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Detection rules › Sigma

Potential Ryuk Ransomware Activity

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

Detects Ryuk ransomware activity

MITRE ATT&CK coverage

TacticTechniques
PersistenceT1547.001 Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder
Privilege EscalationT1547.001 Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder

Event coverage

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

Rule body yaml

title: Potential Ryuk Ransomware Activity
id: c37510b8-2107-4b78-aa32-72f251e7a844
related:
    - id: 58bf96d9-ff5f-44bd-8dcc-1c4f79bf3a27
      type: similar
    - id: 0acaad27-9f02-4136-a243-c357202edd74
      type: obsolete
status: stable
description: Detects Ryuk ransomware activity
references:
    - https://app.any.run/tasks/d860402c-3ff4-4c1f-b367-0237da714ed1/
    - https://research.checkpoint.com/ryuk-ransomware-targeted-campaign-break/
author: Florian Roth (Nextron Systems), Vasiliy Burov, Nasreddine Bencherchali (Nextron Systems)
date: 2019-12-16
modified: 2023-02-03
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.t1547.001
    - detection.emerging-threats
logsource:
    category: process_creation
    product: windows
detection:
    selection_reg:
        CommandLine|contains|all:
            - 'Microsoft\Windows\CurrentVersion\Run'
            - 'C:\users\Public\'
    selection_del:
        CommandLine|contains|all:
            - 'del /s /f /q c:\'
            - '\*.bac'
            - '\*.bak'
            - '\*.bkf'
    selection_net:
        Image|endswith:
            - '\net.exe'
            - '\net1.exe'
        CommandLine|contains|all:
            - ' stop '
            - ' /y'
        CommandLine|contains:
            - 'samss'
            - 'audioendpointbuilder'
            - 'unistoresvc_'
            - 'AcrSch2Svc'
    condition: 1 of selection_*
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: condition

1 of selection_*

Stage 1: selection_reg

selection_reg:
    CommandLine|contains|all:
        - 'Microsoft\Windows\CurrentVersion\Run'
        - 'C:\users\Public\'

Stage 2: selection_del

selection_del:
    CommandLine|contains|all:
        - 'del /s /f /q c:\'
        - '\*.bac'
        - '\*.bak'
        - '\*.bkf'

Stage 3: selection_net

selection_net:
    Image|endswith:
        - '\net.exe'
        - '\net1.exe'
    CommandLine|contains|all:
        - ' stop '
        - ' /y'
    CommandLine|contains:
        - 'samss'
        - 'audioendpointbuilder'
        - 'unistoresvc_'
        - 'AcrSch2Svc'

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
  • /y corpus 2 (sigma 2)
  • stop corpus 8 (sigma 6, splunk 2)
  • AcrSch2Svc corpus 2 (sigma 2)
  • C:\users\Public\ corpus 2 (sigma 2)
  • Microsoft\Windows\CurrentVersion\Run corpus 2 (sigma 2)
  • \*.bac
  • \*.bak
  • \*.bkf
  • audioendpointbuilder
  • del /s /f /q c:\
  • samss corpus 2 (sigma 2)
  • unistoresvc_
Imageends_with
  • \net.exe corpus 49 (sigma 49)
  • \net1.exe corpus 47 (sigma 47)