Detection: Windows KrbRelayUp Service Creation

Updated Date: 2024-09-30 ID: e40ef542-8241-4419-9af4-6324582ea60a Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the creation of a service with the default name "KrbSCM" associated with the KrbRelayUp tool. It leverages Windows System Event Logs, specifically EventCode 7045, to identify this activity. This behavior is significant as KrbRelayUp is a known tool used for privilege escalation attacks. If confirmed malicious, this activity could allow an attacker to escalate privileges, potentially gaining unauthorized access to sensitive systems and data.

1`wineventlog_system` EventCode=7045 ServiceName IN ("KrbSCM") 
2| stats count min(_time) as firstTime max(_time) as lastTime by dest EventCode ImagePath ServiceName StartType ServiceType 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `windows_krbrelayup_service_creation_filter`

Data Source

Name Platform Sourcetype Source
Windows Event Log System 7045 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:System'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
windows_krbrelayup_service_creation_filter search *
windows_krbrelayup_service_creation_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
T1543.003 Windows Service Persistence
KillChainPhase.EXPLOITAITON
KillChainPhase.INSTALLATION
NistCategory.DE_CM
Cis18Value.CIS_10
APT19
APT3
APT32
APT38
APT41
Agrius
Aquatic Panda
Blue Mockingbird
Carbanak
Cinnamon Tempest
Cobalt Group
DarkVishnya
Earth Lusca
FIN7
Ke3chang
Kimsuky
Lazarus Group
PROMETHIUM
TeamTNT
Threat Group-3390
Tropic Trooper
Wizard Spider

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 Windows System Event Logs with 7045 EventCode enabled. The Windows TA is also required.

Known False Positives

False positives should be limited as this is specific to KrbRelayUp based attack. Filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
A service was created on $dest$, related to KrbRelayUp. 64 80 80
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:System XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:System 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: 4