Wdigest Enable UseLogonCredential

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 * Copyright 2025 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

rule wdigest_enable_uselogoncredential {

  meta:
    author = "Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research)"
    description = "Detects potential malicious modification of the property value of UseLogonCredential from HKLM:\\SYSTEM\\CurrentControlSet\\Control\\SecurityProviders\\WDigest to enable clear-text credentials"
    reference = "https://github.com/SigmaHQ/sigma/blob/master/rules/windows/registry/registry_set/registry_set_wdigest_enable_uselogoncredential.yml"
    license = "https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md"
    rule_name = "Wdigest Enable UseLogonCredential"
    rule_id = "mr_b91eeb90-12e0-40f2-878c-a4716fe722bc"
    sigma_uuid = "d6a9b252-c666-4de6-8806-5561bbbd3bdc"
    sigma_status = "test"
    tactic = "TA0005"
    technique = "T1112"
    type = "Detection"
    data_source = "Sysmon Windows Registry"
    platform = "Windows"
    severity = "High"
    priority = "High"
    false_positives = "Unknown"

  events:
    $reg.metadata.event_type = "REGISTRY_MODIFICATION"
    re.regex($reg.target.registry.registry_key, `WDigest\\UseLogonCredential$`) nocase
    $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
}