Try in Splunk Security Cloud

Description

This analytic is designed to identify potentially malicious registry modification characterized by MD5-like registry key names. This technique has been notably observed in NjRAT malware, which employs such registries for fileless storage of keylogs and .DLL plugins. Detecting this tactic serves as an effective means of identifying possible NjRAT malware instances that create or modify registries as part of their malicious activities.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2023-09-25
  • Author: Teoderick Contreras, Splunk
  • ID: 4662c6b1-0754-455e-b9ff-3ee730af3ba8

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1112 Modify Registry Defense Evasion
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


1
2
3
4
5
6
7
8
9
10
11



| tstats `security_content_summariesonly`  count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Registry where  Registry.registry_path = "*\\SOFTWARE\\*" Registry.registry_value_data = "Binary Data" by Registry.dest Registry.user Registry.registry_path Registry.registry_value_name Registry.registry_value_data Registry.registry_key_name 
| `drop_dm_object_name(Registry)` 
| eval dropped_reg_path = split(registry_path, "\\") 
| eval dropped_reg_path_split_count = mvcount(dropped_reg_path) 
| eval validation_result= if(match(registry_value_name,"^[0-9a-fA-F]{32}$"),"md5","nonmd5") 
| where validation_result = "md5" AND dropped_reg_path_split_count <= 5 
| table dest user registry_path registry_value_name registry_value_data registry_key_name reg_key_name dropped_reg_path_split_count validation_result 
| `security_content_ctime(lastTime)` 
| `security_content_ctime(firstTime)` 
| `windows_modify_registry_with_md5_reg_key_name_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_modify_registry_with_md5_reg_key_name_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.

  • _time
  • Registry.registry_key_name
  • Registry.registry_path
  • Registry.user
  • Registry.dest
  • Registry.registry_value_name
  • Registry.action
  • Registry.registry_value_data

How To Implement

To successfully implement this search you need to be ingesting information on process that include the name of the Filesystem responsible for the changes from your endpoints into the Endpoint datamodel in the Filesystem node.

Known False Positives

unknown

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
36.0 60 60 A md5 registry value name $registry_value_name$ is created on $dest$

: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: 1