:warning: THIS IS A EXPERIMENTAL DETECTION

This detection has been marked experimental by the Splunk Threat Research team. This means we have not been able to test, simulate, or build datasets for this detection. Use at your own risk. This analytic is NOT supported.

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Description

The following hunting analytic leverages Event ID 7045, A new service was installed in the system, to identify the installation of a Windows Service with a suspicious, high entropy, Service Name. To achieve this, this analytic also leverages the ut_shannon function from the URL ToolBox Splunk application. Red teams and adversaries alike may abuse the Service Control Manager to create and start a remote Windows Service and obtain remote code execution. To achieve this goal, some tools like Metasploit, Cobalt Strike and Impacket, typically create a Windows Service with a random service name on the victim host. This hunting analytic may help defenders identify Windows Services installed as part of a lateral movement attack. The entropy threshold ut_shannon > 3 should be customized by users. The Service_File_Name field can be used to determine if the Windows Service has malicious intent or not.

  • Type: Hunting

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2021-11-29
  • Author: Mauricio Velazco, Splunk
  • ID: 2032a95a-5165-11ec-a2c3-3e22fbd008af

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1543 Create or Modify System Process Persistence, Privilege Escalation
T1543.003 Windows Service Persistence, Privilege Escalation
Kill Chain Phase
  • Installation
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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 `wineventlog_system` EventCode=7045 
| lookup ut_shannon_lookup word as Service_Name 
| where ut_shannon > 3 
| table EventCode ComputerName Service_Name ut_shannon Service_Start_Type Service_Type Service_File_Name 
| `randomly_generated_windows_service_name_filter`

Macros

The SPL above uses the following Macros:

:information_source: randomly_generated_windows_service_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
  • EventCode
  • ComputerName
  • Service_File_Name
  • Service_Type
  • Service_Name
  • Service_Start_Type

How To Implement

To successfully implement this search, you need to be ingesting logs with the Service name, Service File Name Service Start type, and Service Type from your endpoints. The Windows TA as well as the URL ToolBox application are also required.

Known False Positives

Legitimate applications may use random Windows Service names.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
45.0 90 50 A Windows Service with a suspicious service name was installed on $ComputerName$

: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