Convert indexed Sigma rules into analyst-ready detections.

title: Suspicious Electron Application Child Processes
id: f26eb764-fd89-464b-85e2-dc4a8e6e77b8
related:
    - id: 378a05d8-963c-46c9-bcce-13c7657eac99
      type: similar
status: test
description: |
    Detects suspicious child processes of electron apps (teams, discord, slack, etc.). This could be a potential sign of ".asar" file tampering (See reference section for more information) or binary execution proxy through specific CLI arguments (see related rule)
references:
    - https://taggart-tech.com/quasar-electron/
    - https://github.com/mttaggart/quasar
    - https://positive.security/blog/ms-officecmd-rce
    - https://lolbas-project.github.io/lolbas/Binaries/Msedge/
    - https://lolbas-project.github.io/lolbas/Binaries/Teams/
    - https://lolbas-project.github.io/lolbas/Binaries/msedgewebview2/
    - https://medium.com/@MalFuzzer/one-electron-to-rule-them-all-dc2e9b263daf
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-10-21
modified: 2024-07-12
tags:
    - attack.execution
logsource:
    category: process_creation
    product: windows
detection:
    selection_parent:
        ParentImage|endswith:
            # Add more electron based app to the list
            - '\chrome.exe' # Might require additional tuning
            - '\discord.exe'
            - '\GitHubDesktop.exe'
            - '\keybase.exe'
            - '\msedge.exe'
            - '\msedgewebview2.exe'
            - '\msteams.exe'
            - '\slack.exe'
            - '\teams.exe'
            # - '\code.exe' # Prone to a lot of FPs. Requires an additional baseline
    selection_child_image:
        Image|endswith:
            # Add more suspicious/unexpected paths
            - '\cmd.exe'
            - '\cscript.exe'
            - '\mshta.exe'
            - '\powershell.exe'
            - '\pwsh.exe'
            - '\regsvr32.exe'
            - '\whoami.exe'
            - '\wscript.exe'
    selection_child_paths:
        Image|contains:
            # Add more suspicious/unexpected paths
            - ':\ProgramData\'
            - ':\Temp\'
            - '\AppData\Local\Temp\'
            - '\Users\Public\'
            - '\Windows\Temp\'
    filter_optional_discord:
        ParentImage|endswith: '\Discord.exe'
        Image|endswith: '\cmd.exe'
        CommandLine|contains: '\NVSMI\nvidia-smi.exe'
    condition: selection_parent and 1 of selection_child_* and not 1 of filter_optional_*
falsepositives:
    - Unknown
# Increase the level once FP rate is reduced (see status)
level: medium