September 21, 2021

Threat actors are compromising Microsoft Windows web server software, Internet Information Services (IIS) to add expired certificate notification pages that prompt visitors to download a malicious fake installer.

According to security experts at Malwarebytes Threat Intelligence, the malware in question is installed via a fake update installer called VirusTotal, signed with a Digicert certificate.

Once the payload identified as TVRAT is dropped on infected systems, the malware silently installs and starts an instance of TeamViewer remote control software.

It then accesses a command-and-control server that warns attackers of the possibility of remotely taking complete control of the newly compromised computer.

The vulnerability has not been exploited in the wild, although the method by which attackers compromise IIS servers is still unknown.

It is worth noting that most potential targets are safe from attack since most home users have already updated their Windows 10 and most companies do not use the latest versions of Windows Server.

For more information, read the original story in Bleeping Computer.