Detection rules › Kusto
Cisco WSA - Multiple errors to resource from risky category
'Detects multiple connection errors to resource from risky category.'
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access | |
| Command & Control |
Rule body
id: ebf9db0c-ba7b-4249-b9ec-50a05fa7c7c9
name: Cisco WSA - Multiple errors to resource from risky category
description: |
'Detects multiple connection errors to resource from risky category.'
severity: Medium
status: Available
requiredDataConnectors:
- connectorId: SyslogAma
datatypes:
- Syslog
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
- InitialAccess
- CommandAndControl
relevantTechniques:
- T1189
- T1102
query: |
let threshold = 10;
let risky_sites = dynamic(['IW_adlt', 'IW_hack', 'IW_porn']);
CiscoWSAEvent
| where DvcAction startswith 'BLOCK_'
| where UrlCategory in~ (risky_sites)
| summarize count() by SrcUserName, UrlOriginal, bin(TimeGenerated, 5m)
| where count_ >= threshold
| extend URLCustomEntity = UrlOriginal, AccountCustomEntity = SrcUserName
entityMappings:
- entityType: URL
fieldMappings:
- identifier: Url
columnName: URLCustomEntity
- entityType: Account
fieldMappings:
- identifier: Name
columnName: AccountCustomEntity
version: 1.0.2
kind: Scheduled
Stages and Predicates
Parameters
let threshold = 10;
let risky_sites = dynamic(['IW_adlt', 'IW_hack', 'IW_porn']);
Stage 1: source
CiscoWSAEvent
Stage 2: where
| where DvcAction startswith 'BLOCK_'
Stage 3: where
| where UrlCategory in~ (risky_sites)
Stage 4: summarize
| summarize count() by SrcUserName, UrlOriginal, bin(TimeGenerated, 5m)
Stage 5: where
| where count_ >= threshold
Stage 6: extend
| extend URLCustomEntity = UrlOriginal, AccountCustomEntity = SrcUserName
Indicators
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
DvcAction | starts_with |
| field:"DvcAction" kind:starts_with value:"BLOCK_" |
UrlCategory | in |
| field:"UrlCategory" kind:in |
count_ | ge |
| field:"count_" kind:ge value:"10" |
Output fields
These fields are emitted when the rule matches.
| Field | Source |
|---|---|
SrcUserName | summarize |
UrlOriginal | summarize |
AccountCustomEntity | extend |
URLCustomEntity | extend |