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 [email protected]
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