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
triggerOperator: gt
queryFrequency: 1d
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.'
version: 1.0.1
kind: Scheduled
triggerThreshold: 0
requiredDataConnectors:
- connectorId: Zscaler
dataTypes:
- CommonSecurityLog
- connectorId: Fortinet
dataTypes:
- CommonSecurityLog
- connectorId: CheckPoint
dataTypes:
- CommonSecurityLog
- connectorId: PaloAltoNetworks
dataTypes:
- CommonSecurityLog
- connectorId: MicrosoftThreatProtection
dataTypes:
- DeviceNetworkEvents
queryPeriod: 1d
name: Windows host username encoded in base64 web request
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/MultipleDataSources/B64UserInWebURIFromMDE.yaml
id: 6e715730-82c0-496c-983b-7a20c4590bd9
tags:
- POLONIUM
tactics:
- Exfiltration
- CommandAndControl
metadata:
source:
kind: Community
author:
name: Thomas McElroy
categories:
domains:
- Security - Others
support:
tier: Community
relevantTechniques:
- T1041
- T1071.001
severity: Medium
entityMappings:
- fieldMappings:
- identifier: HostName
columnName: DeviceNames
entityType: Host
- fieldMappings:
- identifier: Url
columnName: RequestURL
entityType: URL
- fieldMappings:
- identifier: Name
columnName: UserName
entityType: Account
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 == $right.base64_candidate
| project FirstRequest, LastRequest, NumberOfRequests, RequestURL, DeviceIds=set_DeviceId, DeviceNames=set_DeviceName, UserName=InitiatingProcessAccountName
{
"$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"workspace": {
"type": "String"
}
},
"resources": [
{
"apiVersion": "2023-02-01-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",
"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"
}
]
}