>>12
What backdoor are you talking about? The standard c libraries are come with the source from MS. The workings of the linker are publicly known and you can use a lot of tools to examine the generated binaries. If you say there's a bug in the code, then it would have been found/exploited ages ago. On bugs in libraries, one of Borland's older libc's comes with a floating point division error which can be exploited to crash an application.