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Detection rules › YARA-L

Potential Credential Dumping Via LSASS SilentProcessExit Technique

Severity
critical
Type
Detection
Time window
5m
Match by
hostname
Source
github.com/chronicle/detection-rules

Detects changes to the Registry in which a monitor program gets registered to dump the memory of the lsass.exe process

MITRE ATT&CK coverage

TacticTechniques
Credential AccessT1003.001 OS Credential Dumping: LSASS Memory

References

Event coverage

ProviderEventTitle
SysmonEvent ID 13RegistryEvent (Value Set)
Security-AuditingEvent ID 4657A registry value was modified.

Rule body yaral

/*
 * 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 potential_cred_dumping_via_lsass_silentprocessexit_technique {

  meta:
    author = "Florian Roth (Nextron Systems)"
    description = "Detects changes to the Registry in which a monitor program gets registered to dump the memory of the lsass.exe process"
    reference = "https://github.com/SigmaHQ/sigma/blob/master/rules/windows/registry/registry_event/registry_event_silentprocessexit_lsass.yml"
    license = "https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md"
    rule_name = "Potential Credential Dumping Via LSASS SilentProcessExit Technique"
    sigma_uuid = "55e29995-75e7-451a-bef0-6225e2f13597"
    sigma_status = "test"
    rule_id = "mr_bc2279f0-9b27-485d-b392-ff6f13ae68df"
    tactic = "TA0006"
    technique = "T1003.001"
    type = "Detection"
    data_source = "Sysmon"
    platform = "Windows"
    severity = "Critical"
    priority = "Critical"
    false_positives = "Unlikely"

  events:
    $registry.metadata.event_type = "REGISTRY_MODIFICATION"
    //$registry.metadata.product_event_type = "13"
    strings.contains(strings.to_lower($registry.target.registry.registry_key), "microsoft\\windows nt\\currentversion\\silentprocessexit\\lsass.exe")

    $registry.principal.hostname = $hostname

  match:
    $hostname over 5m

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

  condition:
    $registry
}

Stages and Predicates

Stage 0: match + condition

match:
    $hostname over 5m
condition:
    $registry

Fires when at least one $registry event in the 5m window.

Stage 1: events: $registry · REGISTRY_MODIFICATION

$registry.metadata.event_type = "REGISTRY_MODIFICATION"
//$registry.metadata.product_event_type = "13"
strings.contains(strings.to_lower($registry.target.registry.registry_key), "microsoft\\windows nt\\currentversion\\silentprocessexit\\lsass.exe")

$registry.principal.hostname = $hostname

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
target.registry.registry_keycontains
  • microsoft\\windows nt\\currentversion\\silentprocessexit\\lsass.exe transforms: tolower

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

FieldSource
risk_scoremax(if($registry.principal.user.userid = "user" and $registry.principal.hostname = "hostname", 0, 15))
principal_hostnamearray_distinct($registry.principal.hostname)
principal_process_pidarray_distinct($registry.principal.process.pid)
principal_process_file_full_patharray_distinct($registry.principal.process.file.full_path)
principal_process_product_specific_process_idarray_distinct($registry.principal.process.product_specific_process_id)
principal_user_useridarray_distinct($registry.principal.user.userid)
target_registry_keyarray_distinct($registry.target.registry.registry_key)
target_registry_valuearray_distinct($registry.target.registry.registry_value_data)