Threat Level: green Handler on Duty: Didier Stevens

SANS ISC: Some Android phones can be reset to factory default by clicking on links - SANS Internet Storm Center SANS ISC InfoSec Forums


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Some Android phones can be reset to factory default by clicking on links

Many mobile browsers do support "tel" urls, These URLs start with "tel:" instead of "http:", and can be used to create "call me" links on web pages. Usually, if a user clicks on one of these links, the phone will present a dialog, confirming if the user would like to "dial" the number.

However, some Android phones use special dial codes to access some of the phone's features. These codes are known as USSD codes (Unstructured Suplemental Service Data), and reasonably well documented. For example, if you type "*#06#" on your phone, it will show it's IMEI number before you hit "dial" (this works on most GSM phones, not just Android phones). Some Android phones add their own proprietary codes. For example, the Samsung Galaxy S3 phone has a code like this to perform a factory reset, which will delete all data on the phone, and once started, can not be canceled. As no "dial" action is required for these codes, just clicking the URL will execute the feature.

Here a quick test link that will show the IMEI: *#06# (iPhones will ask for confirmation first)

Demo video: http://www.youtube.com/watch?v=Q2-0B04HPhs

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Johannes B. Ullrich, Ph.D.
SANS Technology Institute
Twitter

I will be teaching next: Defending Web Applications Security Essentials - SANS Security West 2019

Johannes

3482 Posts
ISC Handler
Possible App to help the situation...

https://play.google.com/store/apps/details?id=org.mulliner.telstop
Sanesecurity

21 Posts
You can also use any other dialler than the stock one...

eg:

https://play.google.com/store/apps/details?id=kz.mek.DialerOne&hl=en

More info here:
http://dylanreeve.posterous.com/remote-ussd-attack
Sanesecurity

21 Posts
Imagine QR codes with this in public places. Certain folks will scan them just to see what comes up. Do something to make them more enticing, and cause more havoc. Oy.
Hal

50 Posts
There seems to be a temporary fix for this issue according to H-Online, already available on Google Play

http://www.h-online.com/security/news/item/App-protects-Samsung-smartphones-against-remote-wiping-1718531.html
Hal
3 Posts
http://en.wikipedia.org/wiki/Unstructured_Supplementary_Service_Data#Uses states that USSD may also be used to send money. Beware to scammers !

By the way, SS in USSD stands for "Suplementary Service", not "Suplemental Service" as stated in original article.
Anonymous

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