Detection rules › Kusto

Potential re-named sdelete usage

Status
available
Severity
low
Time window
1h
Source
github.com/Azure/Azure-Sentinel

This detection looks for command line parameters associated with the use of Sysinternals sdelete (https://docs.microsoft.com/sysinternals/downloads/sdelete) to delete multiple files on a host's C drive. A threat actor may re-name the tool to avoid detection and then use it for destructive attacks on a host.

MITRE ATT&CK coverage

TacticTechniques
StealthT1036 Masquerading
ImpactT1485 Data Destruction

Event coverage

Rule body kusto

id: 720d12c6-a08c-44c4-b18f-2236412d59b0
name: Potential re-named sdelete usage
description: |
  'This detection looks for command line parameters associated with the use of Sysinternals sdelete (https://docs.microsoft.com/sysinternals/downloads/sdelete) to delete multiple files on a host's C drive.
  A threat actor may re-name the tool to avoid detection and then use it for destructive attacks on a host.'
severity: Low
requiredDataConnectors:
  - connectorId: SecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: WindowsSecurityEvents
    dataTypes:
      - SecurityEvent
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
status: Available
tactics:
  - DefenseEvasion
  - Impact
relevantTechniques:
  - T1485
  - T1036
query: |
  SecurityEvent
    | where EventID == 4688
    | where Process !~ "sdelete.exe"
    | where CommandLine has_all ("accepteula", "-r", "-s", "-q", "c:/")
    | where CommandLine !has ("sdelete")
    | extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
    | extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
    | extend AccountName = tostring(split(TargetAccount, @'\')[1]), AccountNTDomain = tostring(split(TargetAccount, @'\')[0])
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: TargetAccount
      - identifier: Name
        columnName: AccountName
      - identifier: NTDomain
        columnName: AccountNTDomain
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: Computer
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: HostNameDomain
version: 1.0.3
kind: Scheduled

Stages and Predicates

Stage 1: source

SecurityEvent

Stage 2: where

| where EventID == 4688

Stage 3: where

| where Process !~ "sdelete.exe"

Stage 4: where

| where CommandLine has_all ("accepteula", "-r", "-s", "-q", "c:/")

Stage 5: where

| where CommandLine !has ("sdelete")

Stage 6: extend (3 consecutive steps)

| extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
| extend AccountName = tostring(split(TargetAccount, @'\')[1]), AccountNTDomain = tostring(split(TargetAccount, @'\')[0])

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
CommandLinematchsdelete

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.

FieldKindValues
CommandLinematch
  • -q corpus 9 (sigma 6, kusto 2, splunk 1)
  • -r corpus 13 (sigma 9, kusto 4)
  • -s corpus 10 (sigma 4, kusto 4, elastic 1, splunk 1)
  • accepteula corpus 7 (sigma 3, kusto 3, splunk 1)
  • c:/
EventIDeq
  • 4688 transforms: cased corpus 313 (splunk 283, kusto 30)
Processne
  • sdelete.exe

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.

FieldSource
DomainIndexextend
HostNameextend
HostNameDomainextend
AccountNTDomainextend
AccountNameextend