What Is Millenium RAT?
A complete technical explanation of the Windows remote-access trojan, its history, architecture, and why it matters for defenders.
What is Millenium RAT? Millenium RAT is a Windows remote-access trojan and information-stealing malware family first publicly analyzed by CYFIRMA in November 2023. It enables unauthorized remote control, credential and browser-data theft, keylogging, screenshots and surveillance. Newer 4.x versions were rewritten in native C++ and use the Telegram Bot API for command-and-control. Group-IB reported more than 62,000 compromised endpoints across 160+ countries.
A short definition
Millenium RAT (also searched as Millennium RAT) is a Windows remote-access trojan (RAT) combined with information-stealing functionality. A RAT gives an attacker unauthorized remote control of a compromised machine; an infostealer harvests sensitive data such as browser credentials, cookies, and cryptocurrency wallet information. Millenium RAT performs both roles.
CYFIRMA published the first major public analysis on November 3, 2023, focusing on version 2.4 — a Win32 executable developed in .NET. Broadcom/Symantec published protection information the same month. In June 2026, Group-IB published a major analysis of version 4.x, revealing a substantial rewrite in native C++ and a global campaign of tens of thousands of compromised endpoints.
Why it matters
Millenium RAT matters for three reasons: scale, accessibility, and architectural evolution. Group-IB telemetry identified 62,289 compromised endpoints across 160+ countries. The malware is sold under a low-cost Malware-as-a-Service model that lowers the skill and financial barriers to cybercrime. And the move from .NET to native C++ changes how defenders must analyze and detect it.
Defensive scope of this resource
This portal documents Millenium RAT purely for defensive purposes. It does not host malware binaries, source code, RAT builders, or weaponization instructions. All indicators are defanged. Where capabilities are described, the focus is their function and security impact — not an operator manual.
- 01Type: Remote Access Trojan / Infostealer
- 02Platform: Microsoft Windows
- 03First analyzed: November 3, 2023 (CYFIRMA, v2.4)
- 04Rewritten: native C++ in v4.x (Group-IB, 2026)
- 05C2: Telegram Bot API (abused legitimate platform)
- 06Scale: 62,289 endpoints / 160+ countries (Group-IB)
- 07Developer alias: ShinyEnigma
- 08Operational cluster: Y2K Operators
How Millenium RAT operates
- ▸Millenium RAT is a Windows RAT + infostealer, not a zero-day exploitation framework.
- ▸It abuses the legitimate Telegram Bot API for command-and-control and exfiltration.
- ▸The 4.x branch is a native C++ rewrite of the earlier .NET 2.x family.
- ▸Group-IB reported 62,289 endpoints across 160+ countries; counts reflect telemetry, not every infection.
- ▸Marketed as Malware-as-a-Service at low cost (~US$50 first month).
Technical Analysis
Telegram C2
Capabilities
