ACR Stealer: Two observed intrusion chains amid increased threat activity

From late April 2026 to mid-June 2026, Microsoft Defender Experts observed increased ACR Stealer activity across customer environments. These campaigns are successfully using ClickFix lures to steal browser credentials, authentication tokens, and sensitive documents from enterprise environments. The post ACR Stealer: Two observed intrusion chains amid increased threat activity appeared first on Microsoft Security Blog .

In this article Campaign 1: WebDAV-based ClickFix with Python loaders and blockchain C2 Campaign 2: MSHTA-initiated PowerShell chain with steganographic payload delivery Mitigation and protection guidance References Learn more From late April 2026 to mid-June 2026, Microsoft Defender Experts observed increased ACR Stealer activity across customer environments. These campaigns are successfully using ClickFix lures to steal browser credentials, authentication tokens, and sensitive documents from enterprise environments.

Successful compromise can expose browser credentials, session tokens, authentication artifacts, and sensitive enterprise data, potentially enabling account compromise, unauthorized access to cloud resources, and follow-on intrusion activity.