Another interesting aspect of this new spam campaign is that it targets multiple platforms. The links spammed in the rogue emails lead to some websites that check the User-Agent headers sent by users' browsers to determine their OSes. If a visiting user runs a Windows browser the website will serve a malicious .zip file containing Windows malware, but if they're using an Android browser it will serve the malicious Android APK.
"The first time we saw a platform-aware spam campaign that also involves Android was in March this year, when spamvertised links would redirect users to either infected APKs or to a Blackhole exploit kit," Botezatu said. "This way, every single potential victim is carefully profiled for flaws and redirected to the appropriate infection mechanism. This technique could either hint that cyber-criminals who deal with Windows malware are expanding their business to other platforms, or that they are actually leasing their infrastructure to cyber-criminals with a particular focus on Android."
"More and more threats are multi-browser and multi-OS enabled, ensuring maximum coverage on user endpoints and maximum distribution," Steer said.
Like Android threats distributed from third-party app stores, the Android scareware distributed through this spam campaign can only affect devices configured to allow the installation of apps from sources other than Google Play. This is a setting that comes disabled by default in Android, but many users turn it on, primarily because they want to install legitimate apps that are not available on Google Play or because they don't have Google Play access.
"I'd say that there are plenty of users out there who allow installation of applications outside the official channel," Botezatu said. "Although I can't speculate on numbers, there is a huge pool of Android adopters in Asia, for instance, who can't fully take advantage of Google Play, so they have to rely on third-party markets to buy apps."
Most users are not security conscious and are unaware of the implications of turning this feature on, Steer said.