Detection rules › Kusto
TI map Email entity to SigninLogs
'Identifies a match in SigninLogs table from any Email IOC from TI'
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access | T1566 Phishing |
Rule body kusto
id: 4b5a7f32-899d-4d22-8de2-0ec90b911a72
name: TI map Email entity to SigninLogs
description: |
'Identifies a match in SigninLogs table from any Email IOC from TI'
severity: Medium
requiredDataConnectors:
- connectorId: ThreatIntelligence
dataTypes:
- ThreatIntelIndicators
- connectorId: ThreatIntelligenceTaxii
dataTypes:
- ThreatIntelIndicators
- connectorId: AzureActiveDirectory
dataTypes:
- SigninLogs
- connectorId: AzureActiveDirectory
dataTypes:
- AADNonInteractiveUserSignInLogs
- connectorId: MicrosoftDefenderThreatIntelligence
dataTypes:
- ThreatIntelIndicators
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
- InitialAccess
relevantTechniques:
- T1566
query: |
let dt_lookBack = 1h;
let ioc_lookBack = 14d;
let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';
let Signins = materialize(union isfuzzy=true
( SigninLogs | where TimeGenerated >= ago(dt_lookBack)),
( AADNonInteractiveUserSignInLogs | where TimeGenerated >= ago(dt_lookBack)
| extend Status = todynamic(Status), LocationDetails = todynamic(LocationDetails))
| where isnotempty(UserPrincipalName) and UserPrincipalName matches regex emailregex
| extend UserPrincipalName = tolower(UserPrincipalName)
| extend Status = todynamic(Status), LocationDetails = todynamic(LocationDetails)
| extend StatusCode = tostring(Status.errorCode), StatusDetails = tostring(Status.additionalDetails)
| extend State = tostring(LocationDetails.state), City = tostring(LocationDetails.city), Region = tostring(LocationDetails.countryOrRegion)
| extend SigninLogs_TimeGenerated = TimeGenerated);
let SigninUPNs = Signins | distinct UserPrincipalName | summarize make_list(UserPrincipalName);
ThreatIntelIndicators
//Filtering the table for Email related IOCs
| extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
| where IndicatorType == "email-addr"
| extend EmailSenderAddress = ObservableValue
| extend EmailSourceDomain = substring(EmailSenderAddress, indexof(EmailSenderAddress, "@") + 1, strlen(EmailSenderAddress) - indexof(EmailSenderAddress, "@") - 1)
| extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
| extend Id = tostring(split(Id, "--")[2])
| extend Url = iff(ObservableKey == "url:value", ObservableValue, "")
| where TimeGenerated >= ago(ioc_lookBack)
| where EmailSenderAddress in (SigninUPNs)
| 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;"
| project-reorder *, TrafficLightProtocolLevel, EmailSenderAddress, EmailSourceDomain, Type
| join kind=innerunique (Signins) on $left.EmailSenderAddress == $right.UserPrincipalName
| where SigninLogs_TimeGenerated < ValidUntil
| summarize SigninLogs_TimeGenerated = arg_max(SigninLogs_TimeGenerated, *) by Id, UserPrincipalName
| extend Description = tostring(parse_json(Data).description)
| extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
| project SigninLogs_TimeGenerated, Description, ActivityGroupNames, Id, ValidUntil, Confidence, EmailSenderAddress, IPAddress, UserPrincipalName, AppDisplayName, StatusCode, StatusDetails, NetworkLocationDetails, Type, Url
| extend Name = tostring(split(UserPrincipalName, '@', 0)[0]), UPNSuffix = tostring(split(UserPrincipalName, '@', 1)[0])
| extend timestamp = SigninLogs_TimeGenerated
entityMappings:
- entityType: Account
fieldMappings:
- identifier: FullName
columnName: UserPrincipalName
- identifier: Name
columnName: Name
- identifier: UPNSuffix
columnName: UPNSuffix
- entityType: IP
fieldMappings:
- identifier: Address
columnName: IPAddress
- entityType: URL
fieldMappings:
- identifier: Url
columnName: Url
version: 1.2.11
kind: Scheduled
Stages and Predicates
Parameters
let dt_lookBack = 1h;
let ioc_lookBack = 14d;
let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';
Let binding: Signins
let Signins = materialize(union isfuzzy=true
( SigninLogs | where TimeGenerated >= ago(dt_lookBack)),
( AADNonInteractiveUserSignInLogs | where TimeGenerated >= ago(dt_lookBack)
| extend Status = todynamic(Status), LocationDetails = todynamic(LocationDetails))
| where isnotempty(UserPrincipalName) and UserPrincipalName matches regex emailregex
| extend UserPrincipalName = tolower(UserPrincipalName)
| extend Status = todynamic(Status), LocationDetails = todynamic(LocationDetails)
| extend StatusCode = tostring(Status.errorCode), StatusDetails = tostring(Status.additionalDetails)
| extend State = tostring(LocationDetails.state), City = tostring(LocationDetails.city), Region = tostring(LocationDetails.countryOrRegion)
| extend SigninLogs_TimeGenerated = TimeGenerated);
Derived from dt_lookBack, emailregex.
Let binding: SigninUPNs
let SigninUPNs = Signins | distinct UserPrincipalName | summarize make_list(UserPrincipalName);
Derived from Signins.
Stage 1: source
ThreatIntelIndicators
Stage 2: extend
| extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
Stage 3: where
| where IndicatorType == "email-addr"
Stage 4: extend (5 consecutive steps)
| extend EmailSenderAddress = ObservableValue
| extend EmailSourceDomain = substring(EmailSenderAddress, indexof(EmailSenderAddress, "@") + 1, strlen(EmailSenderAddress) - indexof(EmailSenderAddress, "@") - 1)
| extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
| extend Id = tostring(split(Id, "--")[2])
| extend Url = iff(ObservableKey == "url:value", ObservableValue, "")
Stage 5: where
| where TimeGenerated >= ago(ioc_lookBack)
Stage 6: where
| where EmailSenderAddress in (SigninUPNs)
References SigninUPNs (defined above).
Stage 7: summarize
| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue
Stage 8: where
| where IsActive and (ValidUntil > now() or isempty(ValidUntil))
Stage 9: extend
| extend Description = tostring(parse_json(Data).description)
Stage 10: where
| where Description !contains_cs "State: inactive;" and Description !contains_cs "State: falsepos;"
Stage 11: project-reorder
| project-reorder *, TrafficLightProtocolLevel, EmailSenderAddress, EmailSourceDomain, Type
Stage 12: join
| join kind=innerunique (Signins) on $left.EmailSenderAddress == $right.UserPrincipalName
Stage 13: where
| where SigninLogs_TimeGenerated < ValidUntil
Stage 14: summarize
| summarize SigninLogs_TimeGenerated = arg_max(SigninLogs_TimeGenerated, *) by Id, UserPrincipalName
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 SigninLogs_TimeGenerated, Description, ActivityGroupNames, Id, ValidUntil, Confidence, EmailSenderAddress, IPAddress, UserPrincipalName, AppDisplayName, StatusCode, StatusDetails, NetworkLocationDetails, Type, Url
Stage 18: extend
| extend Name = tostring(split(UserPrincipalName, '@', 0)[0]), UPNSuffix = tostring(split(UserPrincipalName, '@', 1)[0])
Stage 19: extend
| extend timestamp = SigninLogs_TimeGenerated
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 |
|---|---|---|
EmailSenderAddress | in |
|
IndicatorType | eq |
|
SigninLogs_TimeGenerated | lt |
|
UserPrincipalName | is_not_null | |
UserPrincipalName | regex_match |
|
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 |
AppDisplayName | project |
Confidence | project |
Description | project |
EmailSenderAddress | project |
IPAddress | project |
Id | project |
NetworkLocationDetails | project |
SigninLogs_TimeGenerated | project |
StatusCode | project |
StatusDetails | project |
Type | project |
Url | project |
UserPrincipalName | project |
ValidUntil | project |
Name | extend |
UPNSuffix | extend |
timestamp | extend |