Virus-hunter Symantec says the Android master key vulnerability is being exploited in China, where half-a-dozen apps have showed up with malicious content hiding behind a supposedly-safe crypto key.
The simple, straightforward and utterly stupid vulnerability arises because, as Bluebox Security demonstrated recently, someone with evil intent and hardly any expertise can pack an Android APK package (a Zip file under another extension) with files carrying the same name as those in the archive.
As noted by El Reg here, Android's crypto system verifies the first version of any repeated file in an APK – but the installer picks up the last version. On 22 July, BitDefender identified a number of apps popping up on the Google Play store.
Now, Symantec has joined the party, identifying apps in China that have been exploited with the vulnerability to plant malicious code. There's two apps designed for doctor-finding, a news app, an arcade game, and a betting/lottery app.
The good news for Androiders outside the Great Firewall is that all the malicious apps were being distributed on Chinese Android marketplaces rather than Google Play.
Symantec's post states that the same attacker embedded code in all the compromised apps. The aim of the attack is to remotely control devices, steal data such as IMEI and phone numbers, send premium SMS messages, and on rooted devices, disable some Chinese mobile security apps. ®