Mstsc.EXE Execution From Uncommon Parent

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

Detects potential RDP connection via Mstsc using a local ".rdp" file located in suspicious locations.

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `all of selection_parent`

or:
ParentImage|endswith: '\CCleanerBrowser.exe'
ParentImage|endswith: '\brave.exe'
ParentImage|endswith: '\chrome.exe'
ParentImage|endswith: '\chromium.exe'
ParentImage|endswith: '\firefox.exe'
ParentImage|endswith: '\iexplore.exe'
ParentImage|endswith: '\microsoftedge.exe'
ParentImage|endswith: '\msedge.exe'
ParentImage|endswith: '\opera.exe'
ParentImage|endswith: '\outlook.exe'
ParentImage|endswith: '\vivaldi.exe'
ParentImage|endswith: '\whale.exe'

Stage 2: `all of selection_img`

or:
Image|endswith: '\mstsc.exe'
OriginalFileName: mstsc.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
`Image`	ends_with	`\mstsc.exe` corpus 5 (sigma 5)
`OriginalFileName`	eq	`mstsc.exe` corpus 4 (sigma 4)
`ParentImage`	ends_with	`\CCleanerBrowser.exe` `\brave.exe` corpus 2 (sigma 2) `\chrome.exe` corpus 4 (sigma 4) `\chromium.exe` `\firefox.exe` corpus 3 (sigma 3) `\iexplore.exe` corpus 2 (sigma 2) `\microsoftedge.exe` corpus 2 (sigma 2) `\msedge.exe` corpus 3 (sigma 3) `\opera.exe` `\outlook.exe` corpus 4 (sigma 4) `\vivaldi.exe` corpus 2 (sigma 2) `\whale.exe`