Virtual machines (VMs) must have shared salt values disabled.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-258712	VMCH-80-000199	SV-258712r959010_rule		Low

Description
When salting is enabled (Mem.ShareForceSalting=1 or 2) to share a page between two virtual machines, both salt and the content of the page must be same. A salt value is a configurable advanced option for each virtual machine. The salt values can be specified manually in the virtual machine's advanced settings with the new option "sched.mem.pshare.salt". If this option is not present in the virtual machine's advanced settings, the value of the "vc.uuid" option is taken as the default value. Because the "vc.uuid" is unique to each virtual machine, by default Transparent Page Sharing (TPS) happens only among the pages belonging to a particular virtual machine (Intra-VM).

Description

When salting is enabled (Mem.ShareForceSalting=1 or 2) to share a page between two virtual machines, both salt and the content of the page must be same. A salt value is a configurable advanced option for each virtual machine. The salt values can be specified manually in the virtual machine's advanced settings with the new option "sched.mem.pshare.salt". If this option is not present in the virtual machine's advanced settings, the value of the "vc.uuid" option is taken as the default value. Because the "vc.uuid" is unique to each virtual machine, by default Transparent Page Sharing (TPS) happens only among the pages belonging to a particular virtual machine (Intra-VM).

STIG	Date
VMware vSphere 8.0 Virtual Machine Security Technical Implementation Guide	2024-07-11

Details

Check Text ( C-62452r933195_chk )
For each virtual machine do the following: From the vSphere Client, right-click the Virtual Machine and go to Edit Settings >> Advanced Parameters. Verify the "sched.mem.pshare.salt" setting does not exist. or From a PowerCLI command prompt while connected to the ESXi host or vCenter server, run the following command: Get-VM "VM Name" \| Get-AdvancedSetting -Name sched.mem.pshare.salt If the virtual machine advanced setting "sched.mem.pshare.salt" exists, this is a finding.

Check Text ( C-62452r933195_chk )

For each virtual machine do the following:

From the vSphere Client, right-click the Virtual Machine and go to Edit Settings >> Advanced Parameters.

Verify the "sched.mem.pshare.salt" setting does not exist.

or

From a PowerCLI command prompt while connected to the ESXi host or vCenter server, run the following command:

Get-VM "VM Name" | Get-AdvancedSetting -Name sched.mem.pshare.salt

If the virtual machine advanced setting "sched.mem.pshare.salt" exists, this is a finding.

Fix Text (F-62361r933196_fix)
For each virtual machine do the following: From the vSphere Client, right-click the Virtual Machine and go to Edit Settings >> Advanced Parameters. Delete the "sched.mem.pshare.salt" setting. or From a PowerCLI command prompt while connected to the ESXi host or vCenter server, run the following command: Get-VM "VM Name" \| Get-AdvancedSetting -Name sched.mem.pshare.salt \| Remove-AdvancedSetting Note: The VM must be powered off to configure the advanced settings through the vSphere Client. Therefore, it is recommended to configure these settings with PowerCLI as this can be done while the VM is powered on. Settings do not take effect via either method until the virtual machine is cold started, not rebooted.

Fix Text (F-62361r933196_fix)

For each virtual machine do the following:

From the vSphere Client, right-click the Virtual Machine and go to Edit Settings >> Advanced Parameters.

Delete the "sched.mem.pshare.salt" setting.

or

From a PowerCLI command prompt while connected to the ESXi host or vCenter server, run the following command:

Get-VM "VM Name" | Get-AdvancedSetting -Name sched.mem.pshare.salt | Remove-AdvancedSetting

Note: The VM must be powered off to configure the advanced settings through the vSphere Client. Therefore, it is recommended to configure these settings with PowerCLI as this can be done while the VM is powered on. Settings do not take effect via either method until the virtual machine is cold started, not rebooted.