Ensure address space layout randomization (ASLR) is enabled

MediumLevel 1Automatedlinux

Description

Address space layout randomization (ASLR) is an exploit mitigation technique which randomly arranges the address space of key data areas of a process.

How it is checked

Audit method: Shell command

shell

chk() { p=$1; allowed=" $2 "; case $p in net.ipv6.*) [ -d /proc/sys/net/ipv6 ] || return 0;; esac; v=$(sysctl -n "$p" 2>/dev/null) || { echo "$p: not available"; return 1; }; case "$allowed" in *" $v "*) ;; *) echo "$p is $v (running)"; return 1;; esac; sd=$(readlink -e /lib/systemd/systemd-sysctl || readlink -e /usr/lib/systemd/systemd-sysctl); f=$("$sd" --cat-config 2>/dev/null | grep -Po "^\h*${p//./\.}\h*=\h*\K\H+" | tail -n1); [ -n "$f" ] || { echo "$p is not set in any sysctl configuration file"; return 1; }; case "$allowed" in *" $f "*) ;; *) echo "$p is $f in configuration"; return 1;; esac; }; if chk kernel.randomize_va_space 2; then echo compliant; fi

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

Set the following parameter in /etc/sysctl.conf or a /etc/sysctl.d/* file: kernel.randomize_va_space = 2 Run the following command to set the active kernel parameter: # sysctl -w kernel.randomize_va_space=2

Properties

Operating systems: alinux-2
Tags: cis-convertedkernellinuxsysctl
Reference: CIS Aliyun Linux 2 Benchmark v1.0.0 ARCHIVE - 1.5.2

Check this host

Run this on a machine you are allowed to audit. The scan is read-only.

shell

tmaegis scan --target linux