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Description

The following analytic identifies memory dumping using comsvcs.dll with the minidump function with rundll32.exe. This technique is common with adversaries who would like to dump the memory of lsass.exe.

  • Type: TTP
  • Product: Splunk Behavioral Analytics
  • Datamodel: Endpoint_Processes
  • Last Updated: 2022-04-14
  • Author: Jose Hernandez, Michael Haag, Splunk
  • ID: 76bb9e35-f314-4c3d-a385-83c72a13ce4e

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1003.003 NTDS Credential Access
T1003 OS Credential Dumping Credential Access
Kill Chain Phase
  • Actions on Objectives
NIST
  • DE.CM
CIS20
  • CIS 8
  • CIS 16
CVE
1
2
3
4
5
6
| 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)minidump\s+/)=true AND match_regex(process, /(?i)comsvcs.dll\s+/)=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:

:information_source: windows_rundll32_comsvcs_memory_dump_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • 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

RBA

Risk Score Impact Confidence Message
40.0 40 100 A dump of a process was attempted using comsvcs.dll with the minidump function on endpoint $dest_device_id$ by user $dest_device_user$.

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

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: 5