Description

A newly discovered cyber-espionage campaign by the Russia-aligned APT group Water Gamayun demonstrates how the threat actor leverages a zero-day vulnerability in Windows MMC (CVE-2025-26633, "MSC EvilTwin") to gain entry into high-value networks. It starts with an innocent web search but quickly escalates as the attackers leverage this zero-day flaw to inject malicious code directly into mmc.exe, a trusted Windows administrative binary. The attackers abuse legitimate TaskPad snap-in commands to invoke and deliver stealthy PowerShell stages that drop their payloads while bypassing traditional security controls. Zscaler researchers discovered that the infection chain has its anchor in a calculated social-engineering funnel. Victims searching for BELAY, a staffing solutions provider, are silently redirected from a compromised legitimate site to a deceptive lookalike domain, belaysolutions[.]link. There, users encounter a file named Hiring_assistant.pdf.rar -a double-extension archive crafted to appear as an innocuous PDF. When opened, the MSC EvilTwin exploit is activated, which initiates a surreptitious PowerShell script that retrieves ancillary tools such as UnRAR.exe and a password-protected archive containing the next malware stage. This multi-layered delivery mechanism serves to obscure the true nature of the attack until the final payload is executed. The infection culminates in the installation of ItunesC.exe, a loader believed to be associated with malware families previously used by Water Gamayun, such as SilentPrism, DarkWisp, or the Rhadamanthys stealer—though confirmation was limited due to inactive command-and-control infrastructure. Zscaler attributes the campaign to Water Gamayun with high confidence, citing their history of supply-chain exploitation, zero-day usage, and advanced obfuscation techniques. The group's objectives seem to revolve around strategic intelligence collection, credential harvesting, and continued lateral movement within targeted organizations. This campaign underlines not only the sophistication of Water Gamayun but also the operational discipline, as well as the critical need for organizations to harden defenses around trusted system binaries and emerging zero-day vectors.?