Malicious IIS Extensions Gaining Popularity Among Cyber Criminals for Persistent Access
Jul 27, 2022
Threat actors are increasingly abusing Internet Information Services ( IIS ) extensions to backdoor servers as a means of establishing a "durable persistence mechanism." That's according to a new warning from the Microsoft 365 Defender Research Team, which said that "IIS backdoors are also harder to detect since they mostly reside in the same directories as legitimate modules used by target applications, and they follow the same code structure as clean modules." Attack chains taking this approach commence with weaponizing a critical vulnerability in the hosted application for initial access, using this foothold to drop a script web shell as the first stage payload. This web shell then becomes the conduit for installing a rogue IIS module to provide highly covert and persistent access to the server, in addition to monitoring incoming and outgoing requests as well as running remote commands. Indeed, earlier this month, Kaspersky researchers disclosed a cam...
