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Detection rules › Sigma

Suspicious Invoke-Item From Mount-DiskImage

Status
test
Severity
medium
Log source
product windows, category ps_script
Author
frack113
Source
github.com/SigmaHQ/sigma

Adversaries may abuse container files such as disk image (.iso, .vhd) file formats to deliver malicious payloads that may not be tagged with MOTW.

MITRE ATT&CK coverage

TacticTechniques
Defense ImpairmentT1553.005 Subvert Trust Controls: Mark-of-the-Web Bypass

Event coverage

ProviderEventTitle
PowerShellEvent ID 4104Creating Scriptblock text (MessageNumber of MessageTotal).

Rule body yaml

title: Suspicious Invoke-Item From Mount-DiskImage
id: 902cedee-0398-4e3a-8183-6f3a89773a96
status: test
description: Adversaries may abuse container files such as disk image (.iso, .vhd) file formats to deliver malicious payloads that may not be tagged with MOTW.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1553.005/T1553.005.md#atomic-test-2---mount-an-iso-image-and-run-executable-from-the-iso
    - https://learn.microsoft.com/en-us/powershell/module/storage/mount-diskimage?view=windowsserver2022-ps
author: frack113
date: 2022-02-01
tags:
    - attack.defense-impairment
    - attack.t1553.005
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection:
        ScriptBlockText|contains|all:
            - 'Mount-DiskImage '
            - '-ImagePath '
            - Get-Volume
            - '.DriveLetter'
            - 'invoke-item '
            - '):\'
    condition: selection
falsepositives:
    - Legitimate PowerShell scripts
level: medium

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    ScriptBlockText|contains|all:
        - 'Mount-DiskImage '
        - '-ImagePath '
        - Get-Volume
        - '.DriveLetter'
        - 'invoke-item '
        - '):\'

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
ScriptBlockTextmatch
  • ):\
  • -ImagePath corpus 2 (sigma 2)
  • .DriveLetter
  • Get-Volume
  • Mount-DiskImage corpus 2 (sigma 2)
  • invoke-item