Detection rules › Kusto
Excessive Amount of Denied Connections from a Single Source
'This creates an incident in the event that a single source IP address generates a excessive amount of denied connections.'
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Impact | T1499 Endpoint Denial of Service |
Rule body kusto
id: 3d645a88-2724-41a7-adea-db74c439cf79
name: Excessive Amount of Denied Connections from a Single Source
description: |
'This creates an incident in the event that a single source IP address generates a excessive amount of denied connections.'
severity: Medium
status: Available
requiredDataConnectors:
- connectorId: SyslogAma
datatypes:
- Syslog
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
- Impact
relevantTechniques:
- T1499
query: |
let threshold = 5000;
SophosXGFirewall
| where Log_Type =~ "Firewall" and Status =~ "Deny"
| summarize count() by Src_IP, bin(TimeGenerated,5m)
| where count_ > threshold
entityMappings:
- entityType: IP
fieldMappings:
- identifier: Address
columnName: Src_IP
version: 1.0.4
kind: Scheduled
Stages and Predicates
Parameters
let threshold = 5000;
Stage 1: source
SophosXGFirewall
Stage 2: where
| where Log_Type =~ "Firewall" and Status =~ "Deny"
Stage 3: summarize
| summarize count() by Src_IP, bin(TimeGenerated,5m)
Stage 4: where
| where count_ > threshold
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.
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 |
|---|---|
Src_IP | summarize |