issues a patch for the problem, you can download an app called TelStop. You can find it in the Google Play Store here.

1. Install TelStop from the Google Play Store. You should see this screen when you open it.

2. Close the app and now visit this link again through your phone's Web browser. You should now see a prompt that asks if you'd like to complete this action using your stock dialler or TelStop, as shown below:

3. To see the link, select TelStop. You will then receive a warning that this is likely a malicious code, as shown below:

From now on, if you click a link on your phone or scan a QR code and you see the above screen, it is likely to be hidden code that could wipe your phone.

Is your Android phone affected by the USSD security flaw? Run the tests above and let us know in the comments below.

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.
Ross Catanzariti

Ross Catanzariti

PC World
Show Comments

Cool Tech

Toys for Boys

Family Friendly

Stocking Stuffer

SmartLens - Clip on Phone Camera Lens Set of 3

Learn more >

Christmas Gift Guide

Click for more ›

Brand Post

Bitdefender 2019

This Holiday Season, protect yourself and your loved ones with the best. Buy now for Holiday Savings!

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Aysha Strobbe

Microsoft Office 365/HP Spectre x360

Microsoft Office continues to make a student’s life that little bit easier by offering reliable, easy to use, time-saving functionality, while continuing to develop new features that further enhance what is already a formidable collection of applications

Michael Hargreaves

Microsoft Office 365/Dell XPS 15 2-in-1

I’d recommend a Dell XPS 15 2-in-1 and the new Windows 10 to anyone who needs to get serious work done (before you kick back on your couch with your favourite Netflix show.)

Maryellen Rose George

Brother PT-P750W

It’s useful for office tasks as well as pragmatic labelling of equipment and storage – just don’t get too excited and label everything in sight!

Cathy Giles

Brother MFC-L8900CDW

The Brother MFC-L8900CDW is an absolute stand out. I struggle to fault it.

Luke Hill

MSI GT75 TITAN

I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it.

Emily Tyson

MSI GE63 Raider

If you’re looking to invest in your next work horse laptop for work or home use, you can’t go wrong with the MSI GE63.

Featured Content

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?