ID | Technique | Tactic |
---|---|---|
T1112 | Modify Registry | Defense Evasion |
Detection: Windows Modify Registry With MD5 Reg Key Name
Description
The following analytic detects potentially malicious registry modifications characterized by MD5-like registry key names. It leverages the Endpoint data model to identify registry entries under the SOFTWARE path with 32-character hexadecimal names, a technique often used by NjRAT malware for fileless storage of keylogs and .DLL plugins. This activity is significant as it can indicate the presence of NjRAT or similar malware, which can lead to unauthorized data access and persistent threats within the environment. If confirmed malicious, attackers could maintain persistence and exfiltrate sensitive information.
Search
1
2| 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
3| `drop_dm_object_name(Registry)`
4| eval dropped_reg_path = split(registry_path, "\\")
5| eval dropped_reg_path_split_count = mvcount(dropped_reg_path)
6| eval validation_result= if(match(registry_value_name,"^[0-9a-fA-F]{32}$"),"md5","nonmd5")
7| where validation_result = "md5" AND dropped_reg_path_split_count <= 5
8| table dest user registry_path registry_value_name registry_value_data registry_key_name reg_key_name dropped_reg_path_split_count validation_result
9| `security_content_ctime(lastTime)`
10| `security_content_ctime(firstTime)`
11| `windows_modify_registry_with_md5_reg_key_name_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
Sysmon EventID 12 | Windows | 'xmlwineventlog' |
'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational' |
N/A |
Macros Used
Name | Value |
---|---|
security_content_ctime | convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$) |
windows_modify_registry_with_md5_reg_key_name_filter | search * |
windows_modify_registry_with_md5_reg_key_name_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
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 |
Implementation
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
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
A md5 registry value name $registry_value_name$ is created on $dest$ | 36 | 60 | 60 |
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