Detect DNS queries reporting multiple errors from different clients - Static threshold based ASIM DNS Solution
| Id | 5b8344eb-fa28-4ac3-bcff-bc19d5d63089 |
| Rulename | Detect DNS queries reporting multiple errors from different clients - Static threshold based (ASIM DNS Solution) |
| Description | This rule creates an alert when multiple clients report errors for the same DNS query. This helps in identifying possible similar C2 communications originating from different clients. It utilizes ASIM normalization and is applied to any source that supports the ASIM DNS schema. |
| Severity | Medium |
| Tactics | CommandAndControl |
| Techniques | T1568 T1573 T1008 |
| Kind | Scheduled |
| Query frequency | 1h |
| Query period | 1h |
| Trigger threshold | 0 |
| Trigger operator | gt |
| Source Uri | https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/DNS Essentials/Analytic Rules/MultipleErrorsReportedForSameDNSQueryStaticThresholdBased.yaml |
| Version | 1.0.4 |
| Arm template | 5b8344eb-fa28-4ac3-bcff-bc19d5d63089.json |
let lookback=1h;
let threshold = 2;
let errors = dynamic(['NXDOMAIN', 'SERVFAIL', 'REFUSED']);
_Im_Dns(starttime=ago(lookback))
| where EventResultDetails has_any (errors)
| summarize SrcIPs = make_set(SrcIpAddr, 100), Dvcs = make_set(Dvc, 100), ResourceIds = make_set(_ResourceId, 100) by DnsQuery, bin(TimeGenerated, 10min)
| where array_length(SrcIPs) >= threshold
| extend TotalIPs = array_length(SrcIPs),IPCountthreshold = threshold
| extend DomainName = strcat(split(DnsQuery, ".")[1], ".", split(DnsQuery, ".")[2])
| mv-expand SrcIPs
| extend SrcIP = tostring(SrcIPs)
| mv-expand Dvcs
| extend Dvc = tostring(Dvcs)
| mv-expand ResourceIds
| extend ResourceId = tostring(ResourceIds)
| extend Dvc = strcat(split(Dvc, ".")[0])
| summarize Start=min(TimeGenerated), End=max(TimeGenerated) by SrcIP, Dvc, ResourceId, DnsQuery, DomainName, SrcIPs = tostring(SrcIPs), IPCountthreshold = threshold, TotalIPs
| extend HostName = tostring(split(Dvc, ".")[0]), DomainIndex = toint(indexof(Dvc, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Dvc, DomainIndex + 1), Dvc)
tactics:
- CommandAndControl
alertDetailsOverride:
alertDisplayNameFormat: "[Static threshold] Multiple errors for the same DNS query has been detected - '{{DnsQuery}}'"
alertDescriptionFormat: |-
Multiple errors were detected on different clients for the same DNS query. These unsuccessful responses can be an indication of C2 communication.
Threshold for total clients reporting errors: '{{IPCountthreshold}}'
Current count of clients reporting errors for this DNS query: '{{TotalIPs}}'
Clients requesting this DNSQuery include:
'{{SrcIPs}}'
requiredDataConnectors: []
severity: Medium
queryFrequency: 1h
id: 5b8344eb-fa28-4ac3-bcff-bc19d5d63089
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/DNS Essentials/Analytic Rules/MultipleErrorsReportedForSameDNSQueryStaticThresholdBased.yaml
relevantTechniques:
- T1568
- T1573
- T1008
queryPeriod: 1h
tags:
- Schema: ASimDns
SchemaVersion: 0.1.6
status: Available
kind: Scheduled
triggerThreshold: 0
triggerOperator: gt
version: 1.0.4
entityMappings:
- entityType: DNS
fieldMappings:
- columnName: DnsQuery
identifier: DomainName
- entityType: IP
fieldMappings:
- columnName: SrcIP
identifier: Address
- entityType: AzureResource
fieldMappings:
- columnName: ResourceId
identifier: ResourceId
- entityType: Url
fieldMappings:
- columnName: DnsQuery
identifier: Url
- entityType: Host
fieldMappings:
- columnName: HostName
identifier: HostName
- columnName: HostNameDomain
identifier: NTDomain
eventGroupingSettings:
aggregationKind: SingleAlert
customDetails:
IPCountthreshold: IPCountthreshold
SrcIPs: SrcIPs
TotalIPs: TotalIPs
description: |
'This rule creates an alert when multiple clients report errors for the same DNS query. This helps in identifying possible similar C2 communications originating from different clients. It utilizes [ASIM](https://aka.ms/AboutASIM) normalization and is applied to any source that supports the ASIM DNS schema.'
name: Detect DNS queries reporting multiple errors from different clients - Static threshold based (ASIM DNS Solution)
query: |
let lookback=1h;
let threshold = 2;
let errors = dynamic(['NXDOMAIN', 'SERVFAIL', 'REFUSED']);
_Im_Dns(starttime=ago(lookback))
| where EventResultDetails has_any (errors)
| summarize SrcIPs = make_set(SrcIpAddr, 100), Dvcs = make_set(Dvc, 100), ResourceIds = make_set(_ResourceId, 100) by DnsQuery, bin(TimeGenerated, 10min)
| where array_length(SrcIPs) >= threshold
| extend TotalIPs = array_length(SrcIPs),IPCountthreshold = threshold
| extend DomainName = strcat(split(DnsQuery, ".")[1], ".", split(DnsQuery, ".")[2])
| mv-expand SrcIPs
| extend SrcIP = tostring(SrcIPs)
| mv-expand Dvcs
| extend Dvc = tostring(Dvcs)
| mv-expand ResourceIds
| extend ResourceId = tostring(ResourceIds)
| extend Dvc = strcat(split(Dvc, ".")[0])
| summarize Start=min(TimeGenerated), End=max(TimeGenerated) by SrcIP, Dvc, ResourceId, DnsQuery, DomainName, SrcIPs = tostring(SrcIPs), IPCountthreshold = threshold, TotalIPs
| extend HostName = tostring(split(Dvc, ".")[0]), DomainIndex = toint(indexof(Dvc, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Dvc, DomainIndex + 1), Dvc)
{
"$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/5b8344eb-fa28-4ac3-bcff-bc19d5d63089')]",
"kind": "Scheduled",
"name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/5b8344eb-fa28-4ac3-bcff-bc19d5d63089')]",
"properties": {
"alertDetailsOverride": {
"alertDescriptionFormat": "Multiple errors were detected on different clients for the same DNS query. These unsuccessful responses can be an indication of C2 communication. \n\nThreshold for total clients reporting errors: '{{IPCountthreshold}}'\n\nCurrent count of clients reporting errors for this DNS query: '{{TotalIPs}}'\n\nClients requesting this DNSQuery include:\n\n'{{SrcIPs}}'",
"alertDisplayNameFormat": "[Static threshold] Multiple errors for the same DNS query has been detected - '{{DnsQuery}}'"
},
"alertRuleTemplateName": "5b8344eb-fa28-4ac3-bcff-bc19d5d63089",
"customDetails": {
"IPCountthreshold": "IPCountthreshold",
"SrcIPs": "SrcIPs",
"TotalIPs": "TotalIPs"
},
"description": "'This rule creates an alert when multiple clients report errors for the same DNS query. This helps in identifying possible similar C2 communications originating from different clients. It utilizes [ASIM](https://aka.ms/AboutASIM) normalization and is applied to any source that supports the ASIM DNS schema.'\n",
"displayName": "Detect DNS queries reporting multiple errors from different clients - Static threshold based (ASIM DNS Solution)",
"enabled": true,
"entityMappings": [
{
"entityType": "DNS",
"fieldMappings": [
{
"columnName": "DnsQuery",
"identifier": "DomainName"
}
]
},
{
"entityType": "IP",
"fieldMappings": [
{
"columnName": "SrcIP",
"identifier": "Address"
}
]
},
{
"entityType": "AzureResource",
"fieldMappings": [
{
"columnName": "ResourceId",
"identifier": "ResourceId"
}
]
},
{
"entityType": "Url",
"fieldMappings": [
{
"columnName": "DnsQuery",
"identifier": "Url"
}
]
},
{
"entityType": "Host",
"fieldMappings": [
{
"columnName": "HostName",
"identifier": "HostName"
},
{
"columnName": "HostNameDomain",
"identifier": "NTDomain"
}
]
}
],
"eventGroupingSettings": {
"aggregationKind": "SingleAlert"
},
"OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/DNS Essentials/Analytic Rules/MultipleErrorsReportedForSameDNSQueryStaticThresholdBased.yaml",
"query": "let lookback=1h;\nlet threshold = 2;\nlet errors = dynamic(['NXDOMAIN', 'SERVFAIL', 'REFUSED']); \n_Im_Dns(starttime=ago(lookback)) \n | where EventResultDetails has_any (errors) \n | summarize SrcIPs = make_set(SrcIpAddr, 100), Dvcs = make_set(Dvc, 100), ResourceIds = make_set(_ResourceId, 100) by DnsQuery, bin(TimeGenerated, 10min) \n | where array_length(SrcIPs) >= threshold \n | extend TotalIPs = array_length(SrcIPs),IPCountthreshold = threshold \n | extend DomainName = strcat(split(DnsQuery, \".\")[1], \".\", split(DnsQuery, \".\")[2]) \n | mv-expand SrcIPs \n | extend SrcIP = tostring(SrcIPs) \n | mv-expand Dvcs \n | extend Dvc = tostring(Dvcs) \n | mv-expand ResourceIds \n | extend ResourceId = tostring(ResourceIds) \n | extend Dvc = strcat(split(Dvc, \".\")[0])\n | summarize Start=min(TimeGenerated), End=max(TimeGenerated) by SrcIP, Dvc, ResourceId, DnsQuery, DomainName, SrcIPs = tostring(SrcIPs), IPCountthreshold = threshold, TotalIPs\n | extend HostName = tostring(split(Dvc, \".\")[0]), DomainIndex = toint(indexof(Dvc, '.'))\n | extend HostNameDomain = iff(DomainIndex != -1, substring(Dvc, DomainIndex + 1), Dvc)\n",
"queryFrequency": "PT1H",
"queryPeriod": "PT1H",
"severity": "Medium",
"status": "Available",
"subTechniques": [],
"suppressionDuration": "PT1H",
"suppressionEnabled": false,
"tactics": [
"CommandAndControl"
],
"tags": [
{
"Schema": "ASimDns",
"SchemaVersion": "0.1.6"
}
],
"techniques": [
"T1008",
"T1568",
"T1573"
],
"templateVersion": "1.0.4",
"triggerOperator": "GreaterThan",
"triggerThreshold": 0
},
"type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
}
]
}