Detection rules › Kusto
TI Map URL Entity to AuditLogs
'This query identifies any URL indicators of compromise (IOCs) from threat intelligence (TI) by searching for matches in AuditLogs.'
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Command & Control | T1071 Application Layer Protocol |
Rule body kusto
id: 9991c277-e0a1-4079-8c40-fbfca2705615
name: TI Map URL Entity to AuditLogs
description: |
'This query identifies any URL indicators of compromise (IOCs) from threat intelligence (TI) by searching for matches in AuditLogs.'
severity: Medium
requiredDataConnectors:
- connectorId: AzureActiveDirectory
dataTypes:
- AuditLogs
- connectorId: ThreatIntelligence
dataTypes:
- ThreatIntelIndicators
- connectorId: ThreatIntelligenceTaxii
dataTypes:
- ThreatIntelIndicators
- 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;
let AuditEvents = materialize(AuditLogs
| where TimeGenerated >= ago(dt_lookBack)
// Extract the URL that is contained within the JSON data
| extend Url = extract("(http[s]?://(?:[a-zA-Z]|[0-9]|[$-_@.&+]|[!*\\(\\),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+)", 1,tostring(TargetResources))
| extend userPrincipalName = tostring(parse_json(tostring(InitiatedBy.user)).userPrincipalName)
| extend TargetResourceDisplayName = tostring(TargetResources[0].displayName));
let AuditUrls = AuditEvents | distinct Url = tolower(Url) | summarize make_list(Url);
ThreatIntelIndicators
//extract key part of kv pair
| extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
| where IndicatorType == "url"
| extend Url = toupper(ObservableValue)
| extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
| where TimeGenerated >= ago(ioc_lookBack)
| where tolower(Url) in (AuditUrls)
| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue
| where IsActive and (ValidUntil > now() or isempty(ValidUntil))
| extend Description = tostring(parse_json(Data).description)
| where Description !contains_cs "State: inactive;" and Description !contains_cs "State: falsepos;"
// using innerunique to keep perf fast and result set low, we only need one match to indicate potential malicious activity that needs to be investigated
| join kind=innerunique (AuditEvents) on Url
| where TimeGenerated < ValidUntil
| summarize TimeGenerated = arg_max(TimeGenerated, *) by Id, Url
| extend Description = tostring(parse_json(Data).description)
| extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
| project TimeGenerated, Description, ActivityGroupNames, Id, Type, ValidUntil, Confidence,
OperationName, Identity, userPrincipalName, TargetResourceDisplayName, Url
| extend AccountName = tostring(split(userPrincipalName, "@")[0]), AccountUPNSuffix = tostring(split(userPrincipalName, "@")[1])
| extend HostName = tostring(split(TargetResourceDisplayName, ".")[0]), DomainIndex = toint(indexof(TargetResourceDisplayName, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(TargetResourceDisplayName, DomainIndex + 1), TargetResourceDisplayName)
entityMappings:
- entityType: Account
fieldMappings:
- identifier: FullName
columnName: userPrincipalName
- identifier: Name
columnName: AccountName
- identifier: UPNSuffix
columnName: AccountUPNSuffix
- entityType: Host
fieldMappings:
- identifier: FullName
columnName: TargetResourceDisplayName
- identifier: HostName
columnName: HostName
- identifier: DnsDomain
columnName: HostNameDomain
- entityType: URL
fieldMappings:
- identifier: Url
columnName: Url
version: 1.2.10
kind: Scheduled
Stages and Predicates
Parameters
let dt_lookBack = 1h;
let ioc_lookBack = 14d;
Let binding: AuditEvents
let AuditEvents = materialize(AuditLogs
| 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(TargetResources))
| extend userPrincipalName = tostring(parse_json(tostring(InitiatedBy.user)).userPrincipalName)
| extend TargetResourceDisplayName = tostring(TargetResources[0].displayName));
Derived from dt_lookBack.
Let binding: AuditUrls
let AuditUrls = AuditEvents | distinct Url = tolower(Url) | summarize make_list(Url);
Derived from AuditEvents.
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 = toupper(ObservableValue)
Stage 5: extend
| extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
Stage 6: where
| where TimeGenerated >= ago(ioc_lookBack)
Stage 7: where
| where tolower(Url) in (AuditUrls)
References AuditUrls (defined above).
Stage 8: summarize
| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue
Stage 9: where
| where IsActive and (ValidUntil > now() or isempty(ValidUntil))
Stage 10: extend
| extend Description = tostring(parse_json(Data).description)
Stage 11: where
| where Description !contains_cs "State: inactive;" and Description !contains_cs "State: falsepos;"
Stage 12: join
| join kind=innerunique (AuditEvents) on Url
Stage 13: where
| where TimeGenerated < ValidUntil
Stage 14: summarize
| summarize TimeGenerated = arg_max(TimeGenerated, *) by Id, Url
Stage 15: extend
| extend Description = tostring(parse_json(Data).description)
Stage 16: extend
| extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
Stage 17: project
| project TimeGenerated, Description, ActivityGroupNames, Id, Type, ValidUntil, Confidence,
OperationName, Identity, userPrincipalName, TargetResourceDisplayName, Url
Stage 18: extend (3 consecutive steps)
| extend AccountName = tostring(split(userPrincipalName, "@")[0]), AccountUPNSuffix = tostring(split(userPrincipalName, "@")[1])
| extend HostName = tostring(split(TargetResourceDisplayName, ".")[0]), DomainIndex = toint(indexof(TargetResourceDisplayName, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(TargetResourceDisplayName, DomainIndex + 1), TargetResourceDisplayName)
Exclusions
Top-level NOT(...) conjuncts: predicates this rule actively suppresses.
| Field | Kind | Excluded values |
|---|---|---|
Description | contains | State: falsepos; |
Description | contains | State: inactive; |
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 |
|---|---|---|
IndicatorType | eq |
|
TimeGenerated | lt |
|
Url | in |
|
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 |
|---|---|
ActivityGroupNames | project |
Confidence | project |
Description | project |
Id | project |
Identity | project |
OperationName | project |
TargetResourceDisplayName | project |
TimeGenerated | project |
Type | project |
Url | project |
ValidUntil | project |
userPrincipalName | project |
AccountName | extend |
AccountUPNSuffix | extend |
DomainIndex | extend |
HostName | extend |
HostNameDomain | extend |