Potentially Suspicious CMD Shell Output Redirect — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: medium. Source dates: 2022-07-12 / 2024-03-19.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 00d33cac2234b52d5515247550107b02cce63eb78d6551456bb77dae4bcaf76b

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Potentially Suspicious CMD Shell Output Redirect
id: 8e0bb260-d4b2-4fff-bb8d-3f82118e6892
related:
    - id: aa2efee7-34dd-446e-8a37-40790a66efd7
      type: derived
    - id: 4f4eaa9f-5ad4-410c-a4be-bc6132b0175a
      type: similar
status: test
description: |
    Detects inline Windows shell commands redirecting output via the ">" symbol to a suspicious location.
    This technique is sometimes used by malicious actors in order to redirect the output of reconnaissance commands such as "hostname" and "dir" to files for future exfiltration.
references:
    - https://thedfirreport.com/2022/07/11/select-xmrig-from-sqlserver/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-07-12
modified: 2024-03-19
tags:
    - attack.stealth
    - attack.t1218
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\cmd.exe'
        - OriginalFileName: 'Cmd.Exe'
    selection_cli_1:
        CommandLine|contains:
            # Note: Add more suspicious locations as you find them
            # Note: The space from the start is missing to cover append operations ">>"
            # Note: We use the "?" to account for both a single and a double quote
            # Note: If you want to account for more spaces which is still a valid bypass option. Use a regex with "\s"
            - '>?%APPDATA%\'
            - '>?%TEMP%\'
            - '>?%TMP%\'
            - '>?%USERPROFILE%\'
            - '>?C:\ProgramData\'
            - '>?C:\Temp\'
            - '>?C:\Users\Public\'
            - '>?C:\Windows\Temp\'
    selection_cli_2:
        CommandLine|contains:
            - ' >'
            - '">'
            - "'>"
        CommandLine|contains|all:
            - 'C:\Users\'
            - '\AppData\Local\'
    condition: selection_img and 1 of selection_cli_*
falsepositives:
    - Legitimate admin or third party scripts used for diagnostic collection might generate some false positives
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate admin or third party scripts used for diagnostic collection might generate some false positives

Source references

• https://thedfirreport.com/2022/07/11/select-xmrig-from-sqlserver/