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Description

The following analytic identifies credential dumping using comsvcs.dll with regsvr32.exe. This technique is common with adversaries who would like to dump the memory of lsass.exe and perform offline password cracking.

  • Type: TTP
  • Product: Splunk Behavioral Analytics
  • Datamodel: Endpoint_Processes
  • Last Updated: 2021-11-29
  • Author: Jose Hernandez, Splunk
  • ID: 76bb9e35-f314-4c3d-a385-83c72a13ce4e

ATT&CK

ID Technique Tactic
T1003.003 NTDS Credential Access
T1003 OS Credential Dumping Credential Access
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| from read_ssa_enriched_events() 
| eval tenant=ucast(map_get(input_event, "_tenant"), "string", null), machine=ucast(map_get(input_event, "dest_device_id"), "string", null), process_name=lower(ucast(map_get(input_event, "process_name"), "string", null)), timestamp=parse_long(ucast(map_get(input_event, "_time"), "string", null)), process=lower(ucast(map_get(input_event, "process"), "string", null)), event_id=ucast(map_get(input_event, "event_id"), "string", null) 
| where process IS NOT NULL AND process_name IS NOT NULL AND process_name LIKE "%rundll32.exe%" AND match_regex(process, /(?i)comsvcs.dll[,\s]+MiniDump/)=true 
| eval start_time = timestamp, end_time = timestamp, entities = mvappend(machine), body=create_map(["event_id", event_id, "process_name", process_name, "process", process]) 
| into write_ssa_detected_events();

Macros

The SPL above uses the following Macros:

Note that detect_dump_lsass_memory_using_comsvcs_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

  • process_name
  • _tenant
  • _time
  • dest_device_id
  • process

How To Implement

You must be ingesting endpoint data that tracks process activity, including Windows command line logging. You can see how we test this with Event Code 4688 on the attack_range.

Known False Positives

False positives should be limited, filter as needed.

Associated Analytic story

Kill Chain Phase

  • Actions on Objectives

RBA

Risk Score Impact Confidence Message
70.0 70 100 A dump of lsass.exe was attempted using comsvcs.dll on endpoint $dest_device_id$ by user $dest_device_user$.

Note that risk score is calculated base on the following formula: (Impact * Confidence)/100

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

source | version: 2