Detection rules › Splunk
Common Exchange Recon cmdlets (PowerShell)
Detect Common Exchange cmdlet reconnaissance commands used by attackers in order to collect information and/or to spread malware within the network after gaining access to a machine
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Execution | T1059.001 Command and Scripting Interpreter: PowerShell |
| Discovery | T1087.003 Account Discovery: Email Account |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| PowerShell | Event ID 4103 | Payload Context: ContextInfo User Data: UserData. |
| PowerShell | Event ID 4104 | Creating Scriptblock text (MessageNumber of MessageTotal). |
Rule body yaml
id: '5693.5955'
title: Common Exchange Recon cmdlets
description: 'Detect Common Exchange cmdlet reconnaissance commands used by attackers
in order to collect information and/or to spread malware within the network after
gaining access to a machine. - Threat Actor Association: APT29/Nobelium/Cozy Bear,
CL-STA-0043 - Software Association: DatopLoader'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_powershell` (TERM(EventCode=4104) OR
TERM(EventCode=4103)) (TERM(Get-AcceptedDomain) OR TERM(Get-CASMailbox) TERM(Get-Mailbox)
OR TERM(Get-ManagementRoleAssignment) OR TERM(Get-OrganizationConfig) OR TERM(Get-MailboxExportRequest)
OR TERM(Get-OwaVirtualDirectory) OR TERM(Get-WebServicesVirtualDirectory) OR TERM(Get-MailboxRegionalConfiguration)
OR TERM(Get-ExchangeServer) OR TERM(Get-InboxRule) OR TERM(Get-MailboxPermission))
| table _time, host, user signature_id, process, process_* `group_events("host",1s)` '
techniques:
- execution:command and scripting interpreter:powershell
- discovery:account discovery:email account
technique_id:
- T1087.003
- T1059.001
data_category:
- PowerShell logs
- Process command-line parameters
references:
- https://www.volexity.com/blog/2020/12/14/dark-halo-leverages-solarwinds-compromise-to-breach-organizations/
Stages and Predicates
Stage 1: search
search EventCode=4103 EventCode=4104 source="*" source IN ("WinEventLog:Microsoft-Windows-PowerShell/Operational", "WinEventLog:Windows", "XmlWinEventLog:Microsoft-Windows-PowerShell/Operational")
Stage 2: table
table _time, host, process, process_*, signature_id, user
Stage 3: bucket
bucket _time
Stage 4: stats
stats BY host, _time
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
EventCode | eq |
|
Search terms
Bare-string tokens in the SPL search body. Splunk matches each token against _raw (the untyped raw event text) anywhere it appears, not against a specific field. These don't surface in the Indicators table because they aren't predicates on a known field.
| Stage | Term |
|---|---|
| 1 | TERM |
| 1 | TERM |
| 1 | "Get-AcceptedDomain" |
| 1 | "Get-CASMailbox" |
| 1 | "Get-Mailbox" |
| 1 | "Get-ManagementRoleAssignment" |
| 1 | "Get-OrganizationConfig" |
| 1 | "Get-MailboxExportRequest" |
| 1 | "Get-OwaVirtualDirectory" |
| 1 | "Get-WebServicesVirtualDirectory" |
| 1 | "Get-MailboxRegionalConfiguration" |
| 1 | "Get-ExchangeServer" |
| 1 | "Get-InboxRule" |
| 1 | "Get-MailboxPermission" |