The values the debug version of CRT memory manager fills memory with.
dbgheap.c:

static unsigned char _bNoMansLandFill = 0xFD;   /* fill no-man’s land with this */
static unsigned char _bDeadLandFill   = 0xDD;   /* fill free objects with this */
static unsigned char _bCleanLandFill  = 0xCD;   /* fill new objects with this */
static unsigned char _bAlignLandFill  = 0xBD;   /* fill no-man’s land for
aligned routines */

Additionally, debug compilation (optimization turned off?) produces code which uses 0xCC fill to initialize variables on stack and