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Detection rules › Sigma

Sdiagnhost Calling Suspicious Child Process

Status
test
Severity
high
Log source
product windows, category process_creation
Author
Nextron Systems, @Kostastsale
Source
github.com/SigmaHQ/sigma

Detects sdiagnhost.exe calling a suspicious child process (e.g. used in exploits for Follina / CVE-2022-30190)

MITRE ATT&CK coverage

TacticTechniques
StealthT1036 Masquerading, T1218 System Binary Proxy Execution

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation
Security-AuditingEvent ID 4688A new process has been created.

Rule body yaml

title: Sdiagnhost Calling Suspicious Child Process
id: f3d39c45-de1a-4486-a687-ab126124f744
status: test
description: Detects sdiagnhost.exe calling a suspicious child process (e.g. used in exploits for Follina / CVE-2022-30190)
references:
    - https://twitter.com/nao_sec/status/1530196847679401984
    - https://doublepulsar.com/follina-a-microsoft-office-code-execution-vulnerability-1a47fce5629e
    - https://app.any.run/tasks/713f05d2-fe78-4b9d-a744-f7c133e3fafb/
    - https://app.any.run/tasks/f420d295-0457-4e9b-9b9e-6732be227583/
    - https://app.any.run/tasks/c4117d9a-f463-461a-b90f-4cd258746798/
author: Nextron Systems, @Kostastsale
date: 2022-06-01
modified: 2024-08-23
tags:
    - attack.stealth
    - attack.t1036
    - attack.t1218
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\sdiagnhost.exe'
        Image|endswith:
            # Add more suspicious LOLBins
            - '\powershell.exe'
            - '\pwsh.exe'
            - '\cmd.exe'
            - '\mshta.exe'
            - '\cscript.exe'
            - '\wscript.exe'
            - '\taskkill.exe'
            - '\regsvr32.exe'
            - '\rundll32.exe'
            # - '\csc.exe'   # https://app.any.run/tasks/f420d295-0457-4e9b-9b9e-6732be227583/
            - '\calc.exe'  # https://app.any.run/tasks/f420d295-0457-4e9b-9b9e-6732be227583/
    filter_main_cmd_bits:
        Image|endswith: '\cmd.exe'
        CommandLine|contains: 'bits'
    filter_main_powershell_noprofile:
        Image|endswith: '\powershell.exe'
        CommandLine|endswith:
            - '-noprofile -'
            - '-noprofile'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

selection and not 1 of filter_main_*

Stage 1: selection

selection:
    ParentImage|endswith: '\sdiagnhost.exe'
    Image|endswith:
        - '\powershell.exe'
        - '\pwsh.exe'
        - '\cmd.exe'
        - '\mshta.exe'
        - '\cscript.exe'
        - '\wscript.exe'
        - '\taskkill.exe'
        - '\regsvr32.exe'
        - '\rundll32.exe'
        - '\calc.exe'

Stage 2: not filter_main_*

filter_main_cmd_bits:
    Image|endswith: '\cmd.exe'
    CommandLine|contains: 'bits'
filter_main_powershell_noprofile:
    Image|endswith: '\powershell.exe'
    CommandLine|endswith:
        - '-noprofile -'
        - '-noprofile'

Exclusions

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

FieldKindExcluded values
CommandLineends_with-noprofile -
CommandLineends_with-noprofile
Imageends_with\powershell.exe
CommandLinematchbits
Imageends_with\cmd.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
Imageends_with
  • \calc.exe corpus 13 (sigma 13)
  • \cmd.exe corpus 130 (sigma 130)
  • \cscript.exe corpus 73 (sigma 73)
  • \mshta.exe corpus 67 (sigma 67)
  • \powershell.exe corpus 182 (sigma 182)
  • \pwsh.exe corpus 168 (sigma 168)
  • \regsvr32.exe corpus 65 (sigma 65)
  • \rundll32.exe corpus 95 (sigma 95)
  • \taskkill.exe corpus 4 (sigma 4)
  • \wscript.exe corpus 75 (sigma 75)
ParentImageends_with
  • \sdiagnhost.exe