Detection rules › Kusto
Cisco SEG - Malicious attachment not blocked
'Detects mails with malicious attachments which were not blocked.'
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access | T1566 Phishing |
Rule body kusto
id: 236e872c-31d1-4b45-ac2a-fda3af465c97
name: Cisco SEG - Malicious attachment not blocked
description: |
'Detects mails with malicious attachments which were not blocked.'
severity: High
status: Available
requiredDataConnectors:
- connectorId: CefAma
dataTypes:
- CommonSecurityLog
queryFrequency: 10m
queryPeriod: 10m
triggerOperator: gt
triggerThreshold: 0
tactics:
- InitialAccess
relevantTechniques:
- T1566
query: |
CiscoSEGEvent
| where NetworkDirection =~ 'Incoming'
| where SimplifiedDeviceAction =~ 'DELIVERED'
| where tostring(AdditionalFields) has 'ESAAMPVerdict'
| extend amp_verdict = extract(@'ESAAMPVerdict":"(NOT_EVALUATED|CLEAN|FA_PENDING|UNKNOWN|SKIPPED|UNSCANNABLE|LOW_RISK|MALICIOUS)"', 1, tostring(AdditionalFields))
| where amp_verdict =~ 'MALICIOUS'
| extend AccountCustomEntity = DstUserName
entityMappings:
- entityType: Account
fieldMappings:
- identifier: Name
columnName: AccountCustomEntity
version: 1.0.3
kind: Scheduled
Stages and Predicates
Stage 1: source
CiscoSEGEvent
Stage 2: where
| where NetworkDirection =~ 'Incoming'
Stage 3: where
| where SimplifiedDeviceAction =~ 'DELIVERED'
Stage 4: where
| where tostring(AdditionalFields) has 'ESAAMPVerdict'
Stage 5: extend
| extend amp_verdict = extract(@'ESAAMPVerdict":"(NOT_EVALUATED|CLEAN|FA_PENDING|UNKNOWN|SKIPPED|UNSCANNABLE|LOW_RISK|MALICIOUS)"', 1, tostring(AdditionalFields))
Stage 6: where
| where amp_verdict =~ 'MALICIOUS'
Stage 7: extend
| extend AccountCustomEntity = DstUserName
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 |
|---|---|---|
AdditionalFields | match |
|
NetworkDirection | eq |
|
SimplifiedDeviceAction | eq |
|
amp_verdict | eq |
|
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 |
|---|---|
amp_verdict | extend |
AccountCustomEntity | extend |