Detection rules › Kusto
TI map URL entity to Cloud App Events
'Identifies compromises and attacks and detect malicious activities in one's URL entity from TI'
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Command & Control | T1071 Application Layer Protocol |
Rule body kusto
id: 526df43b-f514-477c-af7a-c8d3586457fb
name: TI map URL entity to Cloud App Events
description: |
'Identifies compromises and attacks and detect malicious activities in one's URL entity from TI'
severity: Medium
requiredDataConnectors:
- connectorId: MicrosoftThreatProtection
dataTypes:
- CloudAppEvents
- connectorId: MicrosoftDefenderThreatIntelligence
dataTypes:
- ThreatIntelIndicators
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
- CommandAndControl
relevantTechniques:
- T1071
query: |
let dt_lookBack = 1h;
let ioc_lookBack = 14d;
ThreatIntelIndicators
//extract key part of kv pair
| extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
| where IndicatorType == "url"
| extend Url = ObservableValue
| extend IndicatorId = tostring(split(Id, "--")[2])
| where TimeGenerated >= ago(ioc_lookBack)
| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId, ObservableValue
| where IsActive and (ValidUntil > now() or isempty(ValidUntil))
| join kind=innerunique (CloudAppEvents
| where TimeGenerated >= ago(dt_lookBack)
| extend Url = extract("(http[s]?://(?:[a-zA-Z]|[0-9]|[$-_@.&+]|[!*\\(\\),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+)", 1, tostring(ActivityObjects))
| extend userPrincipalName = tostring(RawEventData.UserId)
| extend TargetResourceDisplayName = tostring(ActivityObjects[0].displayName)
| extend CloudApps_TimeGenerated = TimeGenerated) on Url
| where CloudApps_TimeGenerated < ValidUntil
| summarize CloudApps_TimeGenerated = argmax(CloudApps_TimeGenerated, *) by IndicatorId, Url
| extend
Description = column_ifexists("max_CloudApps_TimeGenerated_Description", ""),
ActivityGroupNames = column_ifexists("max_CloudApps_TimeGenerated_ActivityGroupNames", ""),
ThreatType = column_ifexists("max_CloudApps_TimeGenerated_ThreatType", ""),
ExpirationDateTime = column_ifexists("max_CloudApps_TimeGenerated_ExpirationDateTime", ""),
ConfidenceScore = column_ifexists("max_CloudApps_TimeGenerated_ConfidenceScore", ""),
IPAddress = column_ifexists("max_CloudApps_TimeGenerated_IPAddress", ""),
AccountObjectId = column_ifexists("max_CloudApps_TimeGenerated_AccountObjectId", ""),
AccountDisplayName = column_ifexists("max_CloudApps_TimeGenerated_AccountDisplayName", ""),
ObjectName = column_ifexists("max_CloudApps_TimeGenerated_ObjectName", ""),
Application = column_ifexists("max_CloudApps_TimeGenerated_Application", ""),
ApplicationID = column_ifexists("max_CloudApps_TimeGenerated_ApplicationId", ""),
userPrincipalName = column_ifexists("max_CloudApps_TimeGenerated_userPrincipalName", "")
| project CloudApps_TimeGenerated, Description, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, Url, IPAddress, userPrincipalName, AccountObjectId, AccountDisplayName, ObjectName, Application, ApplicationID
entityMappings:
- entityType: Account
fieldMappings:
- identifier: ObjectGuid
columnName: AccountObjectId
- identifier: FullName
columnName: userPrincipalName
- identifier: DisplayName
columnName: AccountDisplayName
- entityType: URL
fieldMappings:
- identifier: Url
columnName: Url
- entityType: IP
fieldMappings:
- identifier: Address
columnName: IPAddress
- entityType: CloudApplication
fieldMappings:
- identifier: Name
columnName: Application
- identifier: AppId
columnName: ApplicationID
version: 1.0.6
kind: Scheduled
Stages and Predicates
Parameters
let dt_lookBack = 1h;
let ioc_lookBack = 14d;
Stage 1: source
ThreatIntelIndicators
Stage 2: extend
| extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
Stage 3: where
| where IndicatorType == "url"
Stage 4: extend
| extend Url = ObservableValue
Stage 5: extend
| extend IndicatorId = tostring(split(Id, "--")[2])
Stage 6: where
| where TimeGenerated >= ago(ioc_lookBack)
Stage 7: summarize
| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId, ObservableValue
Stage 8: where
| where IsActive and (ValidUntil > now() or isempty(ValidUntil))
Stage 9: join
| join kind=innerunique (CloudAppEvents
| where TimeGenerated >= ago(dt_lookBack)
| extend Url = extract("(http[s]?://(?:[a-zA-Z]|[0-9]|[$-_@.&+]|[!*\\(\\),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+)", 1, tostring(ActivityObjects))
| extend userPrincipalName = tostring(RawEventData.UserId)
| extend TargetResourceDisplayName = tostring(ActivityObjects[0].displayName)
| extend CloudApps_TimeGenerated = TimeGenerated) on Url
Stage 10: where
| where CloudApps_TimeGenerated < ValidUntil
Stage 11: summarize
| summarize CloudApps_TimeGenerated = argmax(CloudApps_TimeGenerated, *) by IndicatorId, Url
Stage 12: extend
| extend
Description = column_ifexists("max_CloudApps_TimeGenerated_Description", ""),
ActivityGroupNames = column_ifexists("max_CloudApps_TimeGenerated_ActivityGroupNames", ""),
ThreatType = column_ifexists("max_CloudApps_TimeGenerated_ThreatType", ""),
ExpirationDateTime = column_ifexists("max_CloudApps_TimeGenerated_ExpirationDateTime", ""),
ConfidenceScore = column_ifexists("max_CloudApps_TimeGenerated_ConfidenceScore", ""),
IPAddress = column_ifexists("max_CloudApps_TimeGenerated_IPAddress", ""),
AccountObjectId = column_ifexists("max_CloudApps_TimeGenerated_AccountObjectId", ""),
AccountDisplayName = column_ifexists("max_CloudApps_TimeGenerated_AccountDisplayName", ""),
ObjectName = column_ifexists("max_CloudApps_TimeGenerated_ObjectName", ""),
Application = column_ifexists("max_CloudApps_TimeGenerated_Application", ""),
ApplicationID = column_ifexists("max_CloudApps_TimeGenerated_ApplicationId", ""),
userPrincipalName = column_ifexists("max_CloudApps_TimeGenerated_userPrincipalName", "")
Stage 13: project
| project CloudApps_TimeGenerated, Description, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, Url, IPAddress, userPrincipalName, AccountObjectId, AccountDisplayName, ObjectName, Application, ApplicationID
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
CloudApps_TimeGenerated | lt |
|
IndicatorType | eq |
|
ValidUntil | is_null |
Output fields
Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.
| Field | Source |
|---|---|
AccountDisplayName | project |
AccountObjectId | project |
Application | project |
ApplicationID | project |
CloudApps_TimeGenerated | project |
ConfidenceScore | project |
Description | project |
ExpirationDateTime | project |
IPAddress | project |
IndicatorId | project |
ObjectName | project |
ThreatType | project |
Url | project |
userPrincipalName | project |