Windows Hunting System Account Targeting Lsass

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Description

The following hunting analytic identifies all processes requesting access into Lsass.exe. his behavior may be related to credential dumping or applications requiring access to credentials. Triaging this event will require understanding the GrantedAccess from the SourceImage. In addition, whether the account is privileged or not. Review the process requesting permissions and review parallel processes.

• Type: Hunting

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

• Last Updated: 2022-01-12
• Author: Michael Haag, Splunk
• ID: 1c6abb08-73d1-11ec-9ca0-acde48001122

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1003.001	LSASS Memory	Credential Access

T1003

OS Credential Dumping

Credential Access

Kill Chain Phase

• Exploitation

NIST

• DE.AE

CIS20

• CIS 10

CVE

Search

`sysmon` EventCode=10 TargetImage=*lsass.exe 
| stats count min(_time) as firstTime max(_time) as lastTime by dest, TargetImage, GrantedAccess, SourceImage, SourceProcessId, SourceUser, TargetUser  
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_hunting_system_account_targeting_lsass_filter`

Macros

The SPL above uses the following Macros:

• sysmon
• security_content_ctime

windows_hunting_system_account_targeting_lsass_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
• dest
• TargetImage
• GrantedAccess
• SourceImage
• SourceProcessId
• SourceUser
• TargetUser

How To Implement

To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. Enabling EventCode 10 TargetProcess lsass.exe is required.

Known False Positives

False positives will occur based on GrantedAccess and SourceUser, filter based on source image as needed. Utilize this hunting analytic to tune out false positives in TTP or anomaly analytics.

Associated Analytic Story

• Credential Dumping

RBA

Risk Score	Impact	Confidence	Message
64.0	80	80	A process, $SourceImage$, has requested access to LSASS on $dest$. Review for further details.

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

• https://en.wikipedia.org/wiki/Local_Security_Authority_Subsystem_Service
• https://docs.microsoft.com/en-us/windows/win32/api/minidumpapiset/nf-minidumpapiset-minidumpwritedump
• https://cyberwardog.blogspot.com/2017/03/chronicles-of-threat-hunter-hunting-for_22.html
• https://raw.githubusercontent.com/PowerShellMafia/PowerSploit/master/Exfiltration/Invoke-Mimikatz.ps1
• https://docs.microsoft.com/en-us/windows/win32/procthread/process-security-and-access-rights?redirectedfrom=MSDN

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