Base64 encoded Windows process command-lines Normalized Process Events
Id | f8b3c49c-4087-499b-920f-0dcfaff0cbca |
Rulename | Base64 encoded Windows process command-lines (Normalized Process Events) |
Description | Identifies instances of a base64 encoded PE file header seen in the process command line parameter. To use this analytics rule, make sure you have deployed the ASIM normalization parsers |
Severity | Medium |
Tactics | Execution DefenseEvasion |
Techniques | T1059 T1027 T1140 |
Kind | Scheduled |
Query frequency | 1d |
Query period | 1d |
Trigger threshold | 0 |
Trigger operator | gt |
Source Uri | https://github.com/Azure/Azure-Sentinel/blob/master/Detections/ASimProcess/imProcess_base64_encoded_pefile.yaml |
Version | 1.1.4 |
Arm template | f8b3c49c-4087-499b-920f-0dcfaff0cbca.json |
imProcessCreate
| where CommandLine contains "TVqQAAMAAAAEAAA"
| where isnotempty(Process)
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated), count() by Dvc, ActorUsername, Process, CommandLine, ActingProcessName, EventVendor, EventProduct
| extend AccountName = tostring(split(ActorUsername, @'\')[1]), AccountNTDomain = tostring(split(ActorUsername, @'\')[0])
| extend HostName = tostring(split(Dvc, ".")[0]), DomainIndex = toint(indexof(Dvc, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Dvc, DomainIndex + 1), Dvc)
| project-away DomainIndex
id: f8b3c49c-4087-499b-920f-0dcfaff0cbca
triggerOperator: gt
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/ASimProcess/imProcess_base64_encoded_pefile.yaml
requiredDataConnectors: []
description: |
'Identifies instances of a base64 encoded PE file header seen in the process command line parameter.
To use this analytics rule, make sure you have deployed the [ASIM normalization parsers](https://aka.ms/ASimProcessEvent)'
severity: Medium
queryPeriod: 1d
kind: Scheduled
tags:
- Id: ca67c83e-7fff-4127-a3e3-1af66d6d4cad
version: 1.0.0
- SchemaVersion: 0.1.0
Schema: ASIMProcessEvent
tactics:
- Execution
- DefenseEvasion
queryFrequency: 1d
query: |
imProcessCreate
| where CommandLine contains "TVqQAAMAAAAEAAA"
| where isnotempty(Process)
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated), count() by Dvc, ActorUsername, Process, CommandLine, ActingProcessName, EventVendor, EventProduct
| extend AccountName = tostring(split(ActorUsername, @'\')[1]), AccountNTDomain = tostring(split(ActorUsername, @'\')[0])
| extend HostName = tostring(split(Dvc, ".")[0]), DomainIndex = toint(indexof(Dvc, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Dvc, DomainIndex + 1), Dvc)
| project-away DomainIndex
version: 1.1.4
triggerThreshold: 0
name: Base64 encoded Windows process command-lines (Normalized Process Events)
entityMappings:
- entityType: Account
fieldMappings:
- columnName: ActorUsername
identifier: FullName
- columnName: AccountName
identifier: Name
- columnName: AccountNTDomain
identifier: NTDomain
- entityType: Host
fieldMappings:
- columnName: Dvc
identifier: FullName
- columnName: HostName
identifier: HostName
- columnName: HostNameDomain
identifier: DnsDomain
relevantTechniques:
- T1059
- T1027
- T1140
metadata:
support:
tier: Community
categories:
domains:
- Security - Threat Protection
author:
name: Yuval Naor
source:
kind: Community
{
"$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/f8b3c49c-4087-499b-920f-0dcfaff0cbca')]",
"kind": "Scheduled",
"name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/f8b3c49c-4087-499b-920f-0dcfaff0cbca')]",
"properties": {
"alertRuleTemplateName": "f8b3c49c-4087-499b-920f-0dcfaff0cbca",
"customDetails": null,
"description": "'Identifies instances of a base64 encoded PE file header seen in the process command line parameter.\nTo use this analytics rule, make sure you have deployed the [ASIM normalization parsers](https://aka.ms/ASimProcessEvent)'\n",
"displayName": "Base64 encoded Windows process command-lines (Normalized Process Events)",
"enabled": true,
"entityMappings": [
{
"entityType": "Account",
"fieldMappings": [
{
"columnName": "ActorUsername",
"identifier": "FullName"
},
{
"columnName": "AccountName",
"identifier": "Name"
},
{
"columnName": "AccountNTDomain",
"identifier": "NTDomain"
}
]
},
{
"entityType": "Host",
"fieldMappings": [
{
"columnName": "Dvc",
"identifier": "FullName"
},
{
"columnName": "HostName",
"identifier": "HostName"
},
{
"columnName": "HostNameDomain",
"identifier": "DnsDomain"
}
]
}
],
"OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/ASimProcess/imProcess_base64_encoded_pefile.yaml",
"query": "imProcessCreate\n| where CommandLine contains \"TVqQAAMAAAAEAAA\"\n| where isnotempty(Process)\n| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated), count() by Dvc, ActorUsername, Process, CommandLine, ActingProcessName, EventVendor, EventProduct\n| extend AccountName = tostring(split(ActorUsername, @'\\')[1]), AccountNTDomain = tostring(split(ActorUsername, @'\\')[0])\n| extend HostName = tostring(split(Dvc, \".\")[0]), DomainIndex = toint(indexof(Dvc, '.'))\n| extend HostNameDomain = iff(DomainIndex != -1, substring(Dvc, DomainIndex + 1), Dvc)\n| project-away DomainIndex\n",
"queryFrequency": "P1D",
"queryPeriod": "P1D",
"severity": "Medium",
"subTechniques": [],
"suppressionDuration": "PT1H",
"suppressionEnabled": false,
"tactics": [
"DefenseEvasion",
"Execution"
],
"tags": [
{
"Id": "ca67c83e-7fff-4127-a3e3-1af66d6d4cad",
"version": "1.0.0"
},
{
"Schema": "ASIMProcessEvent",
"SchemaVersion": "0.1.0"
}
],
"techniques": [
"T1027",
"T1059",
"T1140"
],
"templateVersion": "1.1.4",
"triggerOperator": "GreaterThan",
"triggerThreshold": 0
},
"type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
}
]
}