PowerShell 4104 Hunting

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Description

The following Hunting analytic assists with identifying suspicious PowerShell execution using Script Block Logging, or EventCode 4104. This analytic is not meant to be ran hourly, but occasionally to identify malicious or suspicious PowerShell. This analytic is a combination of work completed by Alex Teixeira and Splunk Threat Research Team.

• Type: Hunting

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

• Last Updated: 2023-06-14
• Author: Michael Haag, Splunk
• ID: d6f2b006-0041-11ec-8885-acde48001122

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1059	Command and Scripting Interpreter	Execution

T1059.001

PowerShell

Execution

Kill Chain Phase

• Installation

NIST

• DE.AE

CIS20

• CIS 10

CVE

Search

`powershell` EventCode=4104 
| eval DoIt = if(match(ScriptBlockText,"(?i)(\$doit)"), "4", 0) 
| eval enccom=if(match(ScriptBlockText,"[A-Za-z0-9+\/]{44,}([A-Za-z0-9+\/]{4}
|[A-Za-z0-9+\/]{3}=
|[A-Za-z0-9+\/]{2}==)") OR match(ScriptBlockText, "(?i)[-]e(nc*o*d*e*d*c*o*m*m*a*n*d*)*\s+[^-]"),4,0) 
| eval suspcmdlet=if(match(ScriptBlockText, "(?i)Add-Exfiltration
|Add-Persistence
|Add-RegBackdoor
|Add-ScrnSaveBackdoor
|Check-VM
|Do-Exfiltration
|Enabled-DuplicateToken
|Exploit-Jboss
|Find-Fruit
|Find-GPOLocation
|Find-TrustedDocuments
|Get-ApplicationHost
|Get-ChromeDump
|Get-ClipboardContents
|Get-FoxDump
|Get-GPPPassword
|Get-IndexedItem
|Get-Keystrokes
|LSASecret
|Get-PassHash
|Get-RegAlwaysInstallElevated
|Get-RegAutoLogon
|Get-RickAstley
|Get-Screenshot
|Get-SecurityPackages
|Get-ServiceFilePermission
|Get-ServicePermission
|Get-ServiceUnquoted
|Get-SiteListPassword
|Get-System
|Get-TimedScreenshot
|Get-UnattendedInstallFile
|Get-Unconstrained
|Get-VaultCredential
|Get-VulnAutoRun
|Get-VulnSchTask
|Gupt-Backdoor
|HTTP-Login
|Install-SSP
|Install-ServiceBinary
|Invoke-ACLScanner
|Invoke-ADSBackdoor
|Invoke-ARPScan
|Invoke-AllChecks
|Invoke-BackdoorLNK
|Invoke-BypassUAC
|Invoke-CredentialInjection
|Invoke-DCSync
|Invoke-DllInjection
|Invoke-DowngradeAccount
|Invoke-EgressCheck
|Invoke-Inveigh
|Invoke-InveighRelay
|Invoke-Mimikittenz
|Invoke-NetRipper
|Invoke-NinjaCopy
|Invoke-PSInject
|Invoke-Paranoia
|Invoke-PortScan
|Invoke-PoshRat
|Invoke-PostExfil
|Invoke-PowerDump
|Invoke-PowerShellTCP
|Invoke-PsExec
|Invoke-PsUaCme
|Invoke-ReflectivePEInjection
|Invoke-ReverseDNSLookup
|Invoke-RunAs
|Invoke-SMBScanner
|Invoke-SSHCommand
|Invoke-Service
|Invoke-Shellcode
|Invoke-Tater
|Invoke-ThunderStruck
|Invoke-Token
|Invoke-UserHunter
|Invoke-VoiceTroll
|Invoke-WScriptBypassUAC
|Invoke-WinEnum
|MailRaider
|New-HoneyHash
|Out-Minidump
|Port-Scan
|PowerBreach
|PowerUp
|PowerView
|Remove-Update
|Set-MacAttribute
|Set-Wallpaper
|Show-TargetScreen
|Start-CaptureServer
|VolumeShadowCopyTools
|NEEEEWWW
|(Computer
|User)Property
|CachedRDPConnection
|get-net\S+
|invoke-\S+hunter
|Install-Service
|get-\S+(credent
|password)
|remoteps
|Kerberos.*(policy
|ticket)
|netfirewall
|Uninstall-Windows
|Verb\s+Runas
|AmsiBypass
|nishang
|Invoke-Interceptor
|EXEonRemote
|NetworkRelay
|PowerShelludp
|PowerShellIcmp
|CreateShortcut
|copy-vss
|invoke-dll
|invoke-mass
|out-shortcut
|Invoke-ShellCommand"),1,0) 
| eval base64 = if(match(lower(ScriptBlockText),"frombase64"), "4", 0) 
| eval empire=if(match(lower(ScriptBlockText),"system.net.webclient") AND match(lower(ScriptBlockText), "frombase64string") ,5,0) 
| eval mimikatz=if(match(lower(ScriptBlockText),"mimikatz") OR match(lower(ScriptBlockText), "-dumpcr") OR match(lower(ScriptBlockText), "SEKURLSA::Pth") OR match(lower(ScriptBlockText), "kerberos::ptt") OR match(lower(ScriptBlockText), "kerberos::golden") ,5,0) 
| eval iex=if(match(ScriptBlockText, "(?i)iex
|invoke-expression"),2,0) 
| eval webclient=if(match(lower(ScriptBlockText),"http") OR match(lower(ScriptBlockText),"web(client
|request)") OR match(lower(ScriptBlockText),"socket") OR match(lower(ScriptBlockText),"download(file
|string)") OR match(lower(ScriptBlockText),"bitstransfer") OR match(lower(ScriptBlockText),"internetexplorer.application") OR match(lower(ScriptBlockText),"xmlhttp"),5,0) 
| eval get = if(match(lower(ScriptBlockText),"get-"), "1", 0) 
| eval rundll32 = if(match(lower(ScriptBlockText),"rundll32"), "4", 0) 
| eval suspkeywrd=if(match(ScriptBlockText, "(?i)(bitstransfer
|mimik
|metasp
|AssemblyBuilderAccess
|Reflection\.Assembly
|shellcode
|injection
|cnvert
|shell\.application
|start-process
|Rc4ByteStream
|System\.Security\.Cryptography
|lsass\.exe
|localadmin
|LastLoggedOn
|hijack
|BackupPrivilege
|ngrok
|comsvcs
|backdoor
|brute.?force
|Port.?Scan
|Exfiltration
|exploit
|DisableRealtimeMonitoring
|beacon)"),1,0) 
| eval syswow64 = if(match(lower(ScriptBlockText),"syswow64"), "3", 0) 
| eval httplocal = if(match(lower(ScriptBlockText),"http://127.0.0.1"), "4", 0) 
| eval reflection = if(match(lower(ScriptBlockText),"reflection"), "1", 0) 
| eval invokewmi=if(match(lower(ScriptBlockText), "(?i)(wmiobject
|WMIMethod
|RemoteWMI
|PowerShellWmi
|wmicommand)"),5,0) 
| eval downgrade=if(match(ScriptBlockText, "(?i)([-]ve*r*s*i*o*n*\s+2)") OR match(lower(ScriptBlockText),"powershell -version"),3,0) 
| eval compressed=if(match(ScriptBlockText, "(?i)GZipStream
|::Decompress
|IO.Compression
|write-zip
|(expand
|compress)-Archive"),5,0) 
| eval invokecmd = if(match(lower(ScriptBlockText),"invoke-command"), "4", 0) 
| addtotals fieldname=Score DoIt, enccom, suspcmdlet, suspkeywrd, compressed, downgrade, mimikatz, iex, empire, rundll32, webclient, syswow64, httplocal, reflection, invokewmi, invokecmd, base64, get 
| stats values(Score) by UserID, Computer, DoIt, enccom, compressed, downgrade, iex, mimikatz, rundll32, empire, webclient, syswow64, httplocal, reflection, invokewmi, invokecmd, base64, get, suspcmdlet, suspkeywrd 
| rename Computer as dest, UserID as user 
| `powershell_4104_hunting_filter`

Macros

The SPL above uses the following Macros:

• powershell

powershell_4104_hunting_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
• ScriptBlockText
• Opcode
• Computer
• UserID
• EventCode

How To Implement

The following Hunting analytic requires PowerShell operational logs to be imported. Modify the powershell macro as needed to match the sourcetype or add index. This analytic is specific to 4104, or PowerShell Script Block Logging.

Known False Positives

Limited false positives. May filter as needed.

Associated Analytic Story

• Malicious PowerShell
• Hermetic Wiper
• Data Destruction
• Flax Typhoon

RBA

Risk Score	Impact	Confidence	Message
80.0	80	100	Powershell was identified on endpoint $host$ by user $user$ executing suspicious commands.

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://github.com/inodee/threathunting-spl/blob/master/hunt-queries/powershell_qualifiers.md
• https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell
• https://github.com/marcurdy/dfir-toolset/blob/master/Powershell%20Blueteam.txt
• https://devblogs.microsoft.com/powershell/powershell-the-blue-team/
• https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_logging?view=powershell-5.1
• https://www.mandiant.com/resources/greater-visibilityt
• https://hurricanelabs.com/splunk-tutorials/how-to-use-powershell-transcription-logs-in-splunk/
• https://www.splunk.com/en_us/blog/security/hunting-for-malicious-powershell-using-script-block-logging.html
• https://adlumin.com/post/powerdrop-a-new-insidious-powershell-script-for-command-and-control-attacks-targets-u-s-aerospace-defense-industry/

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

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