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Detection rules › Sigma

Renamed PsExec Service Execution

Status
test
Severity
high
Log source
product windows, category process_creation
Author
Florian Roth (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects suspicious launch of a renamed version of the PSEXESVC service with, which is not often used by legitimate administrators

MITRE ATT&CK coverage

TacticTechniques
ExecutionNo specific technique

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: Renamed PsExec Service Execution
id: 51ae86a2-e2e1-4097-ad85-c46cb6851de4
status: test
description: Detects suspicious launch of a renamed version of the PSEXESVC service with, which is not often used by legitimate administrators
references:
    - https://learn.microsoft.com/en-us/sysinternals/downloads/psexec
    - https://www.youtube.com/watch?v=ro2QuZTIMBM
author: Florian Roth (Nextron Systems)
date: 2022-07-21
tags:
    - attack.execution
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        OriginalFileName: 'psexesvc.exe'
    filter:
        Image: 'C:\Windows\PSEXESVC.exe'
    condition: selection and not filter
falsepositives:
    - Legitimate administrative tasks
level: high

Stages and Predicates

Stage 0: condition

selection and not filter

Stage 1: selection

selection:
    OriginalFileName: 'psexesvc.exe'

Stage 2: not filter

filter:
    Image: 'C:\Windows\PSEXESVC.exe'

Exclusions

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

FieldKindExcluded values
ImageeqC:\Windows\PSEXESVC.exe

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
OriginalFileNameeq
  • psexesvc.exe corpus 4 (sigma 3, elastic 1)