Ike.ninja

Netcraft has to date identified nearly 10,000 websites used in the distribution of the FluBot family of Android malware. As detailed in our previous articles on FluBot, these sites are unwittingly hosting a PHP script that acts as a proxy to a further backend server, allowing otherwise legitimate sites to deliver Android malware to victims. When visited by the intended victim, a “lure” is displayed that implores them to download and install the FluBot malware.

The most common lure themes are parcel delivery and voicemail messages, where the user is told to install the malicious app to track a parcel or listen to a voicemail message. One particularly interesting lure took advantage of FluBot’s infamy, by offering a fake “Android security update” that claimed to protect against the malware family. Users installing this “security update” would instead be infected with FluBot.

Most sites distributing FluBot malware also host legitimate content, suggesting they were compromised by the operators of this malware distribution network, without the knowledge of the site operator. While the use of unrelated domains makes the lures less convincing, as compared to domains specifically registered for fraud, it allows the malware distribution network to operate at a much larger scale.

These affected sites all have one factor in common: they run self-hosted WordPress instances. Netcraft believes the operators of this malware distribution network are actively exploiting well-known vulnerabilities in WordPress plugins and themes to upload malicious content onto insecure sites, joining a growing list of threat actors doing the same.