Avira USSD Exploit Blocker is a free security application proposed by Avira, available on Google Play, specially developped for Android smartphones (as from version 4.0). It allows users to protect their devices against USSD attacks (Unstructured Supplementary Service Data).
The USSD functionality is a data transmission standard that make use of the GSM channels - it is normally used for monitoring the balance available on smartphones (e.g remaining talk-time) and other information related to pre-paid GSM services and it actually represents an attack vector on Android platform.
A vulnerability allowing hackers to take control of smarpthones (remotely).
"Clear data remotely and make calls to premium rate numbers"
As explained by Avira, the risks are as follow:
The USSD vulnerability operates using special dialing codes, e.g * # 06 #to display the IMEI number of a phone. The smartphone can be manipulated remotely by SMS, NFC or via a malicious web link, allowing the hacker to lock the phone's SIM card or reset the smartphone, thereby erasing all data.
Hackers can also use a special code, all calls can be redirected to a premium rate number.
The application proposed by Avira blocks USSD codes can can be used to tamper the SIM card of the device.