For strange reason, I cannot replace the old dumpbin.exe included in MASM32 with the latest on from VS 2012.
Here are the steps:
1. Check the dumpbin version in C:\masm32\bin
cd C:\masm32\bin
C:\masm32\bin\dumpbin.exe
Microsoft (R) COFF Binary File Dumper Version 5.12.8078
Copyright (C) Microsoft Corp 1992-1998. All rights reserved.
2. OK, it's the old one. Let's replace it with latest one from VS 2012
erase dumpbin.exe
C:\masm32\bin>copy "C:\Program Files\Microsoft Visual Studio 11.0\VC\bin\dumpbin.exe"
3. Run it
C:\masm32\bin\dumpbin.exe
Microsoft (R) COFF Binary File Dumper Version 5.12.8078
Copyright (C) Microsoft Corp 1992-1998. All rights reserved.
Still the same old version?

But if I run dumpbin from VS2012 command prompt:
C:\Program Files\Microsoft Visual Studio 11.0\VC\bin>dumpbin.exe
Microsoft (R) COFF/PE Dumper Version 11.00.50522.1
Copyright (C) Microsoft Corporation. All rights reserved.
I did this several times, and it didn't change at all. But I successfully replaced the old ml.exe with the latest one (ml.exe v11.00.50522.1)