The ESXi host must enable strict x509 verification for SSL syslog endpoints.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-256437	SRG-OS-000480-VMM-002000	ESXI-70-000085	SV-256437r959010_rule	2025-02-11	1

Description
When sending syslog data to a remote host via SSL, the ESXi host is presented with the endpoint's SSL server certificate. In addition to trust verification, configured elsewhere, this "x509-strict" option performs additional validity checks on CA root certificates during verification. These checks are generally not performed (CA roots are inherently trusted) and might cause incompatibilities with existing, misconfigured CA roots. The NIAP requirements in the Virtualization Protection Profile and Server Virtualization Extended Package, however, require even CA roots to pass validations.

Description

When sending syslog data to a remote host via SSL, the ESXi host is presented with the endpoint's SSL server certificate. In addition to trust verification, configured elsewhere, this "x509-strict" option performs additional validity checks on CA root certificates during verification. These checks are generally not performed (CA roots are inherently trusted) and might cause incompatibilities with existing, misconfigured CA roots. The NIAP requirements in the Virtualization Protection Profile and Server Virtualization Extended Package, however, require even CA roots to pass validations.

ℹ️ Check
If SSL is not used for the syslog target, this is not applicable. From an ESXi shell, run the following command: # esxcli system syslog config get\|grep 509 or From a PowerCLI command prompt while connected to the ESXi host, run the following commands: $esxcli = Get-EsxCli -v2 $esxcli.system.syslog.config.get.invoke()\|Select StrictX509Compliance Expected result: Strict X509Compliance: true If the output does not match the expected result, this is a finding.

ℹ️ Check

If SSL is not used for the syslog target, this is not applicable. From an ESXi shell, run the following command: # esxcli system syslog config get|grep 509 or From a PowerCLI command prompt while connected to the ESXi host, run the following commands: $esxcli = Get-EsxCli -v2 $esxcli.system.syslog.config.get.invoke()|Select StrictX509Compliance Expected result: Strict X509Compliance: true If the output does not match the expected result, this is a finding.

✔️ Fix
From an ESXi shell, run the following commands: # esxcli system syslog config set --x509-strict="true" # esxcli system syslog reload or From a PowerCLI command prompt while connected to the ESXi host, run the following commands: $esxcli = Get-EsxCli -v2 $arguments = $esxcli.system.syslog.config.set.CreateArgs() $arguments.x509strict = $true $esxcli.system.syslog.config.set.Invoke($arguments) $esxcli.system.syslog.reload.Invoke()

✔️ Fix

From an ESXi shell, run the following commands: # esxcli system syslog config set --x509-strict="true" # esxcli system syslog reload or From a PowerCLI command prompt while connected to the ESXi host, run the following commands: $esxcli = Get-EsxCli -v2 $arguments = $esxcli.system.syslog.config.set.CreateArgs() $arguments.x509strict = $true $esxcli.system.syslog.config.set.Invoke($arguments) $esxcli.system.syslog.reload.Invoke()