Detection rules › Kusto
Digital Guardian - Exfiltration to private email
'Detects exfiltration to private email.'
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Exfiltration |
Rule body
id: edead9b5-243a-466b-ae78-2dae32ab1117
name: Digital Guardian - Exfiltration to private email
description: |
'Detects exfiltration to private email.'
severity: High
status: Available
requiredDataConnectors:
- connectorId: SyslogAma
datatypes:
- Syslog
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
- Exfiltration
relevantTechniques:
- T1048
query: |
DigitalGuardianDLPEvent
| where NetworkApplicationProtocol =~ 'SMTP'
| where isnotempty(inspected_document)
| extend s_user = substring(SrcUserName, 0, indexof(SrcUserName, '@'))
| extend d_user = substring(DstUserName, 0, indexof(DstUserName, '@'))
| extend s_domain = extract(@'@(.*)', 1, SrcUserName)
| extend d_domain = extract(@'@(.*)', 1, DstUserName)
| where s_domain != d_domain
| where s_user == d_user
| extend AccountCustomEntity = SrcUserName
entityMappings:
- entityType: Account
fieldMappings:
- identifier: Name
columnName: AccountCustomEntity
version: 1.0.2
kind: Scheduled
Stages and Predicates
Stage 1: source
DigitalGuardianDLPEvent
Stage 2: where
| where NetworkApplicationProtocol =~ 'SMTP'
Stage 3: where
| where isnotempty(inspected_document)
Stage 4: extend (4 consecutive steps)
| extend s_user = substring(SrcUserName, 0, indexof(SrcUserName, '@'))
| extend d_user = substring(DstUserName, 0, indexof(DstUserName, '@'))
| extend s_domain = extract(@'@(.*)', 1, SrcUserName)
| extend d_domain = extract(@'@(.*)', 1, DstUserName)
Stage 5: where
| where s_domain != d_domain
Stage 6: where
| where s_user == d_user
Stage 7: extend
| extend AccountCustomEntity = SrcUserName
Indicators
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
NetworkApplicationProtocol | eq |
| field:"NetworkApplicationProtocol" kind:eq value:"SMTP" |
inspected_document | is_not_null | field:"inspected_document" kind:is_not_null | |
s_domain | cross_field_compare |
| field:"s_domain" kind:cross_field_compare value:"d_domain" |
s_user | cross_field_compare |
| field:"s_user" kind:cross_field_compare value:"d_user" |
Output fields
These fields are emitted when the rule matches.
| Field | Source |
|---|---|
s_user | extend |
d_user | extend |
s_domain | extend |
d_domain | extend |
AccountCustomEntity | extend |