Detect known risky user agents ASIM Web Session
| Id | 6a4dbcf8-f5e2-4b33-b34f-2db6487613f0 |
| Rulename | Detect known risky user agents (ASIM Web Session) |
| Description | This rule is designed to flag web requests that contain a user agent header that is recognized as malicious. It relies on a predefined list of known user agents, which is referenced from a specific CSV file |
| Severity | Medium |
| Tactics | InitialAccess CommandAndControl |
| Techniques | T1190 T1133 T1071 |
| Kind | Scheduled |
| Query frequency | 5m |
| Query period | 5m |
| Trigger threshold | 0 |
| Trigger operator | gt |
| Source Uri | https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Web Session Essentials/Analytic Rules/KnownMaliciousUserAgents.yaml |
| Version | 1.0.0 |
| Arm template | 6a4dbcf8-f5e2-4b33-b34f-2db6487613f0.json |
let lookback = 5m;
let knownUserAgentsIndicators = materialize(externaldata(UserAgent: string, UserAgentCategory: string)
[@"https://raw.githubusercontent.com/Azure/Azure-Sentinel/master/Sample%20Data/Feeds/UnusualUserAgents.csv"]
with(format="csv", ignoreFirstRecord=True)
| extend joiner = 1);
let CustomUserAgentIndicators = (_ASIM_GetWatchlistRaw("UnusualUserAgents") // Create new Watchlist and add your custom indicators(Optional)
| extend
UserAgent = tostring(WatchlistItem["UserAgent"]),
UserAgentCategory = tostring(WatchlistItem["UserAgentCategory"])
| project UserAgent, UserAgentCategory, joiner = 1
| where isnotempty(UserAgent) and isnotempty(UserAgentCategory));
let CombinedUAList = union knownUserAgentsIndicators, CustomUserAgentIndicators;
let knownUserAgents=toscalar(CombinedUAList
| where isnotempty(UserAgent)
| summarize make_list(UserAgent, 1000));
_Im_WebSession (starttime=ago(lookback), httpuseragent_has_any=knownUserAgents)
| project SrcIpAddr, SrcUsername, SrcHostname, HttpUserAgent, Url, DstIpAddr, DstPortNumber, TimeGenerated
| extend joiner = 1
| join kind=inner CombinedUAList on joiner
| where HttpUserAgent has UserAgent
| summarize
EventCount=count(),
EventStartTime = min(TimeGenerated),
EventEndTime=max(TimeGenerated)
by SrcIpAddr, SrcUsername, SrcHostname, Url, HttpUserAgent, DstIpAddr, DstPortNumber, UserAgentCategory
| extend Name = iif(SrcUsername contains "@", tostring(split(SrcUsername,'@',0)[0]),SrcUsername), UPNSuffix = iif(SrcUsername contains "@",tostring(split(SrcUsername,'@',1)[0]),"")
relevantTechniques:
- T1190
- T1133
- T1071
name: Detect known risky user agents (ASIM Web Session)
requiredDataConnectors: []
entityMappings:
- fieldMappings:
- identifier: Url
columnName: Url
entityType: URL
- fieldMappings:
- identifier: Address
columnName: SrcIpAddr
entityType: IP
- fieldMappings:
- identifier: Address
columnName: DstIpAddr
entityType: IP
- fieldMappings:
- identifier: Name
columnName: Name
- identifier: UPNSuffix
columnName: UPNSuffix
entityType: Account
- fieldMappings:
- identifier: HostName
columnName: SrcHostname
entityType: Host
triggerThreshold: 0
id: 6a4dbcf8-f5e2-4b33-b34f-2db6487613f0
tactics:
- InitialAccess
- CommandAndControl
version: 1.0.0
customDetails:
HttpUserAgent: HttpUserAgent
EventCount: EventCount
EventEndTime: EventEndTime
EventStartTime: EventStartTime
UserAgentCategory: UserAgentCategory
queryPeriod: 5m
alertDetailsOverride:
alertDisplayNameFormat: User '{{SrcUsername}}' with IP '{{SrcIpAddr}}' has been observed using User Agent categorized as '{{UserAgentCategory}}'
alertDescriptionFormat: User accessed this URL '{{Url}}' using User Agent '{{HttpUserAgent}}'. Perform a thorough analysis of the requests associated with this user agent header
triggerOperator: gt
kind: Scheduled
tags:
- Schema: WebSession
SchemaVersion: 0.2.6
eventGroupingSettings:
aggregationKind: AlertPerResult
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Web Session Essentials/Analytic Rules/KnownMaliciousUserAgents.yaml
queryFrequency: 5m
severity: Medium
status: Available
description: |
'This rule is designed to flag web requests that contain a user agent header that is recognized as malicious. It relies on a predefined list of known user agents, which is referenced from a specific CSV file'
query: |
let lookback = 5m;
let knownUserAgentsIndicators = materialize(externaldata(UserAgent: string, UserAgentCategory: string)
[@"https://raw.githubusercontent.com/Azure/Azure-Sentinel/master/Sample%20Data/Feeds/UnusualUserAgents.csv"]
with(format="csv", ignoreFirstRecord=True)
| extend joiner = 1);
let CustomUserAgentIndicators = (_ASIM_GetWatchlistRaw("UnusualUserAgents") // Create new Watchlist and add your custom indicators(Optional)
| extend
UserAgent = tostring(WatchlistItem["UserAgent"]),
UserAgentCategory = tostring(WatchlistItem["UserAgentCategory"])
| project UserAgent, UserAgentCategory, joiner = 1
| where isnotempty(UserAgent) and isnotempty(UserAgentCategory));
let CombinedUAList = union knownUserAgentsIndicators, CustomUserAgentIndicators;
let knownUserAgents=toscalar(CombinedUAList
| where isnotempty(UserAgent)
| summarize make_list(UserAgent, 1000));
_Im_WebSession (starttime=ago(lookback), httpuseragent_has_any=knownUserAgents)
| project SrcIpAddr, SrcUsername, SrcHostname, HttpUserAgent, Url, DstIpAddr, DstPortNumber, TimeGenerated
| extend joiner = 1
| join kind=inner CombinedUAList on joiner
| where HttpUserAgent has UserAgent
| summarize
EventCount=count(),
EventStartTime = min(TimeGenerated),
EventEndTime=max(TimeGenerated)
by SrcIpAddr, SrcUsername, SrcHostname, Url, HttpUserAgent, DstIpAddr, DstPortNumber, UserAgentCategory
| extend Name = iif(SrcUsername contains "@", tostring(split(SrcUsername,'@',0)[0]),SrcUsername), UPNSuffix = iif(SrcUsername contains "@",tostring(split(SrcUsername,'@',1)[0]),"")
{
"$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/6a4dbcf8-f5e2-4b33-b34f-2db6487613f0')]",
"kind": "Scheduled",
"name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/6a4dbcf8-f5e2-4b33-b34f-2db6487613f0')]",
"properties": {
"alertDetailsOverride": {
"alertDescriptionFormat": "User accessed this URL '{{Url}}' using User Agent '{{HttpUserAgent}}'. Perform a thorough analysis of the requests associated with this user agent header",
"alertDisplayNameFormat": "User '{{SrcUsername}}' with IP '{{SrcIpAddr}}' has been observed using User Agent categorized as '{{UserAgentCategory}}'"
},
"alertRuleTemplateName": "6a4dbcf8-f5e2-4b33-b34f-2db6487613f0",
"customDetails": {
"EventCount": "EventCount",
"EventEndTime": "EventEndTime",
"EventStartTime": "EventStartTime",
"HttpUserAgent": "HttpUserAgent",
"UserAgentCategory": "UserAgentCategory"
},
"description": "'This rule is designed to flag web requests that contain a user agent header that is recognized as malicious. It relies on a predefined list of known user agents, which is referenced from a specific CSV file'\n",
"displayName": "Detect known risky user agents (ASIM Web Session)",
"enabled": true,
"entityMappings": [
{
"entityType": "URL",
"fieldMappings": [
{
"columnName": "Url",
"identifier": "Url"
}
]
},
{
"entityType": "IP",
"fieldMappings": [
{
"columnName": "SrcIpAddr",
"identifier": "Address"
}
]
},
{
"entityType": "IP",
"fieldMappings": [
{
"columnName": "DstIpAddr",
"identifier": "Address"
}
]
},
{
"entityType": "Account",
"fieldMappings": [
{
"columnName": "Name",
"identifier": "Name"
},
{
"columnName": "UPNSuffix",
"identifier": "UPNSuffix"
}
]
},
{
"entityType": "Host",
"fieldMappings": [
{
"columnName": "SrcHostname",
"identifier": "HostName"
}
]
}
],
"eventGroupingSettings": {
"aggregationKind": "AlertPerResult"
},
"OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Web Session Essentials/Analytic Rules/KnownMaliciousUserAgents.yaml",
"query": "let lookback = 5m;\nlet knownUserAgentsIndicators = materialize(externaldata(UserAgent: string, UserAgentCategory: string)\n [@\"https://raw.githubusercontent.com/Azure/Azure-Sentinel/master/Sample%20Data/Feeds/UnusualUserAgents.csv\"] \n with(format=\"csv\", ignoreFirstRecord=True)\n | extend joiner = 1);\nlet CustomUserAgentIndicators = (_ASIM_GetWatchlistRaw(\"UnusualUserAgents\") // Create new Watchlist and add your custom indicators(Optional)\n | extend\n UserAgent = tostring(WatchlistItem[\"UserAgent\"]),\n UserAgentCategory = tostring(WatchlistItem[\"UserAgentCategory\"])\n | project UserAgent, UserAgentCategory, joiner = 1\n | where isnotempty(UserAgent) and isnotempty(UserAgentCategory));\nlet CombinedUAList = union knownUserAgentsIndicators, CustomUserAgentIndicators;\nlet knownUserAgents=toscalar(CombinedUAList\n | where isnotempty(UserAgent)\n | summarize make_list(UserAgent, 1000));\n_Im_WebSession (starttime=ago(lookback), httpuseragent_has_any=knownUserAgents)\n| project SrcIpAddr, SrcUsername, SrcHostname, HttpUserAgent, Url, DstIpAddr, DstPortNumber, TimeGenerated\n| extend joiner = 1\n| join kind=inner CombinedUAList on joiner\n| where HttpUserAgent has UserAgent\n| summarize\n EventCount=count(),\n EventStartTime = min(TimeGenerated),\n EventEndTime=max(TimeGenerated)\n by SrcIpAddr, SrcUsername, SrcHostname, Url, HttpUserAgent, DstIpAddr, DstPortNumber, UserAgentCategory\n| extend Name = iif(SrcUsername contains \"@\", tostring(split(SrcUsername,'@',0)[0]),SrcUsername), UPNSuffix = iif(SrcUsername contains \"@\",tostring(split(SrcUsername,'@',1)[0]),\"\")\n",
"queryFrequency": "PT5M",
"queryPeriod": "PT5M",
"severity": "Medium",
"status": "Available",
"subTechniques": [],
"suppressionDuration": "PT1H",
"suppressionEnabled": false,
"tactics": [
"CommandAndControl",
"InitialAccess"
],
"tags": [
{
"Schema": "WebSession",
"SchemaVersion": "0.2.6"
}
],
"techniques": [
"T1071",
"T1133",
"T1190"
],
"templateVersion": "1.0.0",
"triggerOperator": "GreaterThan",
"triggerThreshold": 0
},
"type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
}
]
}