Suspicious Provlaunch.EXE Child Process

Severity: high
Author: Nasreddine Bencherchali (Nextron Systems)
Source: upstream

Detects suspicious child processes of "provlaunch.exe" which might indicate potential abuse to proxy execution.

MITRE ATT&CK coverage

Tactic	Techniques
Defense Evasion	`T1218` System Binary Proxy Execution

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation
Security-Auditing	4688	A new process has been created.

Stages and Predicates

Stage 1: `all of selection_parent`

ParentImage|endswith: '\provlaunch.exe'

Stage 2: `all of selection_child`

or:
Image|endswith: '\calc.exe'
Image|endswith: '\cmd.exe'
Image|endswith: '\cscript.exe'
Image|endswith: '\mshta.exe'
Image|endswith: '\notepad.exe'
Image|endswith: '\powershell.exe'
Image|endswith: '\pwsh.exe'
Image|endswith: '\regsvr32.exe'
Image|endswith: '\rundll32.exe'
Image|endswith: '\wscript.exe'
Image|contains: ':\PerfLogs\'
Image|contains: ':\Temp\'
Image|contains: ':\Users\Public\'
Image|contains: '\AppData\Temp\'
Image|contains: '\Windows\System32\Tasks\'
Image|contains: '\Windows\Tasks\'
Image|contains: '\Windows\Temp\'

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
`Image`	ends_with	`\calc.exe` corpus 13 (sigma 13) `\cmd.exe` corpus 92 (sigma 92) `\cscript.exe` corpus 64 (sigma 64) `\mshta.exe` corpus 57 (sigma 57) `\notepad.exe` corpus 11 (sigma 11) `\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)
`Image`	match	`:\PerfLogs\` corpus 4 (sigma 4) `:\Temp\` corpus 12 (sigma 12) `:\Users\Public\` corpus 14 (sigma 14) `\AppData\Temp\` corpus 3 (sigma 3) `\Windows\System32\Tasks\` corpus 4 (sigma 4) `\Windows\Tasks\` corpus 4 (sigma 4) `\Windows\Temp\` corpus 7 (sigma 7)
`ParentImage`	ends_with	`\provlaunch.exe` corpus 2 (sigma 2)

Neighbors

Equivalent rules

1 other rule has the same matching logic as this one. Useful for cross-vendor comparison or picking the variant your stack supports. See eq_0002.