TMA-VMWARE-5.1
Host firewall must only allow traffic from authorized networks
Description
The host's firewall is designed to block all incoming and outgoing network traffic by default, unless exceptions are explicitly made, thus minimizing the attack surface and barring unauthorized access. The firewall settings, while simplistic, are akin to router ACLs, and might require reflexive rules to be configured for certain network scenarios. The audit lists enabled firewall rulesets (esxcli network firewall ruleset list) and fails any whose allowed IP list (ruleset allowedip list) is All; confirm the configured ranges are the authorized networks. Runs in the ESXi Shell (busybox sh) as root.
How it is checked
Audit method: Shell command
en=$(esxcli network firewall ruleset list 2>/dev/null | awk 'NR > 2 && $2 == "true" {print $1}') || exit 1
all=$(esxcli network firewall ruleset allowedip list 2>/dev/null | awk 'NR > 2 && $2 == "All" {print $1}') || exit 1
bad=''
for r in $en; do for a in $all; do [ "$r" = "$a" ] && bad="$bad $r"; done; done
[ -z "$bad" ] && echo compliant || echo "enabled rulesets allowing all IPs:$bad"- Expected output
compliant
How it is fixed
Fix method: Guidance or infrastructure patch
To properly restrict access to services running on an ESXi host, perform the following from the vSphere web client: 1. Select a host 2. Click Configure then expand System then select Firewall. 3. Click Edit to view services which are enabled (indicated by a check). 4. For each enabled service, (e.g., ssh, vSphere Web Access, http client) provide a list of allowed IP addresses. 5. Click OK.
Properties
- Operating systems
- Any
- Tags
- vmwareesxinetwork
- Reference
- CIS VMware ESXi 8.0 Benchmark v1.4.0 - 5.1 Host firewall must only allow traffic from authorized networks
Check this host
Run this on a machine you are allowed to audit. The scan is read-only.
tmaegis scan --target vmware