Detection rules › Sigma

Usage of Renamed Sysinternals Tools - RegistrySet

Status
test
Severity
high
Log source
product windows, category registry_set
Author
Nasreddine Bencherchali (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects non-sysinternals tools setting the "accepteula" key which normally is set on sysinternals tool execution

MITRE ATT&CK coverage

TacticTechniques
Resource DevelopmentT1588.002 Obtain Capabilities: Tool

Event coverage

ProviderEventTitle
SysmonEvent ID 13RegistryEvent (Value Set)

Rule body yaml

title: Usage of Renamed Sysinternals Tools - RegistrySet
id: 8023f872-3f1d-4301-a384-801889917ab4
related:
    - id: 25ffa65d-76d8-4da5-a832-3f2b0136e133
      type: derived
    - id: f50f3c09-557d-492d-81db-9064a8d4e211
      type: similar
status: test
description: Detects non-sysinternals tools setting the "accepteula" key which normally is set on sysinternals tool execution
references:
    - Internal Research
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-08-24
modified: 2023-08-17
tags:
    - attack.resource-development
    - attack.t1588.002
logsource:
    product: windows
    category: registry_set
detection:
    selection:
        TargetObject|contains:
            - '\PsExec'
            - '\ProcDump'
            - '\Handle'
            - '\LiveKd'
            - '\Process Explorer'
            - '\PsLoglist'
            - '\PsPasswd'
            - '\Active Directory Explorer'
        TargetObject|endswith: '\EulaAccepted'
    filter_main_image_names:
        Image|endswith:
            - '\PsExec.exe'
            - '\PsExec64.exe'
            - '\procdump.exe'
            - '\procdump64.exe'
            - '\handle.exe'
            - '\handle64.exe'
            - '\livekd.exe'
            - '\livekd64.exe'
            - '\procexp.exe'
            - '\procexp64.exe'
            - '\psloglist.exe'
            - '\psloglist64.exe'
            - '\pspasswd.exe'
            - '\pspasswd64.exe'
            - '\ADExplorer.exe'
            - '\ADExplorer64.exe'
    filter_optional_null:
        Image: null # Race condition with some logging tools
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: condition

selection and not 1 of filter_main_* and not 1 of filter_optional_*

Stage 1: selection

selection:
    TargetObject|contains:
        - '\PsExec'
        - '\ProcDump'
        - '\Handle'
        - '\LiveKd'
        - '\Process Explorer'
        - '\PsLoglist'
        - '\PsPasswd'
        - '\Active Directory Explorer'
    TargetObject|endswith: '\EulaAccepted'

Stage 2: not filter_main_image_names

filter_main_image_names:
    Image|endswith:
        - '\PsExec.exe'
        - '\PsExec64.exe'
        - '\procdump.exe'
        - '\procdump64.exe'
        - '\handle.exe'
        - '\handle64.exe'
        - '\livekd.exe'
        - '\livekd64.exe'
        - '\procexp.exe'
        - '\procexp64.exe'
        - '\psloglist.exe'
        - '\psloglist64.exe'
        - '\pspasswd.exe'
        - '\pspasswd64.exe'
        - '\ADExplorer.exe'
        - '\ADExplorer64.exe'

Stage 3: not filter_optional_null

filter_optional_null:
    Image: null

Exclusions

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

FieldKindExcluded values
Imageends_with\ADExplorer.exe
Imageends_with\ADExplorer64.exe
Imageends_with\PsExec.exe
Imageends_with\PsExec64.exe
Imageends_with\handle.exe
Imageends_with\handle64.exe
Imageends_with\livekd.exe
Imageends_with\livekd64.exe
Imageends_with\procdump.exe
Imageends_with\procdump64.exe
Imageends_with\procexp.exe
Imageends_with\procexp64.exe
Imageends_with\psloglist.exe
Imageends_with\psloglist64.exe
Imageends_with\pspasswd.exe
Imageends_with\pspasswd64.exe
Imageis_null(no value, null check)

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
TargetObjectends_with
  • \EulaAccepted corpus 4 (sigma 4)
TargetObjectmatch
  • \Active Directory Explorer corpus 3 (sigma 3)
  • \Handle corpus 3 (sigma 3)
  • \LiveKd corpus 3 (sigma 3)
  • \ProcDump corpus 3 (sigma 3)
  • \Process Explorer corpus 3 (sigma 3)
  • \PsExec corpus 3 (sigma 3)
  • \PsLoglist corpus 3 (sigma 3)
  • \PsPasswd corpus 3 (sigma 3)