Exchange New Export Request (PowerShell)

Group by: _time, host
Source: github.com/anvilogic-forge/armory

This use case looks for exchange cmdlet to output email into a pst file. Adversaries may use these commands in order to exfiltrate sensitive information. - Threat Group Association: APT, 29, APT31, CL-STA-0043

MITRE ATT&CK coverage

Tactic	Techniques
Collection	`T1114.001` Email Collection: Local Email Collection `T1114.002` Email Collection: Remote Email Collection

References

https://www.volexity.com/blog/2020/12/14/dark-halo-leverages-solarwinds-compromise-to-breach-organizations/

Telemetry coverage

Provider	Record / event type
PowerShell	Event ID 4103: Payload Context: ContextInfo User Data: UserData.
PowerShell	Event ID 4104: Creating Scriptblock text (MessageNumber of MessageTotal).

Rule body

id: '5694.5956'
title: Exchange New Export Request
description: 'This use case looks for exchange cmdlet to output email into a pst file.
  Adversaries may use these commands in order to exfiltrate sensitive information.
  - Threat Group Association: APT, 29, APT31, CL-STA-0043 - Software Association:
  ALPHV/BlackCat, Conti, Hafnium, Qakbot/Qbot, SEABORGIUM'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_powershell` (TERM(EventCode=4104) OR
  TERM(EventCode=4103)) TERM(New-MailboxExportRequest) | regex process="(?i)-FilePath.{1,}\.pst"
  | table _time, host, user signature_id, process, process_* `group_events("host",1s)` '
techniques:
- collection:email collection:local email collection
- collection:email collection:remote email collection
technique_id:
- T1114.002
- T1114.001
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: `regex`

regex match(process, "(?i)-FilePath.{1,}\.pst")

Stage 3: `table`

table _time, host, process, process_*, signature_id, user

Stage 4: `bucket`

bucket _time

Stage 5: `stats`

stats BY host, _time

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`EventCode`	eq	`4103` corpus 105 (splunk 105) `4104` corpus 269 (splunk 269)	`field:"EventID" kind:eq`
`process`	regex_match	`"(?i)-FilePath.{1,}.pst"`	`field:"CommandLine" kind:regex_match`

Search terms

These SPL tokens match against raw event text.

Stage	Term
1	`"New-MailboxExportRequest"`