Virtual machines must remove unnecessary USB/XHCI devices

MediumLevel 1Automatedvmware

Description

Removing unnecessary devices from virtual machines minimizes the attack surface and reduces potential pathways for data exfiltration or unauthorized data capture. This practice aligns with the principle of least functionality, ensuring that VMs have only the essential components required to perform their designated functions. Expected: usb.present / usb_xhci.present absent or "FALSE". The audit parses every .vmx file under /vmfs/volumes/ on the host and lists the VMs that do not comply; it passes when none are found (or no VMs exist). Runs in the ESXi Shell (busybox sh) as root.

How it is checked

Audit method: Shell command

shell

command -v find >/dev/null 2>&1 || exit 1
out=$(find /vmfs/volumes/ -maxdepth 3 -type f -name '*.vmx' 2>/dev/null | while IFS= read -r f; do
  awk -v KEYRE='^usb(_xhci)?[.]present$' -v MODE='not' -v VAL='TRUE' 'BEGIN { re = tolower(KEYRE) }
{ line = $0; sub(/^[ \t]+/, "", line); i = index(line, "="); if (i == 0) next
  k = tolower(substr(line, 1, i - 1)); sub(/[ \t]+$/, "", k)
  v = substr(line, i + 1); sub(/^[ \t]*"?/, "", v); sub(/"?[ \t\r]*$/, "", v); v = tolower(v)
  if (k ~ re) { seen = 1; if (MODE == "not" && v == tolower(VAL)) bad = bad " " k "=" v
                else if (MODE != "not" && MODE != "ge" && v != tolower(VAL)) bad = bad " " k "=" v
                else if (MODE == "ge" && (v + 0) < (VAL + 0)) bad = bad " " k "=" v } }
END { if ((MODE == "eq" || MODE == "ge") && !seen) bad = " " KEYRE " not set"
      if (bad != "") print FILENAME ":" bad }' "$f"
done)
[ -z "$out" ] && echo compliant || printf '%s\n' "$out" | head -n 25

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

To disconnect all USB devices from VMs, run the following PowerCLI command: # Remove all USB Devices attached to VMs Get-VM | Get-USBDevice | Remove-USBDevice The VM will need to be powered off for this change to take effect.

Properties

Operating systems: Any
Tags: vmwareesxivirtual-machine
Reference: CIS VMware ESXi 9.0 Benchmark v1.0.0 - 7.12 Virtual machines must remove unnecessary USB/XHCI devices

Check this host

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

shell

tmaegis scan --target vmware