Bitdefender Labs has released Bitdefender USSD Wipe Stopper to protect Android users from a USSD attack. The app detects when a USSD code is accessed and notifies the user heâ€™s about to trigger a potentially harmful USSD code.
The Android dialer this week was found vulnerable to a remote wipe attack by means of passing specialized strings of characters with a certain prefix to the phoneâ€™s dialer. The attack was demonstrated via a website link containing the USSD remote wipe code for a Samsung Galaxy S3, which was interpreted as a special dialer string.
By using the â€œtelâ€ URL prefix to hyperlink to phone numbers, Android users clicking the link trigger the phone dialer to call the USSD code. The automatic process of initiating the â€œrestore to factory settingsâ€ or displaying the IMEI, requires no user intervention whatsoever.
Considering the attackâ€™s trivial nature, using a browserâ€™s User Agent or an iFrame to detect each Android device and serve a specific USSD code could easily be implemented even by poorly skilled coders.
The USSD attack could be delivered via a plethora of methods which include WAP Push SMS, QR Codes and even NFC. With such a broad attack vector, users should exercise extreme caution when hitting links or scanning QR codes.
Other Samsung devices have since proven prone to the same attack. Samsung said it patched the vulnerability earlier this year but not all devices received the update. Although no weaponised version of the attack was yet found in the wild, the seriousness of the vulnerability cannot be ignored.
Other Android builds ranging from Android 2.3 to Android 4.0.3 were found as vulnerable to the attack as the proof-of-concept Samsung Galaxy S3, potentially placing hundreds of thousands of users at risk.
The Android tool released by Bitdefender Labs enables users to check if their device is vulnerable or not to the USSD attack.