Potential Data Exfiltration Via Audio File

title: Potential Data Exfiltration Via Audio File
id: e4f93c99-396f-47c8-bb0f-201b1fa69034
status: test
description: Detects potential exfiltration attempt via audio file using PowerShell
references:
    - https://github.com/gtworek/PSBits/blob/e97cbbb173b31cbc4d37244d3412de0a114dacfb/NoDLP/bin2wav.ps1
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-01-16
tags:
    - attack.exfiltration
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection_main:
        ScriptBlockText|contains|all:
            - '[System.Math]::'
            - '[IO.FileMode]::'
            - 'BinaryWriter'
    selection_header_wav:
        ScriptBlockText|contains|all:
            # Byte chunks from the WAV header used in the example POC
            # You can extend this for different audio formats by adding different selections
            - '0x52'
            - '0x49'
            - '0x46'
            - '0x57'
            - '0x41'
            - '0x56'
            - '0x45'
            - '0xAC'
    condition: selection_main and 1 of selection_header_*
falsepositives:
    - Unknown
level: medium