This malware campaign involves a fake Claude AI platform website distributing a backdoor named Beagle through malvertising. The infection chain leverages DLL sideloading by abusing a signed G DATA antivirus updater to load malicious payloads. Beagle backdoor supports eight commands including shell execution, file transfer, and directory listing, communicating with its C2 servers via AES encryption. Some samples date back to February 2026 and include variants deploying the AdaptixC2 framework. The attackers also impersonate domains of security vendors like Trellix, CrowdStrike, and SentinelOne. The infrastructure uses Cloudflare for malware distribution and Alibaba Cloud for command and control operations. There are no known exploits in the wild beyond this campaign, and no vendor advisories or patches have been identified.

The Beagle backdoor enables attackers to execute arbitrary shell commands, transfer files, and enumerate directories on compromised systems, potentially allowing extensive unauthorized control. The use of DLL sideloading with a signed antivirus updater may bypass some security controls. The campaign's use of malvertising and impersonation of trusted security vendors increases the likelihood of victim infection. However, no known widespread exploitation or additional threat actor attribution has been confirmed.

No official patch or remediation guidance is currently available for this threat. Defenders should block access to the identified malicious domains (claude-pro.com and license.claude-pro.com) and monitor for indicators of compromise related to DLL sideloading of the G DATA antivirus updater. Since this is a malware distribution campaign relying on social engineering, user awareness and blocking malvertising sources are recommended. Check vendor advisories regularly for updates on detection and remediation.