Detection rules › Kusto
VMware ESXi - Low patch disk space
'This rule is triggered when low patch disk store space is detected.'
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Impact | T1529 System Shutdown/Reboot |
Rule body kusto
id: 48d992ba-d404-4159-a8c6-46f51d1325c7
name: VMware ESXi - Low patch disk space
description: |
'This rule is triggered when low patch disk store space is detected.'
severity: Medium
status: Available
requiredDataConnectors:
- connectorId: SyslogAma
datatypes:
- Syslog
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
- Impact
relevantTechniques:
- T1529
query: |
let threshold = 100;
VMwareESXi
| where SyslogMessage has ('Patch store disk')
| extend sp = toreal(extract(@'free space is:\s(\d+)', 1, SyslogMessage)) / 1000000000
| where sp < threshold
| extend h = 'Hypervisor'
| extend HostCustomEntity = h
entityMappings:
- entityType: Host
fieldMappings:
- identifier: FullName
columnName: HostCustomEntity
version: 1.0.2
kind: Scheduled
Stages and Predicates
Parameters
let threshold = 100;
Stage 1: source
VMwareESXi
Stage 2: where
| where SyslogMessage has ('Patch store disk')
Stage 3: extend
| extend sp = toreal(extract(@'free space is:\s(\d+)', 1, SyslogMessage)) / 1000000000
Stage 4: where
| where sp < threshold
Stage 5: extend
| extend h = 'Hypervisor'
Stage 6: extend
| extend HostCustomEntity = h
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 |
|---|---|---|
SyslogMessage | match |
|
sp | lt |
|
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 |
|---|---|
sp | extend |
h | extend |
HostCustomEntity | extend |