you can search in registry.Actually I do'nt have vs2012 but I have vs2010.
There are 3 different (but very similar) registry keys for each of the 3 platform packages. Each key has a DWORD value called “Installed” with a value of 1.
HKLM\SOFTWARE\Microsoft\VisualStudio\10.0\VC\VCRedist\x86
HKLM\SOFTWARE\Microsoft\VisualStudio\10.0\VC\VCRedist\x64
HKLM\SOFTWARE\Microsoft\VisualStudio\10.0\VC\VCRedist\ia64
You can use registry function for that......