Threat actors associated with the DragonForce ransomware have been observed using a custom Go-based remote access trojan (RAT) called Backdoor.Turn to conceal command-and-control (C2) traffic inside Microsoft Teams relay infrastructure. According to findings from Broadcom-owned Symantec and Carbon Black, the backdoor was deployed against a major U.S. services firm. The name of the company was not disclosed. "Backdoor.Turn obtains an anonymous Teams visitor token from Microsoft’s Skype-backed identity services, uses a legitimate Microsoft TURN relay to set up the connection, and then runs a QUIC session to the attacker’s real command-and-control (C2) server," the Threat Hunter Team said in a report shared with The Hacker News. "To network defenders, the only traffic they could see was…