MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access |
Rule body
id: c66b8ced-8c76-415b-a0f3-08c7030a857d
name: Cisco SEG - Unscannable attacment
description: |
'Detects unscannable attachments in mails.'
severity: Medium
status: Available
requiredDataConnectors:
- connectorId: CefAma
dataTypes:
- CommonSecurityLog
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
- InitialAccess
relevantTechniques:
- T1566
query: |
CiscoSEGEvent
| where NetworkDirection =~ 'Incoming'
| 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 =~ 'UNSCANNABLE'
| 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 tostring(AdditionalFields) has 'ESAAMPVerdict'
Stage 4: extend
| extend amp_verdict = extract(@'ESAAMPVerdict":"(NOT_EVALUATED|CLEAN|FA_PENDING|UNKNOWN|SKIPPED|UNSCANNABLE|LOW_RISK|MALICIOUS)"', 1, tostring(AdditionalFields))
Stage 5: where
| where amp_verdict =~ 'UNSCANNABLE'
Stage 6: extend
| extend AccountCustomEntity = DstUserName
Indicators
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
AdditionalFields | match |
| field:"AdditionalFields" kind:match value:"ESAAMPVerdict" |
NetworkDirection | eq |
| field:"NetworkDirection" kind:eq value:"Incoming" |
amp_verdict | eq |
| field:"amp_verdict" kind:eq value:"UNSCANNABLE" |
Output fields
These fields are emitted when the rule matches.
| Field | Source |
|---|---|
amp_verdict | extend |
AccountCustomEntity | extend |