| V-256428 | High | The ESXi host must have all security patches and updates installed. | Installing software updates is a fundamental mitigation against the exploitation of publicly known vulnerabilities. |
| V-256421 | High | All port groups on standard switches must be configured to reject guest Media Access Control (MAC) address changes. | If the virtual machine (VM) operating system changes the MAC address, it can send frames with an impersonated source MAC address at any time. This allows it to stage malicious attacks on the... |
| V-256410 | High | The ESXi Image Profile and vSphere Installation Bundle (VIB) acceptance levels must be verified. | Verify the ESXi Image Profile to only allow signed VIBs. An unsigned VIB represents untested code installed on an ESXi host. The ESXi Image profile supports four acceptance levels:
1.... |
| V-256429 | High | The ESXi host must exclusively enable Transport Layer Security (TLS) 1.2 for all endpoints. | TLS 1.0 and 1.1 are deprecated protocols with well-published shortcomings and vulnerabilities. TLS 1.2 should be enabled on all interfaces and SSLv3, TL 1.1, and 1.0 disabled, where... |
| V-256381 | Medium | The ESXi host must display the Standard Mandatory DOD Notice and Consent Banner before granting access to the system via the Direct Console User Interface (DCUI). | Failure to display the DOD logon banner prior to a logon attempt will negate legal proceedings resulting from unauthorized access to system resources.
Satisfies: SRG-OS-000023-VMM-000060,... |
| V-256380 | Medium | The ESXi host must enforce an unlock timeout of 15 minutes after a user account is locked out. | By enforcing a reasonable unlock timeout after multiple failed logon attempts, the risk of unauthorized access via user password guessing, otherwise known as brute forcing, is reduced. Users must... |
| V-256383 | Medium | The ESXi host SSH daemon must be configured with the DOD logon banner. | The warning message reinforces policy awareness during the logon process and facilitates possible legal action against attackers. Alternatively, systems whose ownership should not be obvious... |
| V-256382 | Medium | The ESXi host must display the Standard Mandatory DOD Notice and Consent Banner before granting access to the system via Secure Shell (SSH). | Failure to display the DOD logon banner prior to a logon attempt will negate legal proceedings resulting from unauthorized access to system resources. |
| V-256385 | Medium | The ESXi host Secure Shell (SSH) daemon must ignore ".rhosts" files. | SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts. SSH can emulate the behavior of the obsolete "rsh" command in allowing users to enable... |
| V-256384 | Medium | The ESXi host Secure Shell (SSH) daemon must use FIPS 140-2 validated cryptographic modules to protect the confidentiality of remote access sessions. | OpenSSH on the ESXi host ships with a FIPS 140-2 validated cryptographic module that is enabled by default. For backward compatibility reasons, this can be disabled so this setting can be audited... |
| V-256386 | Medium | The ESXi host Secure Shell (SSH) daemon must not allow host-based authentication. | SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts. SSH's cryptographic host-based authentication is more secure than ".rhosts"... |
| V-256389 | Medium | The ESXi host Secure Shell (SSH) daemon must perform strict mode checking of home directory configuration files. | If other users have access to modify user-specific SSH configuration files, they may be able to log on the system as another user. |
| V-256388 | Medium | The ESXi host Secure Shell (SSH) daemon must not permit user environment settings. | SSH environment options potentially allow users to bypass access restriction in some configurations. Users must not be able to present environment options to the SSH daemon. |
| V-256442 | Medium | The ESXi host rhttpproxy daemon must use FIPS 140-2 validated cryptographic modules to protect the confidentiality of remote access sessions. | ESXi runs a reverse proxy service called rhttpproxy that front ends internal services and application programming interfaces (APIs) over one HTTPS port by redirecting virtual paths to localhost... |
| V-256443 | Medium | The ESXi host must be configured with an appropriate maximum password age. | The older an ESXi local account password is, the larger the opportunity window is for attackers to guess, crack or reuse a previously cracked password. Rotating passwords on a regular basis is a... |
| V-256440 | Medium | The ESXi host must configure a session timeout for the vSphere API. | The vSphere API (VIM) allows for remote, programmatic administration of the ESXi host. Authenticated API sessions are no different from a risk perspective than authenticated UI sessions and they... |
| V-256441 | Medium | The ESXi Host Client must be configured with a session timeout. | The ESXi Host Client is the UI served up by the host itself, outside of vCenter. It is accessed by browsing to "https://<ESX FQDN>/ui". ESXi is not usually administered via this interface for long... |
| V-256446 | Medium | The ESXi host must require TPM-based configuration encryption. | An ESXi host's configuration consists of configuration files for each service that runs on the host. The configuration files typically reside in the /etc/ directory, but they can also reside in... |
| V-256447 | Medium | The ESXi host must implement Secure Boot enforcement. | Secure Boot is part of the UEFI firmware standard. With UEFI Secure Boot enabled, a host refuses to load any UEFI driver or app unless the operating system bootloader has a valid digital... |
| V-256444 | Medium | The ESXi host must not be configured to override virtual machine (VM) configurations. | Each VM on an ESXi host runs in its own "vmx" process. Upon creation, a vmx process will look in two locations for configuration items, the ESXi host itself and the per-vm *.vmx file in the VM... |
| V-256445 | Medium | The ESXi host must not be configured to override virtual machine (VM) logger settings. | Each VM on an ESXi host runs in its own "vmx" process. Upon creation, a vmx process will look in two locations for configuration items, the ESXi host itself and the per-vm *.vmx file in the VM... |
| V-256448 | Medium | The ESXi Common Information Model (CIM) service must be disabled. | The CIM system provides an interface that enables hardware-level management from remote applications via a set of standard application programming interfaces (APIs). These APIs are consumed by... |
| V-256449 | Medium | The ESXi host SSH daemon must be configured to only use FIPS 140-2 validated ciphers. | Use of weak or untested encryption algorithms undermines the purposes of using encryption to protect data. ESXi must implement cryptographic modules adhering to the higher standards approved by... |
| V-256406 | Medium | The ESXi host must terminate shell services after 10 minutes. | When the ESXi Shell or Secure Shell (SSH) services are enabled on a host, they will run indefinitely. To avoid having these services left running, set the "ESXiShellTimeOut". The... |
| V-256407 | Medium | The ESXi host must log out of the console UI after two minutes. | When the Direct Console User Interface (DCUI) is enabled and logged in, it should be automatically logged out if left logged on to avoid access by unauthorized persons. The "DcuiTimeOut" setting... |
| V-256404 | Medium | Active Directory ESX Admin group membership must not be used when adding ESXi hosts to Active Directory. | When adding ESXi hosts to Active Directory, all user/group accounts assigned to the Active Directory group \"ESX Admins\" will have full administrative access to the host.
If this group is not... |
| V-256405 | Medium | The ESXi host must set a timeout to automatically disable idle shell sessions after two minutes. | If a user forgets to log out of their local or remote ESXi Shell session, the idle connection will remain open indefinitely and increase the likelihood of inappropriate host access via session... |
| V-256424 | Medium | All port groups on standard switches must be configured to a value other than that of the native virtual local area network (VLAN). | ESXi does not use the concept of native VLAN. Frames with a VLAN specified in the port group will have a tag, but frames with VLAN not specified in the port group are not tagged and therefore will... |
| V-256379 | Medium | The ESXi host must enforce the limit of three consecutive invalid logon attempts by a user. | By limiting the number of failed logon attempts, the risk of unauthorized access via user password guessing, otherwise known as brute forcing, is reduced. Once the configured number of attempts is... |
| V-256400 | Medium | The ESXi host must be configured to disable nonessential capabilities by disabling Secure Shell (SSH). | The ESXi Shell is an interactive command line interface (CLI) available at the ESXi server console. The ESXi shell provides temporary access to commands essential for server maintenance. Intended... |
| V-256401 | Medium | The ESXi host must disable ESXi Shell unless needed for diagnostics or troubleshooting. | The ESXi Shell is an interactive command line environment available locally from the Direct Console User Interface (DCUI) or remotely via SSH. Activities performed from the ESXi Shell bypass... |
| V-256375 | Medium | Access to the ESXi host must be limited by enabling lockdown mode. | Enabling lockdown mode disables direct access to an ESXi host, requiring the host to be managed remotely from vCenter Server. This is done to ensure the roles and access controls implemented in... |
| V-256376 | Medium | The ESXi host must verify the DCUI.Access list. | Lockdown mode disables direct host access, requiring that administrators manage hosts from vCenter Server. However, if a host becomes isolated from vCenter, the administrator is locked out and can... |
| V-256377 | Medium | The ESXi host must verify the exception users list for lockdown mode. | While a host is in lockdown mode (strict or normal), only users on the "Exception Users" list are allowed access. These users do not lose their permissions when the host enters lockdown mode.... |
| V-256408 | Medium | The ESXi host must enable a persistent log location for all locally stored logs. | ESXi can be configured to store log files on an in-memory file system. This occurs when the host's "/scratch" directory is linked to "/tmp/scratch". When this is done, only a single day's worth of... |
| V-256409 | Medium | The ESXi host must configure NTP time synchronization. | To ensure the accuracy of the system clock, it must be synchronized with an authoritative time source within DOD. Many system functions, including time-based logon and activity restrictions,... |
| V-256420 | Medium | All port groups on standard switches must be configured to reject forged transmits. | If the virtual machine (VM) operating system changes the Media Access Control (MAC) address, the operating system can send frames with an impersonated source MAC address at any time. This allows... |
| V-256398 | Medium | The ESXi host must prohibit the reuse of passwords within five iterations. | If a user or root used the same password continuously or was allowed to change it back shortly after being forced to change it to something else, it would provide a potential intruder with the... |
| V-256396 | Medium | The ESXi host must produce audit records containing information to establish what type of events occurred. | Without establishing what types of events occurred, it would be difficult to establish, correlate, and investigate the events leading up to an outage or attack.
Satisfies:... |
| V-256397 | Medium | The ESXi host must be configured with a sufficiently complex password policy. | To enforce the use of complex passwords, minimum numbers of characters of different classes are mandated.
The use of complex passwords reduces the ability of attackers to successfully obtain... |
| V-256392 | Medium | The ESXi host Secure Shell (SSH) daemon must be configured to not allow X11 forwarding. | X11 forwarding over SSH allows for the secure remote execution of X11-based applications. This feature can increase the attack surface of an SSH connection. |
| V-256393 | Medium | The ESXi host Secure Shell (SSH) daemon must not permit tunnels. | OpenSSH has the ability to create network tunnels (layer 2 and layer 3) over an SSH connection. This function can provide similar convenience to a virtual private network (VPN) with the similar... |
| V-256390 | Medium | The ESXi host Secure Shell (SSH) daemon must not allow compression or must only allow compression after successful authentication. | If compression is allowed in an SSH connection prior to authentication, vulnerabilities in the compression software could result in compromise of the system from an unauthenticated connection,... |
| V-256419 | Medium | The ESXi host must enable Bridge Protocol Data Units (BPDU) filter on the host to prevent being locked out of physical switch ports with Portfast and BPDU Guard enabled. | BPDU Guard and Portfast are commonly enabled on the physical switch to which the ESXi host is directly connected to reduce the Spanning Tree Protocol (STP) convergence delay.
If a BPDU packet is... |
| V-256418 | Medium | The ESXi host must configure the firewall to block network traffic by default. | In addition to service-specific firewall rules, ESXi has a default firewall rule policy to allow or deny incoming and outgoing traffic. Reduce the risk of attack by ensuring this is set to deny... |
| V-256399 | Medium | The ESXi host must disable the Managed Object Browser (MOB). | The MOB provides a way to explore the object model used by the VMkernel to manage the host and enables configurations to be changed. This interface is meant to be used primarily for debugging the... |
| V-256423 | Medium | Use of the dvFilter network application programming interfaces (APIs) must be restricted. | If the organization is not using products that use the dvfilter network API, the host should not be configured to send network information to a virtual machine (VM).
If the API is enabled, an... |
| V-256403 | Medium | ESXi hosts using Host Profiles and/or Auto Deploy must use the vSphere Authentication Proxy to protect passwords when adding themselves to Active Directory. | If a host is configured to join an Active Directory domain using Host Profiles and/or Auto Deploy, the Active Directory credentials are saved in the profile and are transmitted over the network.... |
| V-256422 | Medium | All port groups on standard switches must be configured to reject guest promiscuous mode requests. | When promiscuous mode is enabled for a virtual switch, all virtual machines (VMs) connected to the Portgroup have the potential to read all packets across that network (only the virtual machines... |
| V-256411 | Medium | The ESXi host must protect the confidentiality and integrity of transmitted information by isolating vMotion traffic. | While encrypted vMotion is available, vMotion traffic should still be sequestered from other traffic to further protect it from attack. This network must only be accessible to other ESXi hosts,... |
| V-256413 | Medium | The ESXi host must protect the confidentiality and integrity of transmitted information by isolating IP-based storage traffic. | Virtual machines (VMs) might share virtual switches and VLANs with the IP-based storage configurations. IP-based storage includes vSAN, iSCSI, and NFS. This configuration might expose IP-based... |
| V-256412 | Medium | The ESXi host must protect the confidentiality and integrity of transmitted information by protecting ESXi management traffic. | The vSphere management network provides access to the vSphere management interface on each component. Services running on the management interface provide an opportunity for an attacker to gain... |
| V-256415 | Medium | The ESXi host must enable bidirectional Challenge-Handshake Authentication Protocol (CHAP) authentication for Internet Small Computer Systems Interface (iSCSI) traffic. | When enabled, vSphere performs bidirectional authentication of both the iSCSI target and host. When not authenticating both the iSCSI target and host, there is potential for a man-in-the-middle... |
| V-256414 | Medium | Simple Network Management Protocol (SNMP) must be configured properly on the ESXi host. | If SNMP is not being used, it must remain disabled. If it is being used, the proper trap destination must be configured. If SNMP is not properly configured, monitoring information can be sent to a... |
| V-256417 | Medium | The ESXi host must configure the firewall to restrict access to services running on the host. | Unrestricted access to services running on an ESXi host can expose a host to outside attacks and unauthorized access. Reduce the risk by configuring the ESXi firewall to only allow access from... |
| V-256425 | Medium | All port groups on standard switches must not be configured to virtual local area network (VLAN) 4095 unless Virtual Guest Tagging (VGT) is required. | When a port group is set to VLAN 4095, the vSwitch passes all network frames to the attached virtual machines (VMs) without modifying the VLAN tags. In vSphere, this is referred to as VGT. The VM... |
| V-256433 | Medium | The ESXi host must not suppress warnings about unmitigated hyperthreading vulnerabilities. | The L1 Terminal Fault (L1TF) CPU vulnerabilities published in 2018 have patches and mitigations available in vSphere. However, there are performance impacts to these mitigations that require... |
| V-256432 | Medium | The ESXi host must not suppress warnings that the local or remote shell sessions are enabled. | Warnings that local or remote shell sessions are enabled alert administrators to activity they may not be aware of and need to investigate. |
| V-256431 | Medium | The ESXi host must use DOD-approved certificates. | The default self-signed host certificate issued by the VMware Certificate Authority (VMCA) must be replaced with a DOD-approved certificate when the host will be accessed directly, such as during... |
| V-256430 | Medium | The ESXi host must enable Secure Boot. | Secure Boot is part of the Unified Extensible Firmware Interface (UEFI) firmware standard. With UEFI Secure Boot enabled, a host refuses to load any UEFI driver or app unless the operating system... |
| V-256437 | Medium | The ESXi host must enable strict x509 verification for SSL syslog endpoints. | 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... |
| V-256436 | Medium | The ESXi host must enable audit logging. | ESXi offers both local and remote audit recordkeeping to meet the requirements of the NIAP Virtualization Protection Profile and Server Virtualization Extended Package. Local records are stored on... |
| V-256435 | Medium | The ESXi host OpenSLP service must be disabled. | OpenSLP implements the Service Location Protocol to help CIM clients discover CIM servers over TCP 427. This service is not widely needed and has had vulnerabilities exposed in the past. To reduce... |
| V-256434 | Medium | The ESXi host Secure Shell (SSH) daemon must disable port forwarding. | While enabling Transmission Control Protocol (TCP) tunnels is a valuable function of sshd, this feature is not appropriate for use on the ESXi hypervisor. |
| V-256439 | Medium | The ESXi host must enable volatile key destruction. | By default, pages allocated for virtual machines (VMs), userspace applications, and kernel threads are zeroed out at allocation time. ESXi will always ensure that no nonzero pages are exposed to... |
| V-256438 | Medium | The ESXi host must verify certificates for SSL syslog endpoints. | When sending syslog data to a remote host, ESXi can be configured to use any combination of TCP, UDP and SSL transports. When using SSL, the server certificate must be validated to ensure that the... |
| V-256427 | Medium | The ESXi host must not provide root/administrator-level access to Common Information Model (CIM)-based hardware monitoring tools or other third-party applications. | The CIM system provides an interface that enables hardware-level management from remote applications via a set of standard application programming interfaces (APIs).
In environments that... |
| V-256378 | Medium | Remote logging for ESXi hosts must be configured. | Remote logging to a central log host provides a secure, centralized store for ESXi logs. By gathering host log files onto a central host, it can more easily monitor all hosts with a single tool.... |
| V-256426 | Medium | All port groups on standard switches must not be configured to virtual local area network (VLAN) values reserved by upstream physical switches. | Certain physical switches reserve certain VLAN IDs for internal purposes and often disallow traffic configured to these values. For example, Cisco Catalyst switches typically reserve VLANs 1001 to... |
| V-256387 | Low | The ESXi host Secure Shell (SSH) daemon must not allow authentication using an empty password. | Configuring this setting for the SSH daemon provides additional assurance that remote logon via SSH will require a password, even in the event of misconfiguration elsewhere. |
| V-256402 | Low | The ESXi host must use Active Directory for local user authentication. | Join ESXi hosts to an Active Directory domain to eliminate the need to create and maintain multiple local user accounts. Using Active Directory for user authentication simplifies the ESXi host... |
| V-256416 | Low | The ESXi host must disable Inter-Virtual Machine (VM) Transparent Page Sharing. | Published academic papers have demonstrated that by forcing a flush and reload of cache memory, it is possible to measure memory timings to try to determine an Advanced Encryption Standard (AES)... |
| V-256394 | Low | The ESXi host Secure Shell (SSH) daemon must set a timeout count on idle sessions. | Setting a timeout ensures that a user login will be terminated as soon as the "ClientAliveCountMax" is reached. |
| V-256395 | Low | The ESXi host Secure Shell (SSH) daemon must set a timeout interval on idle sessions. | Automatically logging out idle users guards against compromises via hijacked administrative sessions. |
| V-256391 | Low | The ESXi host Secure Shell (SSH) daemon must be configured to not allow gateway ports. | SSH Transmission Control Protocol (TCP) connection forwarding provides a mechanism to establish TCP connections proxied by the SSH server. This function can provide convenience similar to a... |
