SEC Consult Vulnerability Lab Security Advisory < 20130313-0 >
=======================================================================
              title: QlikView Desktop Client Integer Overflow
            product: QlikView Desktop Client
 vulnerable version: 11.00 SR2
      fixed version: 11.20 SR1
                CVE: 
             impact: High
           homepage: http://www.qlikview.com/
              found: 2012-10-22
                 by: A. Antukh, M. Lucinskij
                     SEC Consult Vulnerability Lab
                     https://www.sec-consult.com 
=======================================================================

Vendor description:
-------------------
"QlikView is a new kind of business intelligence software that changes 
your world. Its BI software that lets you stop guessing and start knowing 
how to make faster, smarter decisions."

Source: http://www.qlikview.com/us/explore


Vulnerability overview/description:
-----------------------------------
An integer overflow vulnerability exists in the .qvw file format parser. 
A parameter that is responsible for the section length is checked improperly,
which causes a heap overflow if any value bigger than 0x80000000 is set. 

Successful exploitation of this vulnerability could result in an arbitrary 
code execution within the QlikView Desktop client.



Vulnerability details:
----------------------
The .qvw file is divided into several sections with a specified delimiter.
Among others, there is a parameter which is responsible for defining the
section length. On the hex listing below it's the DWORD A4 00 00 00 (address
315EF)

000315B0:  00 00 01 00-00 00 0E 23-23 23 23 23-23 23 23 23
000315C0:  23 23 23 23-23 01 2E 00-00 00 00 00-00 00 00 00
000315D0:  00 00 00 00-00 00 00 00-00 00 00 00-00 00 00 03
000315E0:  00 00 00 00-00 00 00 90-02 00 00 00-00 04 00 A4
000315F0:  00 00 00 78-9C 3D CC CB-4A 02 50 14-86 D1 1F 47

If by any reasons the value is bigger than the actual size of the section,
an error is handled by a C++ EH and a message "Document failed to load" is
shown. The check condition can be seen here:

.text:00D6BD66                 mov     eax, [edi+28h]
.text:00D6BD69                 mov     ebx, [eax]      ; here is the length parameter
.text:00D6BD6B                 add     eax, 4
.text:00D6BD6E                 mov     [edi+28h], eax
.text:00D6BD71                 cmp     ebx, [ebp+var_14]
.text:00D6BD74                 jg      loc_D6BBAC      ; check if the parameter value 
                                                         is bigger than actual length

However, the comparison operates with a signed number and doesn't check if it's
less than zero. In other words, if an attacker supplies a DWORD bigger than
0x80000000, the jump will not be taken (as the number will be considered as 
negative), causing an integer overflow. After that, the length parameter is used 
as the DstSize argument to the CArchive::Read function:

.text:00D6BD7A                 mov     eax, [ebp+Dst]
.text:00D6BD7D                 push    ebx             ; DstSize
.text:00D6BD7E                 push    eax             ; Dst
.text:00D6BD7F                 mov     ecx, edi
.text:00D6BD81                 call    ?Read@CArchive@@QAEIPAXI@Z ; CArchive::Read(void *,uint)

A large amount of data is read. It is used later to fill the created Archive
whose size is 0x8000:
 
.text:00B26207                 push    0
.text:00B26209                 push    8000h
.text:00B2620E                 push    1
.text:00B26210                 lea     eax, [ebp+var_60]
.text:00B26213                 push    eax
.text:00B26214                 lea     ecx, [ebp+var_A8]
.text:00B2621A                 call    ??0CArchive@@QAE@PAVCFile@@IHPAX@Z ; 
                                                     CArchive::CArchive(CFile *,uint,int,void *)

This results in the controlled address being overwritten with the controlled
value.

.text:009F3092                 mov     ecx, [esi]
.text:009F3094                 mov     edx, [esi+4]
.text:009F3097                 mov     [ecx+4], edx    ; here the error occurs;
.text:009F3097                                         ; trying to write at non-existing address

An extract from a debugger with the occurence of the error is presented below.

eax=04735f14 ebx=00000000 ecx=bbbbbbb7 edx=aaaaaaa6 esi=04b2fbc0 edi=04735f10
eip=01723097 esp=003527f8 ebp=00352818 iopl=0         nv up ei pl nz ac pe nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00010216
Qv+0x5f3097:
01723097 895104          mov     dword ptr [ecx+4],edx ds:002b:bbbbbbbb=????????



Vulnerable / tested versions:
-----------------------------
The vulnerability has been verified to exist in QlikView 11.00 SR2, 
which was the most recent version at the time of discovery.



Vendor contact timeline:
------------------------
2012-11-08: Contacted vendor through support@qlikview.com
2012-11-12: Initial vendor response - issue will be verified
2012-12-13: Vulnerability is confirmed and reproduced by the vendor
2013-03-06: Vendor releases patch / new version
2013-03-13: Coordinated disclosure


Solution:
---------
Update to QlikView 11.20 SR1 


Workaround:
-----------
None


Advisory URL:
-------------
https://www.sec-consult.com/en/Vulnerability-Lab/Advisories.htm


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EOF A. Antukh / @2013