Episode 36 — Linux Permissions: UGO, SUID/SGID, and Sticky Bits
Permissions are at the heart of Linux security, and this episode breaks down how the User, Group, and Other (UGO) model governs every file interaction. You’ll learn how read, write, and execute bits combine to create granular control, and why understanding numeric (octal) notation makes permissions easier to visualize. We also cover the significance of ownership—how chown and chmod commands enforce structure—and why misaligned permissions are often the root cause of privilege escalation. The conversation moves from concept to application, showing how default umask values, inheritance, and directory permissions interact to shape real-world behavior.
Listeners will also explore special permissions—Set User ID (SUID), Set Group ID (SGID), and the sticky bit—and how they enable controlled privilege elevation or protect shared directories. We explain where these features are essential (like in /usr/bin/passwd) and where they create unnecessary risk. By walking through examples of secure versus insecure configurations, the episode teaches not just memorization but reasoning—why certain settings exist, how attackers abuse them, and how defenders detect and remediate misuse. These lessons apply directly to GSEC exam objectives and to daily administrative work in multi-user Linux environments. Produced by BareMetalCyber.com, where you’ll find more cyber audio courses, books, and information to strengthen your educational path. Also, if you want to stay up to date with the latest news, visit DailyCyber.News for a newsletter you can use, and a daily podcast you can commute with.
