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GSEC · Question #20

What would the file permission example "rwsr-sr-x" translate to in absolute mode?

The correct answer is B. 6755. The permission string 'rwsr-sr-x' encodes SUID and SGID special bits plus standard read/write/execute permissions, translating to absolute octal mode 6755.

Linux and Cryptography

Question

What would the file permission example "rwsr-sr-x" translate to in absolute mode?

Options

  • A1755
  • B6755
  • C6645
  • D1644

How the community answered

(36 responses)
  • A
    3% (1)
  • B
    83% (30)
  • C
    8% (3)
  • D
    6% (2)

Why each option

The permission string 'rwsr-sr-x' encodes SUID and SGID special bits plus standard read/write/execute permissions, translating to absolute octal mode 6755.

A1755

1755 represents the sticky bit (value 1) with rwxr-xr-x permissions; the sticky bit appears as 't' in the others execute position, not 's' in owner and group positions.

B6755Correct

The symbolic string breaks into owner 'rws' (read+write+execute with SUID = 7), group 'r-s' (read+execute with SGID = 5), and others 'r-x' (read+execute = 5). The lowercase 's' in the owner execute position indicates the SUID bit (value 4) and the 's' in the group execute position indicates the SGID bit (value 2), producing a special-bit prefix of 6. Combined, this yields 6755 in absolute octal notation.

C6645

6645 would imply SUID+SGID with rw-r--r-x permissions, but the lowercase 's' in the owner position confirms the execute bit is set, making the owner octet 7 not 6.

D1644

1644 represents the sticky bit with rw-r--r-- permissions, which matches neither the SUID+SGID special bits nor the execute permissions visible in the symbolic string.

Concept tested: Linux SUID SGID special permission bits absolute octal mode

Source: https://www.man7.org/linux/man-pages/man1/chmod.1.html

Topics

#setuid#setgid#octal permissions#special permission bits

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