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MostereRAT Malware Campaign Targets Japanese Windows Users

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📰 2 unique sources, 2 articles

Summary

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A new malware campaign involving MostereRAT, a banking malware-turned-remote access Trojan (RAT), has been identified. This campaign uses sophisticated evasion techniques, including the use of an obscure programming language, disabling of security tools, and mutual TLS (mTLS) for command-and-control communications to maintain long-term access to compromised systems. The malware targets Microsoft Windows users in Japan, deploying through phishing emails and weaponized Word documents. MostereRAT's capabilities include persistence, privilege escalation, AV evasion, and remote access tool deployment. The campaign highlights the importance of removing local administrator privileges and blocking unapproved remote access tools. The malware's design reflects long-term, strategic, and flexible objectives, with capabilities to extend functionality, deploy additional payloads, and apply evasion techniques. These features point to an intent to maintain persistent control over compromised systems, maximize the utility of victim resources, and retain ongoing access to valuable data.

Timeline

  1. 08.09.2025 23:49 📰 2 articles · ⏱ 7d ago

    MostereRAT Malware Campaign Discovered

    The campaign incorporates advanced evasion techniques, including the use of an Easy Programming Language (EPL) to develop a staged payload, mutual TLS (mTLS) for securing command-and-control communications, and disabling security tools to prevent alert triggers. The malware can deploy additional payloads using various methods and install remote access tools like AnyDesk, TigerVNC, and TightVNC. It can block network traffic associated with a hard-coded list of security programs and monitor foreground window activity associated with Qianniu - Alibaba's Seller Tool. The malware can send heartbeat signals to an external server, process commands issued by the server, facilitate RDP logins, and create hidden administrator accounts.

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Information Snippets

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