Linux File Permissions Cheat Sheet

1 min read
#linux #permissions #privilege-escalation
Table of Contents

Permission Bits

PermissionFileDirectory
r (4)Read contentList contents
w (2)Modify contentCreate/delete files
x (1)ExecuteEnter directory

chmod Examples

chmod 755 file.sh    # rwxr-xr-x
chmod u+s binary     # Set SUID
chmod g+s dir/       # Set SGID
chmod +t dir/        # Set sticky bit

Special Permissions

  • SUID (4) — File executes as owner
  • SGID (2) — File executes as group / new files inherit group
  • Sticky Bit (1) — Only owner can delete files in directory

Finding SUID Binaries

find / -perm -4000 -type f 2>/dev/null

PrivEsc

SUID binaries are a common Linux privilege escalation vector. Always check GTFOBins for known exploits.
zer0arc4

zer0arc4

Cybersecurity Student | Penetration Testing & Red Teaming Enthusiast

Documenting my journey through cybersecurity, penetration testing, CTFs, research, and tool development.

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