Vulnerability Discussion

Some adversaries launch attacks with the intent of executing code in non-executable regions of memory or in memory locations that are prohibited. Security safeguards employed to protect memory include, for example, data execution prevention and address space layout randomization. Data execution prevention safeguards can either be hardware-enforced or software-enforced with hardware providing the greater strength of mechanism.

Examples of attacks are buffer overflow attacks.

Check

Verify the Ubuntu operating system implements address space layout randomization (ASLR).

Check that ASLR is configured on the system with the following command:

# sudo sysctl kernel.randomize_va_space

kernel.randomize_va_space = 2

Verify the kernel parameter "randomize_va_space" is set to 2 with the following command:

# cat /proc/sys/kernel/randomize_va_space

2

If "kernel.randomize_va_space" is not set to 2, this is a finding.

Check the saved value of the kernel.randomize_va_space variable is not different from 2.

# sudo egrep -R "^kernel.randomize_va_space=[^2]" /etc/sysctl.conf /etc/sysctl.d

If this returns a result, this is a finding.

Fix

Set the "kernel.randomize_va_space" entry found in the "/etc/sysctl.conf" file to a value of "2".

After the line has been modified the kernel settings from all system configuration files must be reloaded; before any of the changes will take effect.

Run the following command to reload all of the kernel system configuration files:

# sudo sysctl --system