Blackbyte Ransomware Registry

// Copyright 2025 Google LLC. Licensed under Apache-2.0.

rule blackbyte_ransomware_registry {

  meta:
    author = "frack113"
    description = "BlackByte set three different registry values to escalate privileges and begin setting the stage for lateral movement and encryption"
    reference = "https://github.com/SigmaHQ/sigma/blob/master/rules/windows/registry/registry_set/registry_set_blackbyte_ransomware.yml"
    license = "https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md"
    rule_name = "Blackbyte Ransomware Registry"
    rule_id = "mr_83d31958-2537-4ac7-bee2-1d6e193c892f"
    sigma_uuid = "83314318-052a-4c90-a1ad-660ece38d276"
    sigma_status = "test"
    tactic = "TA0005"
    technique = "T1112"
    type = "Detection"
    data_source = "Windows Registry"
    platform = "Windows"
    severity = "High"
    priority = "High"
    false_positives = "Unknown"

  events:
    $reg.metadata.event_type = "REGISTRY_MODIFICATION"
    (
        $reg.target.registry.registry_key = "HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\LocalAccountTokenFilterPolicy" nocase or
        $reg.target.registry.registry_key = "HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\EnableLinkedConnections" nocase or
        $reg.target.registry.registry_key = "HKLM\\SYSTEM\\CurrentControlSet\\Control\\FileSystem\\LongPathsEnabled" nocase
    ) and $reg.target.registry.registry_value_data = "DWORD (0x00000001)" nocase

    $reg.principal.hostname = $hostname

  match:
    $hostname over 5m

  outcome:
    //example usage of specifying test user and hostname to adjust risk score
    $risk_score = max(if($reg.principal.user.userid = "user" and $reg.principal.hostname = "hostname", 0, 15))
    $principal_hostname = array_distinct($reg.principal.hostname)
    $principal_process_pid = array_distinct($reg.principal.process.pid)
    $principal_process_file_full_path = array_distinct($reg.principal.process.file.full_path)
    $principal_process_product_specific_process_id = array_distinct($reg.principal.process.product_specific_process_id)
    $principal_user_userid = array_distinct($reg.principal.user.userid)
    $target_registry_key = array_distinct($reg.target.registry.registry_key)
    $target_registry_value_data = array_distinct($reg.target.registry.registry_value_data)
    $log_type = array_distinct(strings.concat($reg.metadata.log_type,"/",$reg.metadata.product_event_type))

  condition:
    $reg
}