The vCenter Server for Windows must only send NetFlow traffic to authorized collectors.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-94743	VCWN-65-000016	SV-104573r1_rule		Medium

Description
The distributed virtual switch can export NetFlow information about traffic crossing the switch. NetFlow exports are not encrypted and can contain information about the virtual network making it easier for a MitM attack to be executed successfully. If NetFlow export is required, verify that all NetFlow target IP's are correct.

STIG	Date
VMware vSphere 6.5 vCenter Server for Windows Security Technical Implementation Guide	2020-03-27

Details

Check Text ( C-93933r1_chk )
To view NetFlow Collector IPs configured on distributed switches: From the vSphere Web Client go to Networking >> Select a distributed switch >> Configure >> Settings >> NetFlow. View the NetFlow pane and verify any collector IP addresses are valid and in use for troubleshooting. or From a PowerCLI command prompt while connected to the vCenter server run the following command: Get-VDSwitch \| select Name,@{N="NetFlowCollectorIPs";E={$_.ExtensionData.config.IpfixConfig.CollectorIpAddress}} ---- To view if NetFlow is enabled on any distributed port groups: From the vSphere Web Client go to Networking >> Select a distributed port group >> Manage >> Settings >> Policies. Go to Monitoring and view the NetFlow status. or From a PowerCLI command prompt while connected to the vCenter server run the following command: Get-VDPortgroup \| Select Name,VirtualSwitch,@{N="NetFlowEnabled";E={$_.Extensiondata.Config.defaultPortConfig.ipfixEnabled.Value}} If NetFlow is configured and the collector IP is not known and is not enabled temporarily for troubleshooting purposes, this is a finding.

Check Text ( C-93933r1_chk )

To view NetFlow Collector IPs configured on distributed switches:
From the vSphere Web Client go to Networking >> Select a distributed switch >> Configure >> Settings >> NetFlow. View the NetFlow pane and verify any collector IP addresses are valid and in use for troubleshooting.

or

From a PowerCLI command prompt while connected to the vCenter server run the following command:
Get-VDSwitch | select Name,@{N="NetFlowCollectorIPs";E={$_.ExtensionData.config.IpfixConfig.CollectorIpAddress}}
----
To view if NetFlow is enabled on any distributed port groups:
From the vSphere Web Client go to Networking >> Select a distributed port group >> Manage >> Settings >> Policies. Go to Monitoring and view the NetFlow status.

or

From a PowerCLI command prompt while connected to the vCenter server run the following command:
Get-VDPortgroup | Select Name,VirtualSwitch,@{N="NetFlowEnabled";E={$_.Extensiondata.Config.defaultPortConfig.ipfixEnabled.Value}}

If NetFlow is configured and the collector IP is not known and is not enabled temporarily for troubleshooting purposes, this is a finding.

Fix Text (F-100861r1_fix)
To remove collector IPs do the following: From the vSphere Web Client go to Networking >> Select a distributed switch >> Configure >> Settings >> NetFlow. Click edit and remove any unknown collector IPs. or From a PowerCLI command prompt while connected to the vCenter server run the following commands: $dvs = Get-VDSwitch dvswitch \| Get-View ForEach($vs in $dvs){ $spec = New-Object VMware.Vim.VMwareDVSConfigSpec $spec.configversion = $vs.Config.ConfigVersion $spec.IpfixConfig = New-Object VMware.Vim.VMwareIpfixConfig $spec.IpfixConfig.CollectorIpAddress = "" $spec.IpfixConfig.CollectorPort = "0" $spec.IpfixConfig.ActiveFlowTimeout = "60" $spec.IpfixConfig.IdleFlowTimeout = "15" $spec.IpfixConfig.SamplingRate = "0" $spec.IpfixConfig.InternalFlowsOnly = $False $vs.ReconfigureDvs_Task($spec) } Note: This will reset the NetFlow collector configuration back to the defaults. To disable NetFlow on a distributed port group do the following: From the vSphere Web Client go to Networking >> Select a distributed port group >> Manage >> Settings >> Policies. Go to Monitoring and change NetFlow to disabled. or From a PowerCLI command prompt while connected to the vCenter server run the following commands: $pgs = Get-VDPortgroup \| Get-View ForEach($pg in $pgs){ $spec = New-Object VMware.Vim.DVPortgroupConfigSpec $spec.configversion = $pg.Config.ConfigVersion $spec.defaultPortConfig = New-Object VMware.Vim.VMwareDVSPortSetting $spec.defaultPortConfig.ipfixEnabled = New-Object VMware.Vim.BoolPolicy $spec.defaultPortConfig.ipfixEnabled.inherited = $false $spec.defaultPortConfig.ipfixEnabled.value = $false $pg.ReconfigureDVPortgroup_Task($spec) }

Fix Text (F-100861r1_fix)

To remove collector IPs do the following:
From the vSphere Web Client go to Networking >> Select a distributed switch >> Configure >> Settings >> NetFlow. Click edit and remove any unknown collector IPs.

or

From a PowerCLI command prompt while connected to the vCenter server run the following commands:
$dvs = Get-VDSwitch dvswitch | Get-View
ForEach($vs in $dvs){
$spec = New-Object VMware.Vim.VMwareDVSConfigSpec
$spec.configversion = $vs.Config.ConfigVersion
$spec.IpfixConfig = New-Object VMware.Vim.VMwareIpfixConfig
$spec.IpfixConfig.CollectorIpAddress = ""
$spec.IpfixConfig.CollectorPort = "0"
$spec.IpfixConfig.ActiveFlowTimeout = "60"
$spec.IpfixConfig.IdleFlowTimeout = "15"
$spec.IpfixConfig.SamplingRate = "0"
$spec.IpfixConfig.InternalFlowsOnly = $False
$vs.ReconfigureDvs_Task($spec)
}

Note: This will reset the NetFlow collector configuration back to the defaults.

To disable NetFlow on a distributed port group do the following:
From the vSphere Web Client go to Networking >> Select a distributed port group >> Manage >> Settings >> Policies. Go to Monitoring and change NetFlow to disabled.

or

From a PowerCLI command prompt while connected to the vCenter server run the following commands:
$pgs = Get-VDPortgroup | Get-View
ForEach($pg in $pgs){
$spec = New-Object VMware.Vim.DVPortgroupConfigSpec
$spec.configversion = $pg.Config.ConfigVersion
$spec.defaultPortConfig = New-Object VMware.Vim.VMwareDVSPortSetting
$spec.defaultPortConfig.ipfixEnabled = New-Object VMware.Vim.BoolPolicy
$spec.defaultPortConfig.ipfixEnabled.inherited = $false
$spec.defaultPortConfig.ipfixEnabled.value = $false
$pg.ReconfigureDVPortgroup_Task($spec)
}