The host at this IP address is running a malware botnet controller which is being used to control infected computers (bots) around the globe using a trojan horse.
Kovter botnet controller located at 91.213.50.136 on port 80 (using HTTP GET):
hXXp://91.213.50.136/QgIc/gate.php
Referencing malware binaries (MD5 hash):
bfdf6b8b7c1edd61333b1659222c3457 — AV detection: 10 / 68 (14.71)