CVE-2017-2779

Summary

An exploitable memory corruption vulnerability exists in the RSRC segment parsing functionality of LabVIEW. A specially crafted VI file can cause an attacker controlled looping condition resulting in an arbitrary null write. An attacker controlled VI file can be used to trigger this vulnerability and can potentially result in code execution.

Tested Versions

LabVIEW 2016 version 16.0

Product URLs

http://www.ni.com/labview/

CVSSv3 Score

7.5 - CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

CWE

CWE-787: Out-of-bounds Write

Details

LabVIEW provides engineers a simple environment to build measurement or control systems. LabVIEW is used to abstract many of the low-level details of various hardware and signal-processing libraries into a single platform. It uses a graphical programming approach to achieve this goal.

Modules utilized in this vulnerability:

start end module name 03cc0000 03d76000 mgcore_SH_16_0 (export symbols) C:\Program Files\National Instruments\LabVIEW 2016\resource\mgcore_SH_16_0.dll Loaded symbol image file: C:\Program Files\National Instruments\LabVIEW 2016\resource\mgcore_SH_16_0.dll Image path: C:\Program Files\National Instruments\LabVIEW 2016\resource\mgcore_SH_16_0.dll Image name: mgcore_SH_16_0.dll Browse all global symbols functions data Timestamp: Wed Jun 08 10:00:01 2016 (57584F11) CheckSum: 000B192B ImageSize: 000B6000 File version: 16.0.0.49152

While opening a VI file, an RSRC segment can be parsed. An example of the beginning of this segment is shown below:

0:000> dc esi 0acf6690 43525352 03000a0d 4e49564c 5756424c RSRC....LVINLBVW 0acf66a0 d00b0000 eb020000 20000000 b00b0000 ........... .... 0acf66b0 00000000 00000000 20000000 34000000 ........... ...4 0acf66c0 d8020000 14000000 5253564c 00000000 ........LVSR.... 0acf66d0 00010000 47535452 00000000 14010000 ....RTSG........ 0acf66e0 73726576 00000000 28010000 504e4f43 vers.......(CONP 0acf66f0 00000000 3c010000 6976494c 00000000 .......<LIvi.... 0acf6700 50010000 57504442 00000000 64010000 ...PBDPW.......d

After parsing the RSRC segment into an internal RSRC struct, LabVIEW tries to clean up data handles created in this process. To begin this process, the loop counter is first extracted from the RSRC segment.

mgcore_SH_16_0!LVResFile::ClearAllDataHdls+0x18: .text:1001FF98 008 mov esi, [ecx+2Ch] // [0] ecx is beginning of segment (0xacf6690 above) .text:1001FF9B 008 add esi, ecx // [1] .text:1001FF9D 008 mov eax, [esi] // [2]

Extracted first is the offset to the loop counter [0]. This value is then added to the beginning of the RSRC segment [1]. This new address is accessed to extract the loop counter used for termination of the main loop for clearing data handles.

The loop responsible for clearing the data handles is below:

mgcore_SH_16_0!LVResFile::ClearAllDataHdls+0x30: .text:1001FFB0 loop_top: .text:1001FFB0 00C mov eax, [edx] // [4] edx is our current pointer (starting at 0xacf66d0 above) .text:1001FFB2 00C mov ecx, [edx-4] .text:1001FFB5 00C add eax, esi // [5] .text:1001FFB7 00C test ecx, ecx .text:1001FFB9 00C jl short dec_counter .text:1001FFBB 00C add eax, 10h .text:1001FFBE 00C inc ecx .text:1001FFBF 00C nop .text:1001FFC0 .text:1001FFC0 loop_inner: .text:1001FFC0 00C mov dword ptr [eax], 0 // [6] .text:1001FFC6 00C add eax, 14h .text:1001FFC9 00C sub ecx, 1 .text:1001FFCC 00C jnz short loop_inner .text:1001FFCE .text:1001FFCE dec_counter: .text:1001FFCE 00C add edx, 0Ch // [7] .text:1001FFD1 00C sub edi, 1 .text:1001FFD4 00C jnz short loop_top .text:1001FFD6 00C pop edi

The loop extracts the value under the current pointer [4] and adds it to the beginning of the segment [5]. This address is then cleared [6] and the pointer moves to the next section [7].

An attacker can control the loop counter as well as the offsets read from the RSRC struct used to calculate which address to clear, causing a write null anywhere situation. This null overwrite could potentially be leveraged into code execution.

Crash Information

0:000> r eax=57f416eb ebx=0b8be230 ecx=4c56494f edx=0bb1c1b0 esi=0bb1c084 edi=13ffffe9 eip=03d8ffc0 esp=0012d3d0 ebp=0012d3d8 iopl=0 nv up ei pl nz na po nc cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00010202 mgcore_SH_16_0!LVResFile::ClearAllDataHdls+0x40: 03d8ffc0 c70000000000 mov dword ptr [eax],0 ds:0023:57f416eb=???????? 0:000> !exploitable !exploitable 1.6.0.0 Exploitability Classification: EXPLOITABLE Recommended Bug Title: Exploitable - User Mode Write AV starting at mgcore_SH_16_0!LVResFile::ClearAllDataHdls+0x0000000000000040 (Hash=0x74591f62.0x054d4767) User mode write access violations that are not near NULL are exploitable.

Timeline

2017-01-25 - Vendor Disclosure

2017-08-29 - Public Release