Mail redirect via ExO transport rule
Id | 500415fb-bba7-4227-a08a-9857fb61b6a7 |
Rulename | Mail redirect via ExO transport rule |
Description | Identifies when Exchange Online transport rule configured to forward emails. This could be an adversary mailbox configured to collect mail from multiple user accounts. |
Severity | Medium |
Tactics | Collection Exfiltration |
Techniques | T1114 T1020 |
Required data connectors | Office365 |
Kind | Scheduled |
Query frequency | 1h |
Query period | 1h |
Trigger threshold | 0 |
Trigger operator | gt |
Source Uri | https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft 365/Analytic Rules/Mail_redirect_via_ExO_transport_rule.yaml |
Version | 2.0.4 |
Arm template | 500415fb-bba7-4227-a08a-9857fb61b6a7.json |
OfficeActivity
| where OfficeWorkload == "Exchange"
| where Operation in~ ("New-TransportRule", "Set-TransportRule")
| mv-apply DynamicParameters = todynamic(Parameters) on (summarize ParsedParameters = make_bag(pack(tostring(DynamicParameters.Name), DynamicParameters.Value)))
| extend RuleName = case(
Operation =~ "Set-TransportRule", OfficeObjectId,
Operation =~ "New-TransportRule", ParsedParameters.Name,
"Unknown")
| mv-expand ExpandedParameters = todynamic(Parameters)
| where ExpandedParameters.Name in~ ("BlindCopyTo", "RedirectMessageTo") and isnotempty(ExpandedParameters.Value)
| extend RedirectTo = ExpandedParameters.Value
| extend ClientIPValues = extract_all(@'\[?(::ffff:)?(?P<IPAddress>(\d+\.\d+\.\d+\.\d+)|[^\]]+)\]?([-:](?P<Port>\d+))?', dynamic(["IPAddress", "Port"]), ClientIP)[0]
| extend From = ParsedParameters.From
| project TimeGenerated, RedirectTo, IPAddress = tostring(ClientIPValues[0]), Port = tostring(ClientIPValues[1]), UserId, From, Operation, RuleName, Parameters
| extend AccountName = tostring(split(UserId, "@")[0]), AccountUPNSuffix = tostring(split(UserId, "@")[1])
status: Available
queryFrequency: 1h
description: |
'Identifies when Exchange Online transport rule configured to forward emails.
This could be an adversary mailbox configured to collect mail from multiple user accounts.'
severity: Medium
version: 2.0.4
relevantTechniques:
- T1114
- T1020
name: Mail redirect via ExO transport rule
triggerThreshold: 0
kind: Scheduled
query: |
OfficeActivity
| where OfficeWorkload == "Exchange"
| where Operation in~ ("New-TransportRule", "Set-TransportRule")
| mv-apply DynamicParameters = todynamic(Parameters) on (summarize ParsedParameters = make_bag(pack(tostring(DynamicParameters.Name), DynamicParameters.Value)))
| extend RuleName = case(
Operation =~ "Set-TransportRule", OfficeObjectId,
Operation =~ "New-TransportRule", ParsedParameters.Name,
"Unknown")
| mv-expand ExpandedParameters = todynamic(Parameters)
| where ExpandedParameters.Name in~ ("BlindCopyTo", "RedirectMessageTo") and isnotempty(ExpandedParameters.Value)
| extend RedirectTo = ExpandedParameters.Value
| extend ClientIPValues = extract_all(@'\[?(::ffff:)?(?P<IPAddress>(\d+\.\d+\.\d+\.\d+)|[^\]]+)\]?([-:](?P<Port>\d+))?', dynamic(["IPAddress", "Port"]), ClientIP)[0]
| extend From = ParsedParameters.From
| project TimeGenerated, RedirectTo, IPAddress = tostring(ClientIPValues[0]), Port = tostring(ClientIPValues[1]), UserId, From, Operation, RuleName, Parameters
| extend AccountName = tostring(split(UserId, "@")[0]), AccountUPNSuffix = tostring(split(UserId, "@")[1])
triggerOperator: gt
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft 365/Analytic Rules/Mail_redirect_via_ExO_transport_rule.yaml
requiredDataConnectors:
- connectorId: Office365
dataTypes:
- OfficeActivity (Exchange)
tactics:
- Collection
- Exfiltration
id: 500415fb-bba7-4227-a08a-9857fb61b6a7
queryPeriod: 1h
entityMappings:
- fieldMappings:
- columnName: UserId
identifier: FullName
- columnName: AccountName
identifier: Name
- columnName: AccountUPNSuffix
identifier: UPNSuffix
entityType: Account
- fieldMappings:
- columnName: IPAddress
identifier: Address
entityType: IP
{
"$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"workspace": {
"type": "String"
}
},
"resources": [
{
"apiVersion": "2024-01-01-preview",
"id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/500415fb-bba7-4227-a08a-9857fb61b6a7')]",
"kind": "Scheduled",
"name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/500415fb-bba7-4227-a08a-9857fb61b6a7')]",
"properties": {
"alertRuleTemplateName": "500415fb-bba7-4227-a08a-9857fb61b6a7",
"customDetails": null,
"description": "'Identifies when Exchange Online transport rule configured to forward emails.\nThis could be an adversary mailbox configured to collect mail from multiple user accounts.'\n",
"displayName": "Mail redirect via ExO transport rule",
"enabled": true,
"entityMappings": [
{
"entityType": "Account",
"fieldMappings": [
{
"columnName": "UserId",
"identifier": "FullName"
},
{
"columnName": "AccountName",
"identifier": "Name"
},
{
"columnName": "AccountUPNSuffix",
"identifier": "UPNSuffix"
}
]
},
{
"entityType": "IP",
"fieldMappings": [
{
"columnName": "IPAddress",
"identifier": "Address"
}
]
}
],
"OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft 365/Analytic Rules/Mail_redirect_via_ExO_transport_rule.yaml",
"query": "OfficeActivity\n| where OfficeWorkload == \"Exchange\"\n| where Operation in~ (\"New-TransportRule\", \"Set-TransportRule\")\n| mv-apply DynamicParameters = todynamic(Parameters) on (summarize ParsedParameters = make_bag(pack(tostring(DynamicParameters.Name), DynamicParameters.Value)))\n| extend RuleName = case(\n Operation =~ \"Set-TransportRule\", OfficeObjectId,\n Operation =~ \"New-TransportRule\", ParsedParameters.Name,\n \"Unknown\")\n| mv-expand ExpandedParameters = todynamic(Parameters)\n| where ExpandedParameters.Name in~ (\"BlindCopyTo\", \"RedirectMessageTo\") and isnotempty(ExpandedParameters.Value)\n| extend RedirectTo = ExpandedParameters.Value\n| extend ClientIPValues = extract_all(@'\\[?(::ffff:)?(?P<IPAddress>(\\d+\\.\\d+\\.\\d+\\.\\d+)|[^\\]]+)\\]?([-:](?P<Port>\\d+))?', dynamic([\"IPAddress\", \"Port\"]), ClientIP)[0]\n| extend From = ParsedParameters.From\n| project TimeGenerated, RedirectTo, IPAddress = tostring(ClientIPValues[0]), Port = tostring(ClientIPValues[1]), UserId, From, Operation, RuleName, Parameters\n| extend AccountName = tostring(split(UserId, \"@\")[0]), AccountUPNSuffix = tostring(split(UserId, \"@\")[1])\n",
"queryFrequency": "PT1H",
"queryPeriod": "PT1H",
"severity": "Medium",
"status": "Available",
"subTechniques": [],
"suppressionDuration": "PT1H",
"suppressionEnabled": false,
"tactics": [
"Collection",
"Exfiltration"
],
"techniques": [
"T1020",
"T1114"
],
"templateVersion": "2.0.4",
"triggerOperator": "GreaterThan",
"triggerThreshold": 0
},
"type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
}
]
}