VMToolsd Suspicious Child Process

Severity: high
Author: bohops, Bhabesh Raj
Source: upstream

Detects suspicious child process creations of VMware Tools process which may indicate persistence setup

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059` Command and Scripting Interpreter

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `all of selection_parent`

ParentImage|endswith: '\vmtoolsd.exe'

Stage 2: `all of selection_img`

or:
Image|endswith: '\cmd.exe'
Image|endswith: '\cscript.exe'
Image|endswith: '\mshta.exe'
Image|endswith: '\powershell.exe'
Image|endswith: '\pwsh.exe'
Image|endswith: '\regsvr32.exe'
Image|endswith: '\rundll32.exe'
Image|endswith: '\wscript.exe'
OriginalFileName: Cmd.Exe
OriginalFileName: MSHTA.EXE
OriginalFileName: PowerShell.EXE
OriginalFileName: REGSVR32.EXE
OriginalFileName: RUNDLL32.EXE
OriginalFileName: cscript.exe
OriginalFileName: pwsh.dll
OriginalFileName: wscript.exe

Stage 3: `not 1 of filter_main_*`

or:
or:
CommandLine|contains: '\VMware\VMware Tools\poweroff-vm-default.bat'
CommandLine|contains: '\VMware\VMware Tools\poweron-vm-default.bat'
CommandLine|contains: '\VMware\VMware Tools\resume-vm-default.bat'
CommandLine|contains: '\VMware\VMware Tools\suspend-vm-default.bat'
Image|endswith: '\cmd.exe'
CommandLine: ''
Image|endswith: '\cmd.exe'
CommandLine: null
Image|endswith: '\cmd.exe'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`CommandLine`	match	`\VMware\VMware Tools\poweroff-vm-default.bat` `\VMware\VMware Tools\poweron-vm-default.bat` `\VMware\VMware Tools\resume-vm-default.bat` `\VMware\VMware Tools\suspend-vm-default.bat`
`Image`	ends_with	`\cmd.exe` corpus 92 (sigma 92) `\cscript.exe` corpus 64 (sigma 64) `\mshta.exe` corpus 57 (sigma 57) `\powershell.exe` corpus 143 (sigma 143) `\pwsh.exe` corpus 140 (sigma 140) `\regsvr32.exe` corpus 57 (sigma 57) `\rundll32.exe` corpus 76 (sigma 76) `\wscript.exe` corpus 64 (sigma 64)
`OriginalFileName`	eq	`Cmd.Exe` corpus 32 (sigma 30, splunk 2) `MSHTA.EXE` corpus 7 (sigma 7) `PowerShell.EXE` corpus 64 (sigma 60, splunk 4) `REGSVR32.EXE` corpus 10 (sigma 10) `RUNDLL32.EXE` corpus 28 (sigma 25, splunk 3) `cscript.exe` corpus 15 (sigma 15) `pwsh.dll` corpus 72 (sigma 68, splunk 4) `wscript.exe` corpus 15 (sigma 15)
`ParentImage`	ends_with	`\vmtoolsd.exe`