Detection rules › Kusto
Cisco SEG - Multiple suspiciuos attachments received
'Detects possibly phishing emails.'
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access |
Rule body
id: dfdb9a73-4335-4bb4-b29b-eb713bce61a6
name: Cisco SEG - Multiple suspiciuos attachments received
description: |
'Detects possibly phishing emails.'
severity: High
status: Available
requiredDataConnectors:
- connectorId: CefAma
dataTypes:
- CommonSecurityLog
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
- InitialAccess
relevantTechniques:
- T1566
query: |
let r_threshold = 5;
CiscoSEGEvent
| where NetworkDirection =~ 'Incoming'
| where isnotempty(EventMessage)
| where strlen(EventMessage) < 20
| summarize rec=makeset(DstUserName) by EventMessage, bin(TimeGenerated, 10m)
| where array_length(rec) > r_threshold
| extend AccountCustomEntity = rec
entityMappings:
- entityType: Account
fieldMappings:
- identifier: Name
columnName: AccountCustomEntity
version: 1.0.3
kind: Scheduled
Stages and Predicates
Parameters
let r_threshold = 5;
Stage 1: source
CiscoSEGEvent
Stage 2: where
| where NetworkDirection =~ 'Incoming'
Stage 3: where
| where isnotempty(EventMessage)
Stage 4: where
| where strlen(EventMessage) < 20
Stage 5: summarize
| summarize rec=makeset(DstUserName) by EventMessage, bin(TimeGenerated, 10m)
Stage 6: where
| where array_length(rec) > r_threshold
Stage 7: extend
| extend AccountCustomEntity = rec
Indicators
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
EventMessage | is_not_null | field:"EventMessage" kind:is_not_null | |
EventMessage | lt |
| field:"EventMessage" kind:lt value:"20" |
NetworkDirection | eq |
| field:"NetworkDirection" kind:eq value:"Incoming" |
Output fields
These fields are emitted when the rule matches.
| Field | Source |
|---|---|
EventMessage | summarize |
rec | summarize |
AccountCustomEntity | extend |