Techniques
Sample rules
Windows Raccine Scheduled Task Deletion
- source: splunk
- technicques:
- T1562.001
Description
The following analytic identifies the Raccine Rules Updater scheduled task being deleted. Adversaries may attempt to remove this task in order to prevent the update of Raccine. Raccine is a “ransomware vaccine” created by security researcher Florian Roth, designed to intercept and prevent precursors and active ransomware behavior.
Detection logic
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name=schtasks.exe Processes.process="*delete*" AND Processes.process="*Raccine*" by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.original_file_name Processes.process Processes.process_id Processes.parent_process_id
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `windows_raccine_scheduled_task_deletion_filter`
ServicePrincipalNames Discovery with PowerShell
- source: splunk
- technicques:
- T1558.003
Description
The following analytic identifies powershell.exe usage, using Script Block Logging EventCode 4104, related to querying the domain for Service Principle Names. typically, this is a precursor activity related to kerberoasting or the silver ticket attack.
What is a ServicePrincipleName?
A service principal name (SPN) is a unique identifier of a service instance. SPNs are used by Kerberos authentication to associate a service instance with a service logon account. This allows a client application to request that the service authenticate an account even if the client does not have the account name.
The following analytic identifies the use of KerberosRequestorSecurityToken class within the script block. Using .NET System.IdentityModel.Tokens.KerberosRequestorSecurityToken class in PowerShell is the equivelant of using setspn.exe.
During triage, review parallel processes for further suspicious activity.
Detection logic
`powershell` EventCode=4104 ScriptBlockText="*KerberosRequestorSecurityToken*"
| stats count min(_time) as firstTime max(_time) as lastTime by ScriptBlockText Opcode Computer UserID EventCode
| rename Computer as dest
| rename UserID as user
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `serviceprincipalnames_discovery_with_powershell_filter`
Windows Office Product Spawning MSDT
- source: splunk
- technicques:
- T1566
- T1566.001
Description
The following analytic identifies a Microsoft Office product spawning the Windows msdt.exe process. MSDT is a Diagnostics Troubleshooting Wizard native to Windows. This behavior is related to a recently identified sample utilizing protocol handlers to evade preventative controls, including if macros are disabled in the document. During triage, review file modifications for html. In addition, parallel processes including PowerShell and CertUtil.
Detection logic
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name IN ("winword.exe","excel.exe","powerpnt.exe","outlook.exe","mspub.exe","visio.exe","onenote.exe","onenotem.exe","onenoteviewer.exe","onenoteim.exe","msaccess.exe") Processes.process_name=msdt.exe by Processes.dest Processes.user Processes.parent_process_name Processes.parent_process Processes.process_name Processes.original_file_name Processes.process Processes.process_id Processes.parent_process_id
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `windows_office_product_spawning_msdt_filter`