Mstsc.EXE Execution With Local RDP File

Status: test
Severity: low
Log source: category process_creation, product windows
Author: Nasreddine Bencherchali (Nextron Systems), Christopher Peacock @securepeacock
Source: github.com/SigmaHQ/sigma

Detects potential RDP connection via Mstsc using a local ".rdp" file

Known false positives

Likely with legitimate usage of ".rdp" files

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	`T1219.002` Remote Access Tools: Remote Desktop Software

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

title: Mstsc.EXE Execution With Local RDP File
id: 5fdce3ac-e7f9-4ecd-a3aa-a4d78ebbf0af
status: test
description: Detects potential RDP connection via Mstsc using a local ".rdp" file
references:
    - https://www.blackhillsinfosec.com/rogue-rdp-revisiting-initial-access-methods/
    - https://web.archive.org/web/20230726144748/https://blog.thickmints.dev/mintsights/detecting-rogue-rdp/
author: Nasreddine Bencherchali (Nextron Systems), Christopher Peacock @securepeacock
date: 2023-04-18
modified: 2023-04-30
tags:
    - attack.command-and-control
    - attack.t1219.002
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\mstsc.exe'
        - OriginalFileName: 'mstsc.exe'
    selection_cli:
        CommandLine|endswith:
            - '.rdp'
            - '.rdp"'
    filter_optional_wsl:
        ParentImage: 'C:\Windows\System32\lxss\wslhost.exe'
        CommandLine|contains: 'C:\ProgramData\Microsoft\WSL\wslg.rdp'
    condition: all of selection_* and not 1 of filter_optional_*
falsepositives:
    - Likely with legitimate usage of ".rdp" files
level: low

Stages and Predicates

Stage 0: `condition`

all of selection_* and not 1 of filter_optional_*

Stage 1: `selection_img`

selection_img:
    - Image|endswith: '\mstsc.exe'
    - OriginalFileName: 'mstsc.exe'

Stage 2: `selection_cli`

selection_cli:
    CommandLine|endswith:
        - '.rdp'
        - '.rdp"'

Stage 3: `not filter_optional_wsl`

filter_optional_wsl:
    ParentImage: 'C:\Windows\System32\lxss\wslhost.exe'
    CommandLine|contains: 'C:\ProgramData\Microsoft\WSL\wslg.rdp'

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`CommandLine`	match	`C:\ProgramData\Microsoft\WSL\wslg.rdp`	`excludes:CommandLine` `field:"CommandLine" value:"C:\ProgramData\Microsoft\WSL\wslg.rdp"`
`ParentImage`	eq	`C:\Windows\System32\lxss\wslhost.exe`	`excludes:ParentImage` `field:"ParentImage" value:"C:\Windows\System32\lxss\wslhost.exe"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	ends_with	`.rdp` corpus 2 (sigma 2) `.rdp"` corpus 2 (sigma 2)	`field:"CommandLine" kind:ends_with`
`Image`	ends_with	`\mstsc.exe` corpus 6 (sigma 6)	`field:"Image" kind:ends_with value:"\mstsc.exe"`
`OriginalFileName`	eq	`mstsc.exe` corpus 5 (sigma 4, elastic 1)	`field:"OriginalFileName" kind:eq value:"mstsc.exe"`

Mstsc.EXE Execution With Local RDP File

Known false positives

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection_img

Stage 2: selection_cli

Stage 3: not filter_optional_wsl

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_cli`

Stage 3: `not filter_optional_wsl`