Host must block network traffic by default

MediumLevel 1Automatedvmware

Description

By default, the host is configured to block all incoming and outgoing network traffic, except for the traffic pertaining to services enabled in the host security profile. This configuration is pivotal in reducing the attack surface and averting unauthorized access to the host. The audit runs esxcli network firewall get and requires "Enabled: true" and "Default Action: DROP"; review enabled rulesets as well. Runs in the ESXi Shell (busybox sh) as root.

How it is checked

Audit method: Shell command

shell

out=$(esxcli network firewall get 2>/dev/null) || exit 1
a=$(printf '%s\n' "$out" | sed -n 's/^ *Default Action: *//p' | head -n 1)
e=$(printf '%s\n' "$out" | sed -n 's/^ *Enabled: *//p' | head -n 1)
[ "$a" = DROP ] && [ "$e" = true ] && echo compliant || echo "firewall enabled=$e default action=$a"

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

1. Enable the ESXi firewall if disabled and disable unnecessary rulesets. 2. Use: esxcli network firewall set --enabled true 3. Configure only the required rulesets for documented services.

Properties

Operating systems: Any
Tags: vmwareesxinetwork
Reference: CIS VMware ESXi 9.0 Benchmark v1.0.0 - 5.2 Host must block network traffic by default

Check this host

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

shell

tmaegis scan --target vmware