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ThreatLocker title card reading ThreatLocker MDR team intercepts Chimera C2 ClickFix attack on a dark blue background of flowing light lines.
Graphic: ThreatLocker, research title card for its Chimera C2 ClickFix intercept, Oct 21, 2026 (fair use).

Response

ThreatLocker Says a ClickFix Lure Ran the Victim's Clipboard as PowerShell, Pulled a ChimeraC2 Client From GitHub Into Memory and Gave Its Operators a Network Relay and a Command That Bricks Windows

ThreatLocker's managed detection and response team says it intercepted the Sept. 28 intrusion in a monitored environment. The .NET client loaded straight from GitHub, hid behind scheduled tasks named for WhatsApp Desktop and a WMI subscription, and answered to a panel whose login screen was only an overlay. The GitHub accounts, task names, addresses and commands to hunt.

Noah Park, ResponseNew York5 min read

NEW YORK - The victim was persuaded to paste a command, and the command read the rest of the clipboard and ran it. That was the opening of an intrusion that ThreatLocker's managed detection and response team says it identified and intercepted on Sept. 28, 2026, in a monitored environment, and described in research published Wednesday.

The ClickFix payload was a multi-line PowerShell script whose first line read the clipboard, skipped itself, rejoined the remaining lines and passed them to Invoke-Expression. Those lines ran a loop that fetched the next stage from GitHub: a file named update.dat in the repository MmAB96 under the account bluemarine999, with fallbacks at LirindAdams/bigfoxtrot999, which holds update-bs.dbf, and AmAA29/yankis29, since taken down. The file was base64-decoded, loaded reflectively into memory through .NET's System.Reflection.Assembly class, and an instance of ConsoleApp2.WsClient ran three methods, Connect, Register and RunLoop. If RunLoop exits, the loop goes back to GitHub, "persistently reaching out to GitHub and invoking the file downloaded until user logoff," ThreatLocker wrote.

ThreatLocker screenshot of the decoded ClickFix PowerShell loop, which downloads update.dat from raw GitHub URLs, falls back to a second repository, loads the assembly and calls Connect, Register and RunLoop.
Screenshot: ThreatLocker, the ClickFix payload that pulls the client from GitHub, Oct 21, 2026 (fair use).

ThreatLocker said Chimera has been attributed to a China-based group by MITRE and the broader intelligence community, but evidence its team saw "indicates that Russian-speaking threat actors are behind this panel." The apparently AI-assisted tooling does not match public reporting on Chimera, and the company said it cannot independently attribute the campaign to the previously documented group.

A WebSocket client with a relay

Update.dat carried .NET obfuscation and anti-ILDASM protections, which ThreatLocker stripped with the NETReactorSlayer tool. The client opens a WebSocket to its C2 server, 132.243.221.136 in this build, with a per-build token. It reports the machine name, user name, host name, current directory and whether it holds administrator rights, then waits for commands separated by ## characters: download, launch, plugin for .NET plugins, and info, which runs WMI queries for running processes, services, users, manufacturer, BIOS version, installed hotfixes and local IP addresses.

"The most impactful feature provided is a TCP relay," ThreatLocker wrote. The socks_connect, socks_data and socks_close commands let the operator reach locally hosted services and other machines through the victim's network identity, with multiple connections held open through one client. Despite the SOCKS label, the relay has none of the negotiation or authentication of a real SOCKS proxy.

A panel locked by an overlay

The C2 server's web login proved trivial. The login screen was an overlay, and hiding it in the browser exposed the full administrative panel already loaded into the page. Real authentication happens server side, so the exposed panel listed no victims; ThreatLocker fed an offline copy fabricated data to show its features. Each victim page has eight informational tabs, including a shell that switches between CMD and PowerShell with a file manager, and the panel runs a regular expression over installed software to flag crypto wallets. It looks for virtual machine tells, matches installed software against 70 antivirus providers and flags analysis tools, but leaves the decision to the operator.

ThreatLocker screenshot of the ChimeraC2 v3.0 operator panel populated with fabricated victim data, showing a client list and system information cards.
Screenshot: ThreatLocker, the ChimeraC2 panel populated with fabricated data by ThreatLocker, Oct 21, 2026 (fair use).

The panel can push two more payloads: wpv.exe, which nearby strings suggest steals browser passwords, and wcv.exe, which behaves like a cookie stealer. ThreatLocker said it found no instance where either was deployed. A second repository under bluemarine999, DbLogs37, held a clipboard clipper whose attacker wallets were all empty, which the company read as a sign that chain is still in development.

Persistence came two ways. Three scheduled tasks named for WhatsApp Desktop re-fetch the client from GitHub: WhatsAppDesktopScheduledServiceTask at SYSTEM level and WhatsAppDesktopServiceTask at administrator level trigger on boot and logon, and WhatsAppDesktopUserTask runs every four hours. Each carries a lengthy description claiming WhatsApp Desktop relies on it. A WMI event subscription in the root\subscription namespace runs the same command whenever sihost.exe starts, which happens on a graphical logon but not in sessions opened over SSH or WinRM.

brickBot

The last notable panel feature, brickBot, chains bcdedit, takeown, icacls, del and ren in one line to delete the current boot entry, delete winload.efi, rename hal.dll and ntoskrnl.exe and force an immediate restart. The panel's own confirmation prompt, visible in ThreatLocker's screenshot, warns that the computer will not boot again.

ThreatLocker screenshot of the panel source for the brickBot function, which builds a bcdedit, takeown, icacls, del and ren command line and sends it to the client.
Screenshot: ThreatLocker, the brickBot destruction routine in the ChimeraC2 panel source, Oct 21, 2026 (fair use).

The panel also lists clipboard stealers, keyloggers and RAM scrapers that no client ThreatLocker analyzed implements, which could point to other client builds or features still being written.

What responders should do now

  • Hunt PowerShell script block logs for Get-Clipboard feeding Invoke-Expression or IEX, and for loops that fetch from raw.githubusercontent.com paths under bluemarine999/MmAB96, bluemarine999/DbLogs37, LirindAdams/bigfoxtrot999 or AmAA29/yankis29.
  • Look for PowerShell loading a .NET assembly from memory and instantiating ConsoleApp2.WsClient.
  • Check Task Scheduler for WhatsAppDesktopScheduledServiceTask, WhatsAppDesktopServiceTask and WhatsAppDesktopUserTask, especially on machines without WhatsApp Desktop, and for task XML written to C:\Windows\Temp.
  • Enumerate WMI event subscriptions in root\subscription for filters keyed on sihost.exe.
  • Watch for C:\Users\Public\wallet_steal.ps1, wpv.exe or wcv.exe and a C:\Users\Public\Screenshots staging folder.
  • Sweep network logs for 132.243.221.136, 82.117.243.163 and 104.21.52.233 and the domains stake-app-au[.]org, domain-privacy[.]group and tergenerator[.]com. ThreatLocker's report lists SHA-256 hashes for the four GitHub-hosted files.
  • Treat bcdedit /delete, takeown or icacls against winload.efi, or renames of hal.dll or ntoskrnl.exe, as a destructive event that calls for immediate isolation.
  • A machine where these tasks or the WMI subscription are found should be treated as hands-on-keyboard compromised, because the relay gives the operator a path to everything that host can reach.

Sources:


Noah Park covers incident response, containment, and blue-team operations for SOCtember from New York.

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