NRT Malicious Inbox Rule
Id | b79f6190-d104-4691-b7db-823e05980895 |
Rulename | NRT Malicious Inbox Rule |
Description | Often times after the initial compromise the attackers create inbox rules to delete emails that contain certain keywords. This is done so as to limit ability to warn compromised users that they’ve been compromised. Below is a sample query that tries to detect this. Reference: https://www.reddit.com/r/sysadmin/comments/7kyp0a/recent_phishing_attempts_my_experience_and_what/ |
Severity | Medium |
Tactics | Persistence DefenseEvasion |
Techniques | T1098 T1078 |
Required data connectors | Office365 |
Kind | NRT |
Source Uri | https://github.com/Azure/Azure-Sentinel/blob/master/Detections/OfficeActivity/NRT_Malicious_Inbox_Rule.yaml |
Version | 1.0.2 |
Arm template | b79f6190-d104-4691-b7db-823e05980895.json |
let Keywords = dynamic(["helpdesk", " alert", " suspicious", "fake", "malicious", "phishing", "spam", "do not click", "do not open", "hijacked", "Fatal"]);
OfficeActivity
| where OfficeWorkload =~ "Exchange"
| where Parameters has "Deleted Items" or Parameters has "Junk Email" or Parameters has "DeleteMessage"
| extend Events=todynamic(Parameters)
| parse Events with * "SubjectContainsWords" SubjectContainsWords '}'*
| parse Events with * "BodyContainsWords" BodyContainsWords '}'*
| parse Events with * "SubjectOrBodyContainsWords" SubjectOrBodyContainsWords '}'*
| where SubjectContainsWords has_any (Keywords)
or BodyContainsWords has_any (Keywords)
or SubjectOrBodyContainsWords has_any (Keywords)
| extend ClientIPAddress = case( ClientIP has ".", tostring(split(ClientIP,":")[0]), ClientIP has "[", tostring(trim_start(@'[[]',tostring(split(ClientIP,"]")[0]))), ClientIP )
| extend Keyword = iff(isnotempty(SubjectContainsWords), SubjectContainsWords, (iff(isnotempty(BodyContainsWords),BodyContainsWords,SubjectOrBodyContainsWords )))
| extend RuleDetail = case(OfficeObjectId contains '/' , tostring(split(OfficeObjectId, '/')[-1]) , tostring(split(OfficeObjectId, '\\')[-1]))
| summarize count(), StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated) by UserId, ClientIPAddress, ResultStatus, Keyword, OriginatingServer, OfficeObjectId, RuleDetail
requiredDataConnectors:
- dataTypes:
- OfficeActivity
connectorId: Office365
entityMappings:
- fieldMappings:
- identifier: FullName
columnName: UserId
entityType: Account
- fieldMappings:
- identifier: FullName
columnName: OriginatingServer
entityType: Host
- fieldMappings:
- identifier: Address
columnName: ClientIPAddress
entityType: IP
relevantTechniques:
- T1098
- T1078
version: 1.0.2
id: b79f6190-d104-4691-b7db-823e05980895
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/OfficeActivity/NRT_Malicious_Inbox_Rule.yaml
query: |
let Keywords = dynamic(["helpdesk", " alert", " suspicious", "fake", "malicious", "phishing", "spam", "do not click", "do not open", "hijacked", "Fatal"]);
OfficeActivity
| where OfficeWorkload =~ "Exchange"
| where Parameters has "Deleted Items" or Parameters has "Junk Email" or Parameters has "DeleteMessage"
| extend Events=todynamic(Parameters)
| parse Events with * "SubjectContainsWords" SubjectContainsWords '}'*
| parse Events with * "BodyContainsWords" BodyContainsWords '}'*
| parse Events with * "SubjectOrBodyContainsWords" SubjectOrBodyContainsWords '}'*
| where SubjectContainsWords has_any (Keywords)
or BodyContainsWords has_any (Keywords)
or SubjectOrBodyContainsWords has_any (Keywords)
| extend ClientIPAddress = case( ClientIP has ".", tostring(split(ClientIP,":")[0]), ClientIP has "[", tostring(trim_start(@'[[]',tostring(split(ClientIP,"]")[0]))), ClientIP )
| extend Keyword = iff(isnotempty(SubjectContainsWords), SubjectContainsWords, (iff(isnotempty(BodyContainsWords),BodyContainsWords,SubjectOrBodyContainsWords )))
| extend RuleDetail = case(OfficeObjectId contains '/' , tostring(split(OfficeObjectId, '/')[-1]) , tostring(split(OfficeObjectId, '\\')[-1]))
| summarize count(), StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated) by UserId, ClientIPAddress, ResultStatus, Keyword, OriginatingServer, OfficeObjectId, RuleDetail
metadata:
support:
tier: Community
source:
kind: Community
categories:
domains:
- Security - Threat Protection
author:
name: Pete Bryan
kind: NRT
tactics:
- Persistence
- DefenseEvasion
severity: Medium
name: NRT Malicious Inbox Rule
description: |
'Often times after the initial compromise the attackers create inbox rules to delete emails that contain certain keywords.
This is done so as to limit ability to warn compromised users that they've been compromised. Below is a sample query that tries to detect this.
Reference: https://www.reddit.com/r/sysadmin/comments/7kyp0a/recent_phishing_attempts_my_experience_and_what/'
{
"$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/b79f6190-d104-4691-b7db-823e05980895')]",
"kind": "NRT",
"name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/b79f6190-d104-4691-b7db-823e05980895')]",
"properties": {
"alertRuleTemplateName": "b79f6190-d104-4691-b7db-823e05980895",
"customDetails": null,
"description": "'Often times after the initial compromise the attackers create inbox rules to delete emails that contain certain keywords.\n This is done so as to limit ability to warn compromised users that they've been compromised. Below is a sample query that tries to detect this.\nReference: https://www.reddit.com/r/sysadmin/comments/7kyp0a/recent_phishing_attempts_my_experience_and_what/'\n",
"displayName": "NRT Malicious Inbox Rule",
"enabled": true,
"entityMappings": [
{
"entityType": "Account",
"fieldMappings": [
{
"columnName": "UserId",
"identifier": "FullName"
}
]
},
{
"entityType": "Host",
"fieldMappings": [
{
"columnName": "OriginatingServer",
"identifier": "FullName"
}
]
},
{
"entityType": "IP",
"fieldMappings": [
{
"columnName": "ClientIPAddress",
"identifier": "Address"
}
]
}
],
"OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/OfficeActivity/NRT_Malicious_Inbox_Rule.yaml",
"query": "let Keywords = dynamic([\"helpdesk\", \" alert\", \" suspicious\", \"fake\", \"malicious\", \"phishing\", \"spam\", \"do not click\", \"do not open\", \"hijacked\", \"Fatal\"]);\nOfficeActivity\n| where OfficeWorkload =~ \"Exchange\"\n| where Parameters has \"Deleted Items\" or Parameters has \"Junk Email\" or Parameters has \"DeleteMessage\"\n| extend Events=todynamic(Parameters)\n| parse Events with * \"SubjectContainsWords\" SubjectContainsWords '}'*\n| parse Events with * \"BodyContainsWords\" BodyContainsWords '}'*\n| parse Events with * \"SubjectOrBodyContainsWords\" SubjectOrBodyContainsWords '}'*\n| where SubjectContainsWords has_any (Keywords)\n or BodyContainsWords has_any (Keywords)\n or SubjectOrBodyContainsWords has_any (Keywords)\n| extend ClientIPAddress = case( ClientIP has \".\", tostring(split(ClientIP,\":\")[0]), ClientIP has \"[\", tostring(trim_start(@'[[]',tostring(split(ClientIP,\"]\")[0]))), ClientIP )\n| extend Keyword = iff(isnotempty(SubjectContainsWords), SubjectContainsWords, (iff(isnotempty(BodyContainsWords),BodyContainsWords,SubjectOrBodyContainsWords )))\n| extend RuleDetail = case(OfficeObjectId contains '/' , tostring(split(OfficeObjectId, '/')[-1]) , tostring(split(OfficeObjectId, '\\\\')[-1]))\n| summarize count(), StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated) by UserId, ClientIPAddress, ResultStatus, Keyword, OriginatingServer, OfficeObjectId, RuleDetail\n",
"severity": "Medium",
"subTechniques": [],
"suppressionDuration": "PT1H",
"suppressionEnabled": false,
"tactics": [
"DefenseEvasion",
"Persistence"
],
"techniques": [
"T1078",
"T1098"
],
"templateVersion": "1.0.2"
},
"type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
}
]
}