A sticky bit must be set on all public directories to prevent unauthorized and unintended information transferred via shared system resources.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-75811	UBTU-16-030070	SV-90491r4_rule		Medium

Description
Preventing unauthorized information transfers mitigates the risk of information, including encrypted representations of information, produced by the actions of prior users/roles (or the actions of processes acting on behalf of prior users/roles) from being available to any current users/roles (or current processes) that obtain access to shared system resources (e.g., registers, main memory, hard disks) after those resources have been released back to information systems. The control of information in shared resources is also commonly referred to as object reuse and residual information protection. This requirement generally applies to the design of an information technology product, but it can also apply to the configuration of particular information system components that are, or use, such products. This can be verified by acceptance/validation processes in DoD or other government agencies. There may be shared resources with configurable protections (e.g., files in storage) that may be assessed on specific information system components.

Description

Preventing unauthorized information transfers mitigates the risk of information, including encrypted representations of information, produced by the actions of prior users/roles (or the actions of processes acting on behalf of prior users/roles) from being available to any current users/roles (or current processes) that obtain access to shared system resources (e.g., registers, main memory, hard disks) after those resources have been released back to information systems. The control of information in shared resources is also commonly referred to as object reuse and residual information protection. This requirement generally applies to the design of an information technology product, but it can also apply to the configuration of particular information system components that are, or use, such products. This can be verified by acceptance/validation processes in DoD or other government agencies. There may be shared resources with configurable protections (e.g., files in storage) that may be assessed on specific information system components.

STIG	Date
Canonical Ubuntu 16.04 LTS Security Technical Implementation Guide	2018-07-18

Details

Check Text ( C-75499r4_chk )
Verify that all world writable directories have the sticky bit set. Check to see that all world writable directories have the sticky bit set by running the following command: # sudo find / -type d \( -perm -0002 -a ! -perm -1000 \) -print 2>/dev/null drwxrwxrwxt 7 root root 4096 Jul 26 11:19 /tmp If any of the returned directories are world writable and do not have the sticky bit set, this is a finding.

Check Text ( C-75499r4_chk )

Verify that all world writable directories have the sticky bit set.

Check to see that all world writable directories have the sticky bit set by running the following command:

# sudo find / -type d \( -perm -0002 -a ! -perm -1000 \) -print 2>/dev/null

drwxrwxrwxt 7 root root 4096 Jul 26 11:19 /tmp

If any of the returned directories are world writable and do not have the sticky bit set, this is a finding.

Fix Text (F-82441r2_fix)
Configure all world writable directories have the sticky bit set to prevent unauthorized and unintended information transferred via shared system resources. Set the sticky bit on all world writable directories using the command, replace "[World-Writable Directory]" with any directory path missing the sticky bit: # sudo chmod 1777 [World-Writable Directory]