Security researchers have tracked a malware distribution campaign spreading the FinFisher spyware — also known as FinSpy — to the infrastructure of Internet Service Providers (ISPs) in at least two countries.
Researchers suspect that ISPs used their ability to control user trafic and redirect users attempting to download certain software to a different link offering the same software, but laced with the FinFisher spyware.
The list of malware-infected applications delivered this way includes products such as WhatsApp, Skype, Avast, WinRAR, VLC Player and others.
ESET, the cyber-security company that detected these download link switcheroos — says it cannot name the countries where it identified the ISP-level intervention "so as not to put anyone in danger."
Attacks most certainly carried out at ISP level
These types of attacks, when a third-party intervenes in a victim's web traffic and switches content, are called Man-in-the-Middle (MitM) attacks.
Researchers say they reached the conclusion that ISPs were carrying out the MitM attacks because recent detections with FinFisher spyware in the two affected countries were spread over a wide geographical area and users could have not been the victims of a MitM attack carried out via local networks, such as WiFi hotspots.
The only technically feasible way to alter the download links for so many apps and so many users across a broad geographical area, in the same way, was with the help of an ISP-level MitM.
Furthermore,
documents leaked by WikiLeaks show that the company that sells the FinFisher spyware also provides a package that can be installed at the ISP level.