The 10 Immutable Laws of Security from Microsoft TechNet:
Law #1: If a bad guy can persuade you to run his program on your computer, it’s not your computer anymore- Law #2: If a bad guy can alter the operating system on your computer, it’s not your computer anymore
 - Law #3: If a bad guy has unrestricted physical access to your computer, it’s not your computer anymore
 - Law #4: If you allow a bad guy to upload programs to your website, it’s not your website any more
 - Law #5: Weak passwords trump strong security
 - Law #6: A computer is only as secure as the administrator is trustworthy
 - Law #7: Encrypted data is only as secure as the decryption key
 - Law #8: An out of date virus scanner is only marginally better than no virus scanner at all
 - Law #9: Absolute anonymity isn’t practical, in real life or on the Web
 - Law #10: Technology is not a panacea
 
Law #1: If a bad guy can persuade you to run his program on your computer, it’s not your computer anymore