Windows host username encoded in base64 web request
Id | 6e715730-82c0-496c-983b-7a20c4590bd9 |
Rulename | Windows host username encoded in base64 web request |
Description | This detection will identify network requests in HTTP proxy data that contains Base64 encoded usernames from machines in the DeviceEvents table. This technique was seen usee by POLONIUM in their RunningRAT tool. |
Severity | Medium |
Tactics | Exfiltration CommandAndControl |
Techniques | T1041 T1071.001 |
Required data connectors | CheckPoint Fortinet MicrosoftThreatProtection PaloAltoNetworks Zscaler |
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/MultipleDataSources/B64UserInWebURIFromMDE.yaml |
Version | 1.0.1 |
Arm template | 6e715730-82c0-496c-983b-7a20c4590bd9.json |
let accountLookback = 3d;
let requestLookback = 3d;
let extraction_regex = @"(?:\?|&)[a-zA-Z0-9\%]*=([a-zA-Z0-9\/\+\=]*)";
// Collect account names and base64 encode them
DeviceEvents
| where TimeGenerated > ago(accountLookback)
| summarize make_set(DeviceId), make_set(DeviceName) by InitiatingProcessAccountName
| where isnotempty(InitiatingProcessAccountName)
| extend base64_user = base64_encode_tostring(InitiatingProcessAccountName)
| join (
// Collect requests and extract base64 parameters
CommonSecurityLog
| where TimeGenerated > ago(requestLookback)
| where isnotempty(RequestURL)
// Summarize early on the RequestURL
| summarize FirstRequest=min(TimeGenerated), LastRequest=max(TimeGenerated), NumberOfRequests=count() by RequestURL
| extend base64_candidate = extract_all(extraction_regex, RequestURL)
| mv-expand base64_candidate to typeof(string)
) on $left.base64_user == $right.base64_candidate
| project FirstRequest, LastRequest, NumberOfRequests, RequestURL, DeviceIds=set_DeviceId, DeviceNames=set_DeviceName, UserName=InitiatingProcessAccountName
queryPeriod: 1d
name: Windows host username encoded in base64 web request
description: |
'This detection will identify network requests in HTTP proxy data that contains Base64 encoded usernames from machines in the DeviceEvents table.
This technique was seen usee by POLONIUM in their RunningRAT tool.'
requiredDataConnectors:
- dataTypes:
- CommonSecurityLog
connectorId: Zscaler
- dataTypes:
- CommonSecurityLog
connectorId: Fortinet
- dataTypes:
- CommonSecurityLog
connectorId: CheckPoint
- dataTypes:
- CommonSecurityLog
connectorId: PaloAltoNetworks
- dataTypes:
- DeviceNetworkEvents
connectorId: MicrosoftThreatProtection
kind: Scheduled
id: 6e715730-82c0-496c-983b-7a20c4590bd9
version: 1.0.1
triggerOperator: gt
triggerThreshold: 0
query: |
let accountLookback = 3d;
let requestLookback = 3d;
let extraction_regex = @"(?:\?|&)[a-zA-Z0-9\%]*=([a-zA-Z0-9\/\+\=]*)";
// Collect account names and base64 encode them
DeviceEvents
| where TimeGenerated > ago(accountLookback)
| summarize make_set(DeviceId), make_set(DeviceName) by InitiatingProcessAccountName
| where isnotempty(InitiatingProcessAccountName)
| extend base64_user = base64_encode_tostring(InitiatingProcessAccountName)
| join (
// Collect requests and extract base64 parameters
CommonSecurityLog
| where TimeGenerated > ago(requestLookback)
| where isnotempty(RequestURL)
// Summarize early on the RequestURL
| summarize FirstRequest=min(TimeGenerated), LastRequest=max(TimeGenerated), NumberOfRequests=count() by RequestURL
| extend base64_candidate = extract_all(extraction_regex, RequestURL)
| mv-expand base64_candidate to typeof(string)
) on $left.base64_user == $right.base64_candidate
| project FirstRequest, LastRequest, NumberOfRequests, RequestURL, DeviceIds=set_DeviceId, DeviceNames=set_DeviceName, UserName=InitiatingProcessAccountName
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/MultipleDataSources/B64UserInWebURIFromMDE.yaml
entityMappings:
- fieldMappings:
- identifier: HostName
columnName: DeviceNames
entityType: Host
- fieldMappings:
- identifier: Url
columnName: RequestURL
entityType: URL
- fieldMappings:
- identifier: Name
columnName: UserName
entityType: Account
metadata:
author:
name: Thomas McElroy
support:
tier: Community
categories:
domains:
- Security - Others
source:
kind: Community
tactics:
- Exfiltration
- CommandAndControl
relevantTechniques:
- T1041
- T1071.001
queryFrequency: 1d
severity: Medium
tags:
- POLONIUM
{
"$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/6e715730-82c0-496c-983b-7a20c4590bd9')]",
"kind": "Scheduled",
"name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/6e715730-82c0-496c-983b-7a20c4590bd9')]",
"properties": {
"alertRuleTemplateName": "6e715730-82c0-496c-983b-7a20c4590bd9",
"customDetails": null,
"description": "'This detection will identify network requests in HTTP proxy data that contains Base64 encoded usernames from machines in the DeviceEvents table.\nThis technique was seen usee by POLONIUM in their RunningRAT tool.'\n",
"displayName": "Windows host username encoded in base64 web request",
"enabled": true,
"entityMappings": [
{
"entityType": "Host",
"fieldMappings": [
{
"columnName": "DeviceNames",
"identifier": "HostName"
}
]
},
{
"entityType": "URL",
"fieldMappings": [
{
"columnName": "RequestURL",
"identifier": "Url"
}
]
},
{
"entityType": "Account",
"fieldMappings": [
{
"columnName": "UserName",
"identifier": "Name"
}
]
}
],
"OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/MultipleDataSources/B64UserInWebURIFromMDE.yaml",
"query": "let accountLookback = 3d;\nlet requestLookback = 3d;\nlet extraction_regex = @\"(?:\\?|&)[a-zA-Z0-9\\%]*=([a-zA-Z0-9\\/\\+\\=]*)\";\n// Collect account names and base64 encode them\nDeviceEvents\n| where TimeGenerated > ago(accountLookback)\n| summarize make_set(DeviceId), make_set(DeviceName) by InitiatingProcessAccountName\n| where isnotempty(InitiatingProcessAccountName)\n| extend base64_user = base64_encode_tostring(InitiatingProcessAccountName)\n| join (\n // Collect requests and extract base64 parameters\n CommonSecurityLog\n | where TimeGenerated > ago(requestLookback)\n | where isnotempty(RequestURL)\n // Summarize early on the RequestURL\n | summarize FirstRequest=min(TimeGenerated), LastRequest=max(TimeGenerated), NumberOfRequests=count() by RequestURL\n | extend base64_candidate = extract_all(extraction_regex, RequestURL)\n | mv-expand base64_candidate to typeof(string)\n) on $left.base64_user == $right.base64_candidate\n| project FirstRequest, LastRequest, NumberOfRequests, RequestURL, DeviceIds=set_DeviceId, DeviceNames=set_DeviceName, UserName=InitiatingProcessAccountName\n",
"queryFrequency": "P1D",
"queryPeriod": "P1D",
"severity": "Medium",
"subTechniques": [
"T1071.001"
],
"suppressionDuration": "PT1H",
"suppressionEnabled": false,
"tactics": [
"CommandAndControl",
"Exfiltration"
],
"tags": [
"POLONIUM"
],
"techniques": [
"T1041",
"T1071"
],
"templateVersion": "1.0.1",
"triggerOperator": "GreaterThan",
"triggerThreshold": 0
},
"type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
}
]
}