Detection: Windows Njrat Fileless Storage via Registry

Updated Date: 2024-05-23 ID: a5fffbbd-271f-4980-94ed-4fbf17f0af1c Author: Teoderick Contreras, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects suspicious registry modifications indicative of NjRat's fileless storage technique. It leverages the Endpoint.Registry data model to identify specific registry paths and values commonly used by NjRat for keylogging and executing DLL plugins. This activity is significant as it helps evade traditional file-based detection systems, making it crucial for SOC analysts to monitor. If confirmed malicious, this behavior could allow attackers to persist on the host, execute arbitrary code, and capture sensitive keystrokes, leading to potential data breaches and further system compromise.

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Registry where Registry.registry_path="*\\[kl]" OR  Registry.registry_value_data IN ("*[ENTER]*", "*[TAP]*", "*[Back]*") by Registry.dest Registry.user Registry.registry_path Registry.registry_value_data Registry.registry_key_name Registry.registry_value_name 
3| `drop_dm_object_name(Registry)` 
4| `security_content_ctime(lastTime)` 
5| `security_content_ctime(firstTime)` 
6| `windows_njrat_fileless_storage_via_registry_filter`

Data Source

Name Platform Sourcetype Source Supported App
Sysmon EventID 12 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational' N/A

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
windows_njrat_fileless_storage_via_registry_filter search *
windows_njrat_fileless_storage_via_registry_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1027.011 Fileless Storage Defense Evasion
T1027 Obfuscated Files or Information Defense Evasion
KillChainPhase.EXPLOITAITON
NistCategory.DE_CM
Cis18Value.CIS_10
APT32
Turla
APT-C-36
APT3
APT37
APT41
BackdoorDiplomacy
BlackOasis
Earth Lusca
Ember Bear
GALLIUM
Gallmaker
Gamaredon Group
Ke3chang
Kimsuky
Mustang Panda
Rocke
Sandworm Team
Windshift

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the Endpoint datamodel in the Processes node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.

Known False Positives

unknown

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
a suspicious registry entry related to NjRAT keylloging registry in $dest$ 100 100 100
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational xmlwineventlog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational xmlwineventlog

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: GitHub | Version: 2