Keys from SSH authorized_keys file must be removed.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-39347	SRG-OS-99999-ESXI5-000152	SV-51205r1_rule		Medium

Description
ESXi hosts come with SSH which can be enabled to allow remote access without requiring user authentication. To enable password free access copy the remote users public key into the "/etc/ssh/keys-root/authorized_keys" file on the ESXi host. The presence of the remote user's public key in the "authorized_keys" file identifies the user as trusted, meaning the user is granted access to the host without providing a password. Note: Lockdown mode does not apply to root users who log in using authorized keys. When you use an authorized key file for root user authentication, root users are not prevented from accessing a host with SSH even when the host is in lockdown mode.

Description

ESXi hosts come with SSH which can be enabled to allow remote access without requiring user authentication. To enable password free access copy the remote users public key into the "/etc/ssh/keys-root/authorized_keys" file on the ESXi host. The presence of the remote user's public key in the "authorized_keys" file identifies the user as trusted, meaning the user is granted access to the host without providing a password. Note: Lockdown mode does not apply to root users who log in using authorized keys. When you use an authorized key file for root user authentication, root users are not prevented from accessing a host with SSH even when the host is in lockdown mode.

STIG	Date
VMware ESXi Server 5.0 Security Technical Implementation Guide	2017-01-06

Details

Check Text ( C-46621r3_chk )
Temporarily disable Lockdown Mode and enable the ESXi Shell via the vSphere Client. Open the vSphere/VMware Infrastructure (VI) Client and log in with appropriate credentials. If connecting to vCenter Server, click on the desired host. Click the Configuration tab. Click Software, Security Profile, Services, Properties, ESXi Shell, and Options, respectively. Start the ESXi Shell service, where/as required. As root, log in to the host and verify the /etc/ssh/keys-root/authorized_keys file does not exist or is empty (zero bytes): # ls -l /etc/ssh/keys-root/authorized_keys If the authorized_keys file exists and is not empty, this is a finding. Re-enable Lockdown Mode on the host.

Check Text ( C-46621r3_chk )

Temporarily disable Lockdown Mode and enable the ESXi Shell via the vSphere Client.

Open the vSphere/VMware Infrastructure (VI) Client and log in with appropriate credentials.
If connecting to vCenter Server, click on the desired host.
Click the Configuration tab.
Click Software, Security Profile, Services, Properties, ESXi Shell, and Options, respectively.
Start the ESXi Shell service, where/as required.

As root, log in to the host and verify the /etc/ssh/keys-root/authorized_keys file does not exist or is empty (zero bytes):
# ls -l /etc/ssh/keys-root/authorized_keys

If the authorized_keys file exists and is not empty, this is a finding.

Re-enable Lockdown Mode on the host.

Fix Text (F-44361r3_fix)
Temporarily disable Lockdown Mode and enable the ESXi Shell via the vSphere Client. Open the vSphere/VMware Infrastructure (VI) Client and log in with appropriate credentials. If connecting to vCenter Server, click on the desired host. Click the Configuration tab. Click Software, Security Profile, Services, Properties, ESXi Shell and Options, respectively. Start the ESXi Shell service, where/as required. As root, log in to the host and zero/remove /etc/ssh/keys-root/authorized_keys file: # >/etc/ssh/keys-root/authorized_keys or # rm /etc/ssh/keys-root/authorized_keys Re-enable Lockdown Mode on the host.

Fix Text (F-44361r3_fix)

Temporarily disable Lockdown Mode and enable the ESXi Shell via the vSphere Client.

Open the vSphere/VMware Infrastructure (VI) Client and log in with appropriate credentials.
If connecting to vCenter Server, click on the desired host.
Click the Configuration tab.
Click Software, Security Profile, Services, Properties, ESXi Shell and Options, respectively.
Start the ESXi Shell service, where/as required.

As root, log in to the host and zero/remove /etc/ssh/keys-root/authorized_keys file:
# >/etc/ssh/keys-root/authorized_keys
or
# rm /etc/ssh/keys-root/authorized_keys

Re-enable Lockdown Mode on the host.