Dump LSASS via comsvcs DLL

SPLUNK detection rule by Patrick Bareiss, Splunk · Apache-2.0

The following analytic detects the behavior of dumping credentials from memory by exploiting the Local Security Authority Subsystem Service (LSASS) using the comsvcs.dll and MiniDump via rundll32. This detection leverages process information from Endpoint Detection and Response (EDR) logs, focusing on specific command-line executions. This activity is significant because it indicates potential credential theft, which can lead to broader system compromise, persistence, lateral movement, and privilege escalation. If confirmed malicious, attackers could gain unauthorized access to sensitive information, leading to data theft, ransomware attacks, or other damaging outcomes.

name: Dump LSASS via comsvcs DLL
id: 8943b567-f14d-4ee8-a0bb-2121d4ce3184
version: 17
creation_date: '2019-10-16'
modification_date: '2026-05-13'
author: Patrick Bareiss, Splunk
status: production
type: TTP
description: The following analytic detects the behavior of dumping credentials from memory by exploiting the Local Security Authority Subsystem Service (LSASS) using the comsvcs.dll and MiniDump via rundll32. This detection leverages process information from Endpoint Detection and Response (EDR) logs, focusing on specific command-line executions. This activity is significant because it indicates potential credential theft, which can lead to broader system compromise, persistence, lateral movement, and privilege escalation. If confirmed malicious, attackers could gain unauthorized access to sensitive information, leading to data theft, ransomware attacks, or other damaging outcomes.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
search: |-
    | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
      WHERE `process_rundll32` Processes.process=*comsvcs.dll* Processes.process IN ("*MiniDump*", "*#24*")
      BY Processes.action Processes.dest Processes.original_file_name
         Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
         Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
         Processes.process Processes.process_exec Processes.process_guid
         Processes.process_hash Processes.process_id Processes.process_integrity_level
         Processes.process_name Processes.process_path Processes.user
         Processes.user_id Processes.vendor_product
    | `drop_dm_object_name(Processes)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `dump_lsass_via_comsvcs_dll_filter`
how_to_implement: The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
known_false_positives: No false positives have been identified at this time.
references:
    - https://modexp.wordpress.com/2019/08/30/minidumpwritedump-via-com-services-dll/
    - https://twitter.com/SBousseaden/status/1167417096374050817
    - https://www.microsoft.com/en-us/security/blog/2023/05/24/volt-typhoon-targets-us-critical-infrastructure-with-living-off-the-land-techniques/
drilldown_searches:
    - name: View the detection results for - "$user$" and "$dest$"
      search: '%original_detection_search% | search  user = "$user$" dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$user$" and "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$", "$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
finding:
    title: An instance of $parent_process_name$ spawning $process_name$ was identified accessing credentials using comsvcs.dll on endpoint $dest$ by user $user$.
    entity:
        field: user
        type: user
        score: 50
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 50
          message: An instance of $parent_process_name$ spawning $process_name$ was identified accessing credentials using comsvcs.dll on endpoint $dest$ by user $user$.
threat_objects:
    - field: parent_process_name
      type: parent_process_name
    - field: process_name
      type: process_name
analytic_story:
    - Living Off The Land
    - CISA AA22-257A
    - Volt Typhoon
    - HAFNIUM Group
    - Prestige Ransomware
    - Suspicious Rundll32 Activity
    - Industroyer2
    - Data Destruction
    - Flax Typhoon
    - CISA AA22-264A
    - Compromised Windows Host
    - Credential Dumping
    - Scattered Lapsus$ Hunters
    - Hellcat Ransomware
asset_type: Endpoint
mitre_attack_id:
    - T1003.001
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1003.001/atomic_red_team/windows-sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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