Malformed user agent
Id | a357535e-f722-4afe-b375-cff362b2b376 |
Rulename | Malformed user agent |
Description | Malware authors will sometimes hardcode user agent string values when writing the network communication component of their malware. Malformed user agents can be an indication of such malware. |
Severity | Medium |
Tactics | InitialAccess CommandAndControl Execution |
Techniques | T1189 T1071 T1203 |
Required data connectors | AWS AzureActiveDirectory AzureMonitor(IIS) Office365 WAF |
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/MalformedUserAgents.yaml |
Version | 1.0.2 |
Arm template | a357535e-f722-4afe-b375-cff362b2b376.json |
(union isfuzzy=true
(OfficeActivity | where UserAgent != ""),
(OfficeActivity
| where RecordType in ("AzureActiveDirectory", "AzureActiveDirectoryStsLogon")
| extend OperationName = Operation
| parse ExtendedProperties with * 'User-Agent\\":\\"' UserAgent2 '\\' *
| parse ExtendedProperties with * 'UserAgent", "Value": "' UserAgent1 '"' *
| where isnotempty(UserAgent1) or isnotempty(UserAgent2)
| extend UserAgent = iff( RecordType == 'AzureActiveDirectoryStsLogon', UserAgent1, UserAgent2)
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = ClientIP, Account = UserId, Type, RecordType, Operation
),
(AzureDiagnostics
| where ResourceType =~ "APPLICATIONGATEWAYS"
| where OperationName =~ "ApplicationGatewayAccess"
| extend ClientIP = columnifexists("clientIP_s", "None"), UserAgent = columnifexists("userAgent_s", "None")
| where UserAgent != '-'
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = ClientIP, requestUri_s, httpMethod_s, host_s, requestQuery_s, Type
),
(
W3CIISLog
| where isnotempty(csUserAgent)
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent = csUserAgent, SourceIP = cIP, Account = csUserName, Type, sSiteName, csMethod, csUriStem
),
(
AWSCloudTrail
| where isnotempty(UserAgent)
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = SourceIpAddress, Account = UserIdentityUserName, Type, EventSource, EventName
),
(SigninLogs
| where isnotempty(UserAgent)
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = IPAddress, Account = UserPrincipalName, Type, OperationName, tostring(LocationDetails), tostring(DeviceDetail), AppDisplayName, ClientAppUsed
),
(AADNonInteractiveUserSignInLogs
| where isnotempty(UserAgent)
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = IPAddress, Account = UserPrincipalName, Type, OperationName, tostring(LocationDetails), tostring(DeviceDetail), AppDisplayName, ClientAppUsed
)
)
// Likely artefact of hardcoding
| where UserAgent startswith "User" or UserAgent startswith '\"'
// Incorrect casing
or (UserAgent startswith "Mozilla" and not(UserAgent containscs "Mozilla"))
// Incorrect casing
or UserAgent containscs "(Compatible;"
// Missing MSIE version
or UserAgent matches regex @"MSIE\s?;"
// Incorrect spacing around MSIE version
or UserAgent matches regex @"MSIE(?:\d|.{1,5}?\d\s;)"
| extend timestamp = StartTime, IPCustomEntity = SourceIP, AccountCustomEntity = Account
queryPeriod: 1d
version: 1.0.2
relevantTechniques:
- T1189
- T1071
- T1203
queryFrequency: 1d
kind: Scheduled
severity: Medium
name: Malformed user agent
id: a357535e-f722-4afe-b375-cff362b2b376
entityMappings:
- fieldMappings:
- columnName: AccountCustomEntity
identifier: FullName
entityType: Account
- fieldMappings:
- columnName: IPCustomEntity
identifier: Address
entityType: IP
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/MultipleDataSources/MalformedUserAgents.yaml
query: |
(union isfuzzy=true
(OfficeActivity | where UserAgent != ""),
(OfficeActivity
| where RecordType in ("AzureActiveDirectory", "AzureActiveDirectoryStsLogon")
| extend OperationName = Operation
| parse ExtendedProperties with * 'User-Agent\\":\\"' UserAgent2 '\\' *
| parse ExtendedProperties with * 'UserAgent", "Value": "' UserAgent1 '"' *
| where isnotempty(UserAgent1) or isnotempty(UserAgent2)
| extend UserAgent = iff( RecordType == 'AzureActiveDirectoryStsLogon', UserAgent1, UserAgent2)
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = ClientIP, Account = UserId, Type, RecordType, Operation
),
(AzureDiagnostics
| where ResourceType =~ "APPLICATIONGATEWAYS"
| where OperationName =~ "ApplicationGatewayAccess"
| extend ClientIP = columnifexists("clientIP_s", "None"), UserAgent = columnifexists("userAgent_s", "None")
| where UserAgent != '-'
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = ClientIP, requestUri_s, httpMethod_s, host_s, requestQuery_s, Type
),
(
W3CIISLog
| where isnotempty(csUserAgent)
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent = csUserAgent, SourceIP = cIP, Account = csUserName, Type, sSiteName, csMethod, csUriStem
),
(
AWSCloudTrail
| where isnotempty(UserAgent)
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = SourceIpAddress, Account = UserIdentityUserName, Type, EventSource, EventName
),
(SigninLogs
| where isnotempty(UserAgent)
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = IPAddress, Account = UserPrincipalName, Type, OperationName, tostring(LocationDetails), tostring(DeviceDetail), AppDisplayName, ClientAppUsed
),
(AADNonInteractiveUserSignInLogs
| where isnotempty(UserAgent)
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = IPAddress, Account = UserPrincipalName, Type, OperationName, tostring(LocationDetails), tostring(DeviceDetail), AppDisplayName, ClientAppUsed
)
)
// Likely artefact of hardcoding
| where UserAgent startswith "User" or UserAgent startswith '\"'
// Incorrect casing
or (UserAgent startswith "Mozilla" and not(UserAgent containscs "Mozilla"))
// Incorrect casing
or UserAgent containscs "(Compatible;"
// Missing MSIE version
or UserAgent matches regex @"MSIE\s?;"
// Incorrect spacing around MSIE version
or UserAgent matches regex @"MSIE(?:\d|.{1,5}?\d\s;)"
| extend timestamp = StartTime, IPCustomEntity = SourceIP, AccountCustomEntity = Account
tactics:
- InitialAccess
- CommandAndControl
- Execution
description: |
'Malware authors will sometimes hardcode user agent string values when writing the network communication component of their malware.
Malformed user agents can be an indication of such malware.'
requiredDataConnectors:
- connectorId: WAF
dataTypes:
- AzureDiagnostics
- connectorId: Office365
dataTypes:
- OfficeActivity
- connectorId: AzureActiveDirectory
dataTypes:
- SigninLogs
- connectorId: AzureActiveDirectory
dataTypes:
- AADNonInteractiveUserSignInLogs
- connectorId: AWS
dataTypes:
- AWSCloudTrail
- connectorId: AzureMonitor(IIS)
dataTypes:
- W3CIISLog
metadata:
author:
name: timbMSFT
source:
kind: Community
categories:
domains:
- Security - Threat Protection
support:
tier: Community
triggerThreshold: 0
triggerOperator: gt
{
"$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"workspace": {
"type": "String"
}
},
"resources": [
{
"id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/a357535e-f722-4afe-b375-cff362b2b376')]",
"name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/a357535e-f722-4afe-b375-cff362b2b376')]",
"type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
"kind": "Scheduled",
"apiVersion": "2022-11-01",
"properties": {
"displayName": "Malformed user agent",
"description": "'Malware authors will sometimes hardcode user agent string values when writing the network communication component of their malware.\nMalformed user agents can be an indication of such malware.'\n",
"severity": "Medium",
"enabled": true,
"query": "(union isfuzzy=true\n(OfficeActivity | where UserAgent != \"\"),\n(OfficeActivity\n| where RecordType in (\"AzureActiveDirectory\", \"AzureActiveDirectoryStsLogon\")\n| extend OperationName = Operation\n| parse ExtendedProperties with * 'User-Agent\\\\\":\\\\\"' UserAgent2 '\\\\' *\n| parse ExtendedProperties with * 'UserAgent\", \"Value\": \"' UserAgent1 '\"' *\n| where isnotempty(UserAgent1) or isnotempty(UserAgent2)\n| extend UserAgent = iff( RecordType == 'AzureActiveDirectoryStsLogon', UserAgent1, UserAgent2)\n| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = ClientIP, Account = UserId, Type, RecordType, Operation\n),\n(AzureDiagnostics\n| where ResourceType =~ \"APPLICATIONGATEWAYS\"\n| where OperationName =~ \"ApplicationGatewayAccess\"\n| extend ClientIP = columnifexists(\"clientIP_s\", \"None\"), UserAgent = columnifexists(\"userAgent_s\", \"None\")\n| where UserAgent != '-'\n| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = ClientIP, requestUri_s, httpMethod_s, host_s, requestQuery_s, Type\n),\n(\nW3CIISLog\n| where isnotempty(csUserAgent)\n| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent = csUserAgent, SourceIP = cIP, Account = csUserName, Type, sSiteName, csMethod, csUriStem\n),\n(\nAWSCloudTrail\n| where isnotempty(UserAgent)\n| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = SourceIpAddress, Account = UserIdentityUserName, Type, EventSource, EventName\n),\n(SigninLogs\n| where isnotempty(UserAgent)\n| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = IPAddress, Account = UserPrincipalName, Type, OperationName, tostring(LocationDetails), tostring(DeviceDetail), AppDisplayName, ClientAppUsed\n),\n(AADNonInteractiveUserSignInLogs\n| where isnotempty(UserAgent)\n| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = IPAddress, Account = UserPrincipalName, Type, OperationName, tostring(LocationDetails), tostring(DeviceDetail), AppDisplayName, ClientAppUsed\n)\n)\n// Likely artefact of hardcoding\n| where UserAgent startswith \"User\" or UserAgent startswith '\\\"'\n// Incorrect casing\nor (UserAgent startswith \"Mozilla\" and not(UserAgent containscs \"Mozilla\"))\n// Incorrect casing\nor UserAgent containscs \"(Compatible;\"\n// Missing MSIE version\nor UserAgent matches regex @\"MSIE\\s?;\"\n// Incorrect spacing around MSIE version\nor UserAgent matches regex @\"MSIE(?:\\d|.{1,5}?\\d\\s;)\"\n| extend timestamp = StartTime, IPCustomEntity = SourceIP, AccountCustomEntity = Account\n",
"queryFrequency": "P1D",
"queryPeriod": "P1D",
"triggerOperator": "GreaterThan",
"triggerThreshold": 0,
"suppressionDuration": "PT1H",
"suppressionEnabled": false,
"tactics": [
"InitialAccess",
"CommandAndControl",
"Execution"
],
"techniques": [
"T1189",
"T1071",
"T1203"
],
"alertRuleTemplateName": "a357535e-f722-4afe-b375-cff362b2b376",
"customDetails": null,
"entityMappings": [
{
"fieldMappings": [
{
"identifier": "FullName",
"columnName": "AccountCustomEntity"
}
],
"entityType": "Account"
},
{
"fieldMappings": [
{
"identifier": "Address",
"columnName": "IPCustomEntity"
}
],
"entityType": "IP"
}
],
"templateVersion": "1.0.2",
"OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/MultipleDataSources/MalformedUserAgents.yaml"
}
}
]
}