Detection rules › Kusto
ClientDeniedAccess
'Creates an incident in the event a Client has an excessive amounts of denied access requests.'
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Credential Access | T1110 Brute Force |
Rule body kusto
id: a9956d3a-07a9-44a6-a279-081a85020cae
name: ClientDeniedAccess
description: |
'Creates an incident in the event a Client has an excessive amounts of denied access requests.'
severity: Medium
requiredDataConnectors:
- connectorId: SyslogAma
datatypes:
- Syslog
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
- CredentialAccess
relevantTechniques:
- T1110
query: |
let threshold = 15;
let rejectedAccess = SymantecVIP
| where isnotempty(RADIUSAuth)
| where RADIUSAuth =~ "Reject"
| summarize Total = count() by ClientIP, bin(TimeGenerated, 15m)
| where Total > threshold
| project ClientIP;
SymantecVIP
| where isnotempty(RADIUSAuth)
| where RADIUSAuth =~ "Reject"
| join kind=inner rejectedAccess on ClientIP
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated), count() by ClientIP, User
entityMappings:
- entityType: Account
fieldMappings:
- identifier: FullName
columnName: User
- entityType: IP
fieldMappings:
- identifier: Address
columnName: ClientIP
version: 1.0.4
status: Available
kind: Scheduled
Stages and Predicates
Parameters
let threshold = 15;
Let binding: rejectedAccess
let rejectedAccess = SymantecVIP
| where isnotempty(RADIUSAuth)
| where RADIUSAuth =~ "Reject"
| summarize Total = count() by ClientIP, bin(TimeGenerated, 15m)
| where Total > threshold
| project ClientIP;
Derived from threshold.
Stage 1: source
SymantecVIP
Stage 2: where
| where isnotempty(RADIUSAuth)
Stage 3: where
| where RADIUSAuth =~ "Reject"
Stage 4: join
| join kind=inner rejectedAccess on ClientIP
Stage 5: summarize
| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated), count() by ClientIP, User
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 |
|---|---|---|
RADIUSAuth | eq |
|
RADIUSAuth | is_not_null | |
Total | gt |
|
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 |
|---|---|
ClientIP | summarize |
EndTime | summarize |
StartTime | summarize |
User | summarize |