Detection rules › Sigma

.RDP File Created By Uncommon Application

Status
test
Severity
high
Log source
product windows, category file_event
Author
Nasreddine Bencherchali (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects creation of a file with an ".rdp" extension by an application that doesn't commonly create such files.

MITRE ATT&CK coverage

TacticTechniques
StealthNo specific technique

Event coverage

ProviderEventTitle
SysmonEvent ID 11FileCreate

Rule body yaml

title: .RDP File Created By Uncommon Application
id: fccfb43e-09a7-4bd2-8b37-a5a7df33386d
related:
    - id: f748c45a-f8d3-4e6f-b617-fe176f695b8f
      type: derived
status: test
description: |
    Detects creation of a file with an ".rdp" extension by an application that doesn't commonly create such files.
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)
date: 2023-04-18
modified: 2024-11-01
tags:
    - attack.stealth
logsource:
    product: windows
    category: file_event
detection:
    selection:
        TargetFilename|endswith: '.rdp'
        Image|endswith:
            # Covers browsers
            - '\brave.exe'
            - '\CCleaner Browser\Application\CCleanerBrowser.exe'
            - '\chromium.exe'
            - '\firefox.exe'
            - '\Google\Chrome\Application\chrome.exe'
            - '\iexplore.exe'
            - '\microsoftedge.exe'
            - '\msedge.exe'
            - '\Opera.exe'
            - '\Vivaldi.exe'
            - '\Whale.exe'
            # Covers email clients
            - '\olk.exe' # Outlook
            - '\Outlook.exe'
            - '\RuntimeBroker.exe' # If the windows mail client is used
            - '\Thunderbird.exe'
            # Covers chat applications
            - '\Discord.exe' # Should open the browser for download, but just in case.
            - '\Keybase.exe'
            - '\msteams.exe'
            - '\Slack.exe'
            - '\teams.exe'
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    TargetFilename|endswith: '.rdp'
    Image|endswith:
        - '\brave.exe'
        - '\CCleaner Browser\Application\CCleanerBrowser.exe'
        - '\chromium.exe'
        - '\firefox.exe'
        - '\Google\Chrome\Application\chrome.exe'
        - '\iexplore.exe'
        - '\microsoftedge.exe'
        - '\msedge.exe'
        - '\Opera.exe'
        - '\Vivaldi.exe'
        - '\Whale.exe'
        - '\olk.exe'
        - '\Outlook.exe'
        - '\RuntimeBroker.exe'
        - '\Thunderbird.exe'
        - '\Discord.exe'
        - '\Keybase.exe'
        - '\msteams.exe'
        - '\Slack.exe'
        - '\teams.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.

FieldKindValues
Imageends_with
  • \CCleaner Browser\Application\CCleanerBrowser.exe
  • \Discord.exe corpus 2 (sigma 2)
  • \Google\Chrome\Application\chrome.exe
  • \Keybase.exe corpus 2 (sigma 2)
  • \Opera.exe corpus 11 (sigma 11)
  • \Outlook.exe corpus 14 (sigma 14)
  • \RuntimeBroker.exe corpus 4 (sigma 4)
  • \Slack.exe corpus 2 (sigma 2)
  • \Thunderbird.exe corpus 2 (sigma 2)
  • \Vivaldi.exe corpus 11 (sigma 11)
  • \Whale.exe corpus 3 (sigma 3)
  • \brave.exe corpus 11 (sigma 11)
  • \chromium.exe
  • \firefox.exe corpus 6 (sigma 6)
  • \iexplore.exe corpus 5 (sigma 5)
  • \microsoftedge.exe corpus 3 (sigma 3)
  • \msedge.exe corpus 14 (sigma 14)
  • \msteams.exe corpus 2 (sigma 2)
  • \olk.exe
  • \teams.exe corpus 2 (sigma 2)
TargetFilenameends_with
  • .rdp corpus 2 (sigma 2)