Serv-U Exploitation CVE-2021-35211 by DEV-0322

Detects patterns as noticed in exploitation of Serv-U CVE-2021-35211 vulnerability by threat group DEV-0322

Detection logic

selection_whoami

CommandLine|contains: whoami

selection_cmd_1

CommandLine|contains:
  - ./Client/Common/
  - .\Client\Common\

selection_cmd_2

CommandLine|contains: C:\Windows\Temp\Serv-U.bat

Condition

selection_whoami and 1 of selection_cmd*

Raw YAML

title: Serv-U Exploitation CVE-2021-35211 by DEV-0322
id: 75578840-9526-4b2a-9462-af469a45e767
status: test
description: Detects patterns as noticed in exploitation of Serv-U CVE-2021-35211 vulnerability by threat group DEV-0322
references:
    - https://www.microsoft.com/security/blog/2021/07/13/microsoft-discovers-threat-actor-targeting-solarwinds-serv-u-software-with-0-day-exploit/
author: Florian Roth (Nextron Systems)
date: 2021-07-14
modified: 2022-12-18
tags:
    - attack.persistence
    - attack.t1136.001
    - cve.2021-35211
    - detection.emerging-threats
    # - threat_group.DEV-0322
logsource:
    category: process_creation
    product: windows
detection:
    selection_whoami:
        CommandLine|contains: 'whoami'
    selection_cmd_1:
        CommandLine|contains:
            - './Client/Common/'
            - '.\Client\Common\'
    selection_cmd_2:
        CommandLine|contains: 'C:\Windows\Temp\Serv-U.bat'
    condition: selection_whoami and 1 of selection_cmd*
falsepositives:
    - Unlikely
level: critical