What are HummingWhale malware's new ad fraud features?

The HummingBad Android malware, which affected about 10 million devices with its ad fraud activities, resurfaced as HummingWhale, and was being distributed through 20 apps in the Google Play Store. What are the new features of HummingWhale, and how do they work?

As malware and ad developers begin to adopt good ideas and learn from each other to advance their goals, the distinction between malware and adware continues to be blurred. Mobile malware developers seem to be rapidly adopting functionality for generating revenue from their malware.

Check Point researchers discovered a new variant of the HummingBad mobile malware, named HummingWhale, which uses virtual machines as part of its effort to evade antifraud detection in order to generate ad revenue. The HummingWhale malware also tries to raise its reputation in the Google Play Store by using fraudulent ratings and comments, much like the Gooligan malware. It was also found on third-party app stores.

Once the HummingWhale malware is on the endpoint, it downloads a dropper used to further download DroidPlugin. Fake ads and apps are displayed to the user, and when the user attempts to close out the ads, fraudulent apps are uploaded onto the virtual machine. This creates a fake referrer ID, which the HummingWhale malware uses to generate revenue. By using this technique, it can also bypass security checks on the endpoint.

An app with the ability to download external content seems like it could be at high risk, and would be something Google would only cautiously allow, as it is difficult to determine all of the actions an executable might take.

The standard security advice is to only download apps from trusted app stores and to look for highly rated apps, but as HummingWhale demonstrates, this may be insufficient to adequately protect a device. Users should install a third-party security tool, as well.