James Bond, while working on a top-secret case for many weeks in deep enemy territory, finally collected and stored lots of critical files on his tight-security Linux system. Even though the system was on the internet, no unauthorized user could ever break-in and access the files marked For-Your-Eyes-Only. He then secretly contacted his group (M, Q, Moneypenny, Etc) to process the files. After 30 minutes, they all responded that the system said "No Access". So Bond tried to access the files, and true enough, the system said "No Access".
Meanwhile some other folks (probably double-agents or hackers from SPECTRE) had read all the files. Bond realised that he had made a big mistake, out of habit.
What mistake did Bond commit, that all his work was leaked so easily ?
FYI 1 : Here the tags for this question are important.
FYI 2 : He quickly recovered from this situation to prevent further leakage.