ProofpointPOD - Multiple protected emails to unknown recipient

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Id	f8127962-7739-4211-a4a9-390a7a00e91f
Rulename	ProofpointPOD - Multiple protected emails to unknown recipient
Description	Detects when multiple protected messages where sent to early not seen recipient.
Severity	Medium
Tactics	Exfiltration
Techniques	T1567
Required data connectors	ProofpointPOD
Kind	Scheduled
Query frequency	30m
Query period	30m
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Proofpoint On demand(POD) Email Security/Analytic Rules/ProofpointPODMultipleProtectedEmailsToUnknownRecipient.yaml
Version	1.1.1
Arm template	f8127962-7739-4211-a4a9-390a7a00e91f.json

KQL

let lbtime = 30m;
let lbperiod = 14d;
let knownrecipients = ProofpointPOD
| where TimeGenerated > ago(lbperiod)
| where EventType == 'message'
| where NetworkDirection == 'outbound'
| where SrcUserUpn != ''
| where array_length(todynamic(DstUserUpn)) == 1
| summarize recipients = make_set(tostring(todynamic(DstUserUpn)[0])) by SrcUserUpn
| extend commcol = SrcUserUpn;
ProofpointPOD
| where TimeGenerated between (ago(lbtime) .. now())
| where EventType == 'message'
| where NetworkDirection == 'outbound'
| extend isProtected = todynamic(MsgParts)[0]['isProtected']
| extend mimePgp = todynamic(MsgParts)[0]['detectedMime']
| where isProtected == 'true' or mimePgp == 'application/pgp-encrypted'
| extend DstUserMail = tostring(todynamic(DstUserUpn)[0])
| extend commcol = tostring(todynamic(DstUserUpn)[0])
| join knownrecipients on commcol
| where recipients !contains DstUserMail
| project SrcUserUpn, DstUserMail
| extend AccountCustomEntity = SrcUserUpn

YAML

entityMappings:
- fieldMappings:
  - columnName: AccountCustomEntity
    identifier: FullName
  entityType: Account
triggerOperator: gt
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Proofpoint On demand(POD) Email Security/Analytic Rules/ProofpointPODMultipleProtectedEmailsToUnknownRecipient.yaml
version: 1.1.1
tactics:
- Exfiltration
queryPeriod: 30m
kind: Scheduled
id: f8127962-7739-4211-a4a9-390a7a00e91f
severity: Medium
query: |
  let lbtime = 30m;
  let lbperiod = 14d;
  let knownrecipients = ProofpointPOD
  | where TimeGenerated > ago(lbperiod)
  | where EventType == 'message'
  | where NetworkDirection == 'outbound'
  | where SrcUserUpn != ''
  | where array_length(todynamic(DstUserUpn)) == 1
  | summarize recipients = make_set(tostring(todynamic(DstUserUpn)[0])) by SrcUserUpn
  | extend commcol = SrcUserUpn;
  ProofpointPOD
  | where TimeGenerated between (ago(lbtime) .. now())
  | where EventType == 'message'
  | where NetworkDirection == 'outbound'
  | extend isProtected = todynamic(MsgParts)[0]['isProtected']
  | extend mimePgp = todynamic(MsgParts)[0]['detectedMime']
  | where isProtected == 'true' or mimePgp == 'application/pgp-encrypted'
  | extend DstUserMail = tostring(todynamic(DstUserUpn)[0])
  | extend commcol = tostring(todynamic(DstUserUpn)[0])
  | join knownrecipients on commcol
  | where recipients !contains DstUserMail
  | project SrcUserUpn, DstUserMail
  | extend AccountCustomEntity = SrcUserUpn  
triggerThreshold: 0
name: ProofpointPOD - Multiple protected emails to unknown recipient
status: Available
description: |
    'Detects when multiple protected messages where sent to early not seen recipient.'
relevantTechniques:
- T1567
requiredDataConnectors:
- connectorId: ProofpointPOD
  dataTypes:
  - ProofpointPOD_message_CL
queryFrequency: 30m

ARM