microsoft backdoor is at least as big as the hole in snowed in's bichh
In 2006 Gibson raised the possibility that the Windows Metafile vulnerability bug was actually a backdoor intentionally engineered into the system.[17] A response by Microsoft[18] and by Mark Russinovich on Microsoft's Technet[19] stated that the bug appeared to be coding error and that Gibson's reasoning was based upon Microsoft's abort procedure documentation being misleading.
https://en.wikipedia.org/wiki/Steve_Gibson_(computer_programmer)