HP FlexFabric Switch L2S Security Technical Implementation Guide

V1R2 2018-12-21       U_HP_FlexFabric_Switch_L2S_STIG_V1R2_Manual-xccdf.xml
V1R1 2016-02-29       U_HP_FlexFabric_Switch_L2S_STIG_V1R1_Manual-xccdf.xml
This Security Technical Implementation Guide is published as a tool to improve the security of Department of Defense (DoD) information systems. The requirements are derived from the National Institute of Standards and Technology (NIST) 800-53 and related documents. Comments or proposed revisions to this document should be sent via e-mail to the following address: [email protected]
Comparison
All 25
No Change 24
Updated 0
Added 0
Removed 1
V-65961 No Change
Findings ID: HFFS-L2-000001 Rule ID: SV-80451r1_rule Severity: medium CCI: CCI-000381

Discussion

A compromised switch introduces risk to the entire network infrastructure as well as data resources that are accessible via the network. The perimeter defense has no oversight or control of attacks by malicious users within the network. Preventing network breaches from within is dependent on implementing a comprehensive defense-in-depth strategy, including securing each device connected to the network. This is accomplished by following and implementing all security guidance applicable for each node type. A fundamental step in securing each switch is to enable only the capabilities required for operation.

Checks

Review the HP FlexFabric Switch configuration to determine if services or functions not required for operation, or not related to switch functionality, are enabled.

If unnecessary services and functions are enabled on the HP FlexFabric Switch, this is a finding.

[HP] display ftp-server
FTP is not configured.

[HP] display current-configuration | include telnet

Note: When Telnet server is enabled, the output for this command is telnet server enable.

Fix

Remove unneeded services and functions from the HP FlexFabric Switch. Removal is recommended since the service or function may be inadvertently enabled otherwise. However, if removal is not possible, disable the service or function.

Disable unsecure protocols and services on the HP FlexFabric Switch:

[HP] undo ftp server enable
[HP] undo telnet server enable

Note: By default, both FTP and Telnet services are disabled.
V-66051 No Change
Findings ID: HFFS-L2-000002 Rule ID: SV-80541r1_rule Severity: high CCI: CCI-001958

Discussion

Controlling LAN access via 802.1x authentication or MAC authentication can assist in preventing a malicious user from connecting an unauthorized PC to a switch port to inject or receive data from the network without detection.

Checks

Verify all access switch ports connecting to LAN outlets are configured for 802.1x or MAC authentication as shown in these configuration examples.

802.1x example:

interface Ten-GigabitEthernet1/0/4
port link-mode bridge
port access vlan 200
dot1x

MAC authentication example:

interface Ten-GigabitEthernet1/0/5
port link-mode bridge
port access vlan 200
mac-authentication

If all access switch ports connecting to LAN outlets are not configured for 802.1x or MAC authentication, this is a finding.

Fix

Configure 802.1 x authentications on all host-facing access switch ports. To authenticate those devices that do not support 802.1x, MAC Authentication Bypass must be configured.

[HP] dot1x
[HP] dot1x authentication-method eap
[HP] domain radius jitc
[HP] radius scheme jitc
[HP-radius-jitc]radius scheme jitc
[HP-radius-jitc]primary authentication 15.252.76.124
[HP-radius-jitc]primary accounting 15.252.76.124
[HP-radius-jitc]accounting-on enable
[HP-radius-jitc]key authentication simple test123
[HP-radius-jitc]user-name-format without-domain
[HP-radius-jitc]nas-ip 15.252.78.99
[HP]domain jitc
[HP-isp-jitc]domain jitc
[HP-isp-jitc]authentication lan-access radius-scheme jitc
[HP-isp-jitc]authorization lan-access radius-scheme jitc
[HP] interface gigbitethernet 1/0/1
[HP-Gigabitethernet1/0/1] undo dot1x handshake
dot1x mandatory-domain jitc
undo dot1x multicast-trigger
V-66053 No Change
Findings ID: HFFS-L2-000003 Rule ID: SV-80543r1_rule Severity: medium CCI: CCI-001967

Discussion

Controlling LAN access via 802.1x authentication can assist in preventing a malicious user from connecting an unauthorized PC to a switch port to inject or receive data from the network without detection.

Checks

Verify all access switch ports connecting to LAN outlets are configured for 802.1x or MAC authentication as shown in this configuration example.

802.1x example:

interface Ten-GigabitEthernet1/0/4
port link-mode bridge
port access vlan 200
dot1x

If all access switch ports connecting to LAN outlets are not configured for 802.1x, this is a finding.

Fix

Configure 802.1 x authentications on all host-facing access switch ports. To authenticate those devices that do not support 802.1x, MAC Authentication Bypass must be configured.

[HP] dot1x
[HP] dot1x authentication-method eap
[HP] domain radius jitc
[HP] radius scheme jitc
[HP-radius-jitc]radius scheme jitc
[HP-radius-jitc]primary authentication 15.252.76.124
[HP-radius-jitc]primary accounting 15.252.76.124
[HP-radius-jitc]accounting-on enable
[HP-radius-jitc]key authentication simple test123
[HP-radius-jitc]user-name-format without-domain
[HP-radius-jitc]nas-ip 15.252.78.99
[HP]domain jitc
[HP-isp-jitc]domain jitc
[HP-isp-jitc]authentication lan-access radius-scheme jitc
[HP-isp-jitc]authorization lan-access radius-scheme jitc
[HP] interface gigbitethernet 1/0/1
[HP-Gigabitethernet1/0/1] undo dot1x handshake
[HP-Ten-GigabitEthernet1/0/7]dot1x mandatory-domain jitc
[HP-Ten-GigabitEthernet1/0/7]undo dot1x multicast-trigger
[HP-Ten-GigabitEthernet1/0/7]dot1x re-authenticate
V-66057 No Change
Findings ID: HFFS-L2-000006 Rule ID: SV-80547r1_rule Severity: medium CCI: CCI-001095

Discussion

Denial of service is a condition when a resource is not available for legitimate users. Packet flooding DDoS attacks are referred to as volumetric attacks and have the objective of overloading a network or circuit to deny or seriously degrade performance, which denies access to the services that normally traverse the network or circuit. Volumetric attacks have become relatively easy to launch by using readily available tools such as Low Orbit Ion Cannon or by using botnets.

Measures to mitigate the effects of a successful volumetric attack must be taken to ensure that sufficient capacity is available for mission-critical traffic. Managing capacity may include, for example, establishing selected network usage priorities or quotas and enforcing them using rate limiting, Quality of Service (QoS), or other resource reservation control methods. These measures may also mitigate the effects of sudden decreases in network capacity that are the result of accidental or intentional physical damage to telecommunications facilities (such as cable cuts or weather-related outages).

Checks

Check if the HP FlexFabric Switch is configured to protect against known DoS attacks by implementing a control plane QoS policy to rate limit specify traffic types destined to the switch.

[HP] display qos policy control-plane pre-defined

[HP] display qos policy user-defined

If the HP FlexFabric Switch is not configured with a control plane QoS policy, this is a finding.

Fix

Configure QoS policy and apply it to the control plane:
[HP] traffic classifier Net-Protocols operator and
[HP-classifier Net-Protocols] if-match control-plane protocol icmp
[HP-classifier Net-Protocols] quit
[HP] traffic behavior Net-Protocols
[HP-behavior-Net-Protocols] car cir 320
[HP-behavior-Net-Protocols] quit
[HP] qos policy Net-protocols
[HP-qospolicy-Net-Protocols] classifier Net-Protocols behavior Net-protocols
[HP-qospolicy-Net-Protocols] quit
[HP] control-plane slot 1
[HP-cp-slot1] qos apply policy Net-Protocols inbound

Note: In addition, ACLs can be deployed to address specific types of attacks based on IP, MAC, protocols and ports.
Note: By default, the HP FlexFabric Switches are configured with pre-defined control plane QoS policies, which take effect on the control planes by default.
V-66059 No Change
Findings ID: HFFS-L2-000008 Rule ID: SV-80549r1_rule Severity: medium CCI: CCI-001919

Discussion

Without the capability to select a user session to capture/record or view/hear, investigations into suspicious or harmful events would be hampered by the volume of information captured. The volume of information captured may also adversely impact the operation for the network. Session audits may include port mirroring, tracking websites visited, and recording information and/or file transfers.

Checks

Verify that the HP FlexFabric Switch is capable of capturing ingress and egress packets from any designated switch port for the purpose of monitoring a specific user session.

If the HP FlexFabric Switch is not capable of capturing ingress and egress packets from a designated switch port, this is a finding.

[HP]display mirroring-group X
Mirroring group X:

Type: Remote source
Status: Active
Mirroring port: GigabitEthernet1/0/1 Both
Monitor port: GigabitEthernet1/0/2

Fix

Configure the HP FlexFabric Switch to capture ingress and egress packets from any designated switch port for the purpose of monitoring a specific user session as shown in the following example:

[HP]mirroring-group 1 local

[HP]mirroring-group 1 mirroring-port GigabitEthernet 1/0/1 both

[HP]mirroring-group 1 monitor-port GigabitEthernet 1/0/2
V-66061 No Change
Findings ID: HFFS-L2-000009 Rule ID: SV-80551r1_rule Severity: medium CCI: CCI-001920

Discussion

Without the capability to remotely view/hear all content related to a user session, investigations into suspicious user activity would be hampered. Real-time monitoring allows authorized personnel to take action before additional damage is done. The ability to observe user sessions as they are happening allows for interceding in ongoing events that after-the-fact review of captured content would not allow.

Checks

Verify that the HP FlexFabric Switch is capable of capturing ingress and egress packets from any designated switch port for the purpose of remotely monitoring a specific user session.

If the HP FlexFabric Switch is not capable of capturing ingress and egress packets from a designated switch port for the purpose of remotely monitoring a specific user session, this is a finding.

Fix

Configure the HP FlexFabric Switch to remotely capture ingress and egress packets from any designated switch port for the purpose of monitoring a specific user session as shown in the following example:

[HP]mirroring-group 1 remote-source

[HP]mirroring-group 1 mirroring-port GigabitEthernet 1/0/1 both

[HP]mirroring-group 1 monitor-port GigabitEthernet 1/0/2
V-66063 No Change
Findings ID: HFFS-L2-000010 Rule ID: SV-80553r1_rule Severity: medium CCI: CCI-002385

Discussion

Spanning Tree Protocol (STP) does not provide any means for the network administrator to securely enforce the topology of the switched network. Any switch can be the root bridge in a network. However, a more optimal forwarding topology places the root bridge at a specific predetermined location. With the standard STP, any bridge in the network with a lower bridge ID takes the role of the root bridge. The administrator cannot enforce the position of the root bridge but can set the root bridge priority to 0 in an effort to secure the root bridge position.

The root guard feature provides a way to enforce the root bridge placement in the network. If the bridge receives superior STP Bridge Protocol Data Units (BPDUs) on a root guard-enabled port, root guard moves this port to a root-inconsistent STP state and no traffic can be forwarded across this port while it is in this state. To enforce the position of the root bridge it is imperative that root guard is enabled on all ports where the root bridge should never appear.

Checks

Review the HP FlexFabric Switch topology as well as the configuration to verify that root guard is enabled on switch ports facing users or switches that are downstream from the root bridge.

If the switch has not enabled Root Guard on all ports where the root bridge should not appear, this is a finding.

[HP]display stp
-------[CIST Global Info][Mode MSTP]-------
Bridge ID : 0.bcea-fa14-f0a4
Bridge times : Hello 2s MaxAge 20s FwdDelay 15s MaxHops 20
Root ID/ERPC : 0.bcea-fa14-f0a4, 0
RegRoot ID/IRPC : 0.bcea-fa14-f0a4, 0
RootPort ID : 0.0
BPDU-Protection : Disabled
Bridge Config-
Digest-Snooping : Disabled
TC or TCN received : 19824
Time since last TC : 0 days 1h:3m:4s

----[Port1(GigabitEthernet1/0/1)][DISCARDING]----
Port protocol : Enabled
Port role : Designated Port (Boundary)
Port ID : 128.1
Port cost(Legacy) : Config=auto, Active=20
Desg.bridge/port : 0.bcea-fa14-f0a4, 128.1
Port edged : Config=disabled, Active=disabled
Point-to-Point : Config=auto, Active=true
Transmit limit : 10 packets/hello-time
TC-Restriction : Disabled
Role-Restriction : Disabled
Protection type : ROOT

Fix

Configure the HP FlexFabric Switch to have Root Guard enabled on all ports where the root bridge should not appear.

[HP-GigabitEthernet1/0/1]stp root-protection
V-66065 No Change
Findings ID: HFFS-L2-000011 Rule ID: SV-80555r1_rule Severity: medium CCI: CCI-002385

Discussion

If a rogue switch is introduced into the topology and transmits a Bridge Protocol Data Unit (BPDU) with a lower bridge priority than the existing root bridge, it will become the new root bridge and cause a topology change, rendering the network in a suboptimal state. The Spanning Tree Protocol (STP) PortFast BPDU guard enhancement allows network designers to enforce the STP domain borders and keep the active topology predictable. The devices behind the ports that have STP PortFast enabled are not able to influence the STP topology. At the reception of BPDUs, the BPDU guard operation disables the port that has PortFast configured. The BPDU guard transitions the port into errdisable state and sends a log message.

Checks

Review the HP FlexFabric Switch configuration to verify that BPDU Protection is enabled on all user-facing switch ports.

If the HP FlexFabric Switch has not enabled BPDU protection, this is a finding.

[HP] display stp
-------[CIST Global Info][Mode MSTP]-------
Bridge ID : 32768.7848-596a-6580
Bridge times : Hello 2s MaxAge 20s FwdDelay 15s MaxHops 20
Root ID/ERPC : 32768.7848-596a-6580, 0
RegRoot ID/IRPC : 32768.7848-596a-6580, 0
RootPort ID : 0.0
BPDU-Protection : Enabled
Bridge Config-
Digest-Snooping : Disabled
TC or TCN received : 0
Time since last TC : 3 days

interface GigabitEthernet1/0/1
stp edged-port

Fix

Configure the HP FlexFabric Switch to have BPDU Guard enabled on all user-facing switch ports.

[HP]stp bpdu-protection
[HP-GigabitEthernet1/0/1]stp edged-port
V-66067 No Change
Findings ID: HFFS-L2-000012 Rule ID: SV-80557r1_rule Severity: medium CCI: CCI-002385

Discussion

The Spanning Tree Protocol (STP) loop Protection feature provides additional protection against STP loops. An STP loop is created when an STP blocking port in a redundant topology erroneously transitions to the forwarding state. In its operation, STP relies on continuous reception and transmission of BPDUs based on the port role. The designated port transmits BPDUs, and the non-designated port receives BPDUs. When one of the ports in a physically redundant topology no longer receives BPDUs, the STP conceives that the topology is loop free. Eventually, the blocking port from the alternate or backup port becomes a designated port and moves to a forwarding state. This situation creates a loop. The loop Protection feature makes additional checks. If BPDUs are not received on a non-designated port and loop guard is enabled, that port is moved into the STP loop-inconsistent blocking state.

Checks

Review the HP FlexFabric Switch configuration to verify that STP Loop Protection is enabled.

If STP Loop Protection is not configured globally or at a minimum on non-designated STP ports, this is a finding.

[HPinterface Ten-GigabitEthernet1/0/8]
port link-mode bridge
stp loop-protection

Fix

Configure the HP FlexFabric Switch to have STP Loop Protection enabled globally or at a minimum on all non-designated switch ports.

[HPinterface Ten-GigabitEthernet1/0/8]
stp loop-protection
V-66069 No Change
Findings ID: HFFS-L2-000013 Rule ID: SV-80559r1_rule Severity: medium CCI: CCI-002385

Discussion

Access layer switches use the Content Addressable Memory (CAM) table to direct traffic to specific ports based on the VLAN number and the destination MAC address of the frame. When a router has an ARP entry for a destination host and forwards it to the access layer switch and there is no entry corresponding to the frame's destination MAC address in the incoming VLAN, the frame will be sent to all forwarding ports within the respective VLAN, which causes flooding. Large amounts of flooded traffic can saturate low-bandwidth links, causing network performance issues or complete connectivity outage to the connected devices. Unknown unicast flooding has been a nagging problem in networks that have asymmetric routing and default timers. To mitigate the risk of a connectivity outage, the storm-constrain feature must be implemented on all access layer switches. The storm-constrain feature will block unknown unicast traffic flooding and only permit egress traffic with MAC addresses that are known to exit on the port.

Checks

Review the HP FlexFabric Switch configuration to verify that unknown storm-constrain is enabled on all access switch ports.

If any access switch ports do not have storm-constrain enabled, this is a finding.

[HP] display storm-constrain
Abbreviation: BC - broadcast; MC - multicast; UC - unicast
FW - forwarding
Flow Statistic Interval: 10 (in seconds)
Port Type Lower Upper Unit CtrlMode Status Trap Log SwitchNum
--------------------------------------------------------------------------------
XGE1/0/10 UC 1 1 pps shutdown FW on on 0

Fix

Configure the HP FlexFabric Switch to have unknown storm-constrain enabled.

[HP-GigabitEthernet1/0/1]storm-constrain unicast pps 1 1

[HP-GigabitEthernet1/0/1]storm-constrain control shutdown
V-66071 No Change
Findings ID: HFFS-L2-000014 Rule ID: SV-80561r1_rule Severity: medium CCI: CCI-002385

Discussion

In an enterprise network, devices under administrative control are trusted sources. These devices include the switches, routers, and servers in the network. Host ports and unknown Dynamic Host Configuration Protocol (DHCP) servers are considered untrusted sources. An unknown DHCP server on the network on an untrusted port is called a spurious DHCP server--
any device (PC, Wireless Access Point) that is loaded with DHCP server enabled. The DHCP snooping feature determines whether traffic sources are trusted or untrusted. The potential exists for a spurious DHCP server to respond to DHCPDISCOVER messages before the real server has time to respond. DHCP snooping allows switches on the network to trust the port a DHCP server is connected to and not trust the other ports.

The DHCP snooping feature validates DHCP messages received from untrusted sources and filters out invalid messages as well as rate-limits DHCP traffic from trusted and untrusted sources. DHCP snooping feature builds and maintains a binding database, which contains information about untrusted hosts with leased IP addresses, and it utilizes the database to validate subsequent requests from untrusted hosts. Other security features, such as IP Source Guard and Dynamic ARP Inspection (DAI), also use information stored in the DHCP snooping binding database. Hence, it is imperative that the DHCP snooping feature is enabled on all VLANs.

Checks

Review the HP FlexFabric Switch configuration and verify that DHCP snooping is enabled on a per-VLAN basis.

If the HP FlexFabric Switch does not have DHCP snooping enabled for all user VLANs to validate DHCP messages from untrusted sources as well as rate-limit DHCP traffic, this is a finding.

Note: Enabling DHCP snooping on a range of VLANs is permissible.

Sample output:
[HP]dhcp snooping enable

[HP-GigabitEthernet1/0/1]dhcp snooping rate-limit

Fix

Configure the HP FlexFabric Switch to have DHCP snooping for all user VLANs to validate DHCP messages from untrusted sources as well as rate-limit DHCP traffic.

[HP]dhcp snooping enable

[HP-GigabitEthernet1/0/1]dhcp snooping rate-limit
V-66073 No Change
Findings ID: HFFS-L2-000015 Rule ID: SV-80563r1_rule Severity: medium CCI: CCI-002385

Discussion

IP Source Guard provides source IP address filtering on a Layer 2 port to prevent a malicious host from impersonating a legitimate host by assuming the legitimate host's IP address. The feature uses dynamic DHCP snooping and static IP source binding to match IP addresses to hosts on untrusted Layer 2 access ports. Initially, all IP traffic on the protected port is blocked except for DHCP packets. After a client receives an IP address from the DHCP server, or after static IP source binding is configured by the administrator, all traffic with that IP source address is permitted from that client. Traffic from other hosts is denied. This filtering limits a host's ability to attack the network by claiming a neighbor host's IP address.

Checks

Review the HP FlexFabric Switch configuration to verify that IP Source Guard is enabled on all untrusted access switch ports.

If the HP FlexFabric Switch does not have IP Source Guard enabled on all user-facing or untrusted access switch ports, this is a finding.

[HP]dis ip source binding static
Total entries found: 0
IP Address MAC Address Interface VLAN Type

Fix

Configure the HP FlexFabric Switch to have IP Source Guard enabled on all user-facing or untrusted access switch ports.

[HP-Ten-GigabitEthernet1/0/10]
[HP-Ten-GigabitEthernet1/0/10]ip verify source ip-address [ mac-address ]
[HP-Ten-GigabitEthernet1/0/10]ip source binding ip-address ip-address [ mac-address mac-address ] [ vlan vlan-id ]
V-66075 No Change
Findings ID: HFFS-L2-000016 Rule ID: SV-80565r1_rule Severity: medium CCI: CCI-002385

Discussion

DAI intercepts Address Resolution Protocol (ARP) requests and verifies that each of these packets has a valid IP-to-MAC address binding before updating the local ARP cache and before forwarding the packet to the appropriate destination. Invalid ARP packets are dropped and logged. DAI determines the validity of an ARP packet based on valid IP-to-MAC address bindings stored in the DHCP snooping binding database. If the ARP packet is received on a trusted interface, the switch forwards the packet without any checks. On untrusted interfaces, the switch forwards the packet only if it is valid.

Checks

Review the HP FlexFabric Switch configuration to verify that Dynamic ARP Inspection (DAI) feature is enabled on all user VLANs.

If DAI is not enabled on all user VLANs, this is a finding.

[HP]display arp detection
ARP detection is enabled in the following VLANs:
2

[HP]display arp detection statistics interface Ten-GigabitEthernet 1/0/11
State: U-Untrusted T-Trusted
ARP packets dropped by ARP inspect checking:
Interface(State) IP Src-MAC Dst-MAC Inspect
XGE1/0/11(T) 0 0 0 0
[HP]

Fix

Configure the HP FlexFabric Switch to have Dynamic ARP Inspection (DAI) enabled on all user VLANs.

[HP-vlan2]arp detection enable

[HP-Ten-GigabitEthernet1/0/11]arp detection trust
V-66077 No Change
Findings ID: HFFS-L2-000020 Rule ID: SV-80567r1_rule Severity: medium CCI: CCI-000366

Discussion

Spanning Tree Protocol (STP) is implemented on bridges and switches to prevent layer 2 loops when a broadcast domain spans multiple bridges and switches and when redundant links are provisioned to provide high availability in case of link failures. Convergence time can be significantly reduced using Rapid STP (802.1w) instead of STP (802.1d), resulting in improved availability. Rapid STP should be deployed by implementing either Rapid or Multiple Spanning-Tree Protocol (MSTP) -- the latter scales much better when there are many VLANs.

Checks

In cases where VLANs do not span multiple switches, it is a best practice to not implement STP. Avoiding the use of STP will provide the most deterministic and highly available network topology. If STP is required, then review the HP FlexFabric Switch configuration to verify that Rapid STP has been implemented.

If Rapid STP has not been implemented where STP is required, this is a finding.

[HP]display stp vlan X

Fix

Configure Rapid STP to be implemented at the access and distribution layers where VLANs span multiple switches.
V-66079 No Change
Findings ID: HFFS-L2-000021 Rule ID: SV-80569r1_rule Severity: medium CCI: CCI-000366

Discussion

In topologies where fiber optic interconnections are used, physical misconnections can occur that allow a link to appear to be up when there is a mismatched set of transmit/receive pairs. When such a physical misconfiguration occurs, protocols such as STP can cause network instability. Device Link Detection Protocol (DLDP) is a layer 2 protocol that can detect these physical misconfigurations by verifying that traffic is flowing bidirectionally between neighbors. Ports with DLDP enabled periodically transmit packets to neighbor devices. If the packets are not echoed back within a specific time frame, the link is flagged as unidirectional and the interface is shut down.

Checks

If any of the switch ports have fiber optic interconnections with neighbors, review the HP FlexFabric Switch configuration to verify that DLDP is enabled globally or on a per interface basis.

If the HP FlexFabric Switch has fiber optic interconnections with neighbors and DLDP is not enabled, this is a finding.

<HP> display dldp
DLDP global status : disable
DLDP interval : 5s
DLDP work-mode : enhance
DLDP authentication-mode : none
DLDP unidirectional-shutdown : auto
DLDP delaydown-timer : 1s
The number of enabled ports is 2.
[HP-Interface Ethernet1/1]
DLDP port state : advertisement
DLDP link state : up
The neighbor number of the port is 0.
[HP-Interface Ethernet1/2]
DLDP port state : advertisement
DLDP link state : up
The neighbor number of the port is 0.

Fix

Configure the HP FlexFabric Switch to enable Device Link Detection Protocol (DLDP) to protect against one-way connections.

[HP]dldp global enable

[HP-Ten-GigabitEthernet1/0/47]dldp enable
V-66081 No Change
Findings ID: HFFS-L2-000022 Rule ID: SV-80571r1_rule Severity: medium CCI: CCI-000366

Discussion

When trunk negotiation is enabled via Dynamic Trunk Protocol (DTP), considerable time can be spent negotiating trunk settings (802.1q or ISL) when a node or interface is restored. While this negotiation is happening, traffic is dropped because the link is up from a layer 2 perspective. Packet loss can be eliminated by setting the interface statically to trunk mode, thereby avoiding dynamic trunk protocol negotiation and significantly reducing any outage when restoring a failed link or switch.

Checks

Review the HP FlexFabric Switch configuration to verify that trunk negotiation is disabled by statically configuring all trunk links. Configuring a command to manually disable negotiation may also be required for some switch platforms.

If trunk negotiation is enabled on any interface, this is a finding.

Sample output:
interface GigabitEthernet1/0/1
port link-type trunk
port trunk permit vlan X

Fix

Configure the HP FlexFabric Switch to enable trunk links statically.

[HP-GigabitEthernet1/0/1]port link-type trunk
V-66083 No Change
Findings ID: HFFS-L2-000023 Rule ID: SV-80573r1_rule Severity: medium CCI: CCI-000366

Discussion

Limiting the number of registered MAC addresses on a switch access port can help prevent a Content Addressable Memory (CAM) table overflow attack. This type of attack lets an attacker exploit the hardware and memory limitations of a switch. If there are enough entries stored in a CAM table before the expiration of other entries, no new entries can be accepted into the CAM table. An attacker will be able to flood the switch with mostly invalid MAC addresses until the CAM table’s resources have been depleted. When there are no more resources, the switch has no choice but to flood all ports within the VLAN with all incoming traffic. This happens because the switch cannot find the switch port number for a corresponding MAC address within the CAM table, allowing the switch to become a hub and traffic to be monitored.

Checks

Review the HP FlexFabric Switch configuration to verify each access port is configured for a single registered MAC address. Configuring port-security on the HP FlexFabric Switch access port interface will automatically set the maximum number of registered MAC addresses to one.

If any switch port has more than one MAC address assigned to it, this is a finding.

Exemptions: Some deployments are exempt from requiring a single MAC address per access switch port. VoIP or VTC endpoints may provide a PC port thereby enabling a PC to be connected using the same switch port. The MAC address of each device will need to be registered to the appropriate access switch port. Another exempt case scenario is “hot-desking”, where a single connection is shared among several devices and several people are assigned to work at the same desk at different times, each user with their own PC. In this case, a different MAC address needs to be permitted for each PC that is connecting to the LAN drop in the workspace.

Sample output:
[HPGigabitEthernet1/0/1]display this
#
interface GigabitEthernet1/0/1
port-security max-mac-count 1

Fix

Configure the HP FlexFabric Switch to limit the maximum number of registered MAC addresses on each access switch port to one.

[HP-GigabitEthernet1/0/1]port-security max-mac-count 1
V-66085 No Change
Findings ID: HFFS-L2-000024 Rule ID: SV-80575r1_rule Severity: medium CCI: CCI-000366

Discussion

It is possible that a disabled port that is assigned to a user or management VLAN becomes enabled by accident or by an attacker and as a result gains access to that VLAN as a member.

Checks

Review the HP FlexFabric Switch configurations and examine all access switch ports. Each access switch port not in use should have membership to an inactive VLAN that is not used for any purpose and is not allowed on any trunk links.

If there are any access switch ports not in use and not in an inactive VLAN, this is a finding.

<HP>display vlan X
VLAN ID: X
VLAN type: Static
Route interface: Configured:
Description: VLAN 000X
Name: VLAN 000X
Tagged ports: None
Untagged ports:
GigabitEthernet1/0/1 GigabitEthernet1/0/2
GigabitEthernet1/0/3 GigabitEthernet1/0/4

Fix

Assign all switch ports not in use to an inactive VLAN.

[HP-vlanX]port GigabitEthernet 1/0/1 to GigabitEthernet 1/0/48
V-66087 No Change
Findings ID: HFFS-L2-000025 Rule ID: SV-80577r1_rule Severity: medium CCI: CCI-000366

Discussion

In a VLAN-based network, switches use the default VLAN (i.e., VLAN 1) for in-band management and to communicate with other networking devices using Spanning-Tree Protocol (STP), Dynamic Trunking Protocol (DTP), VLAN Trunking Protocol (VTP), and Port Aggregation Protocol (PAgP)—all untagged traffic. As a consequence, the default VLAN may unwisely span the entire network if not appropriately pruned. If its scope is large enough, the risk of compromise can increase significantly.

Checks

Review the HP FlexFabric Switch configurations and verify that no access switch ports have been assigned membership to the default VLAN (i.e., VLAN 1). A good method of ensuring there is not membership to the default VLAN is to have it disabled (i.e., shutdown) on the switch.

If there are access switch ports assigned to the default VLAN, this is a finding.

<HP>display vlan 1
VLAN ID: 1
VLAN type: Static
Route interface: Configured:
Description: VLAN 0001
Name: VLAN 0001
Tagged ports: None
Untagged ports:
GigabitEthernet1/0/1 GigabitEthernet1/0/2
GigabitEthernet1/0/3 GigabitEthernet1/0/4

[HP-GigabitEthernet1/0/12]shutdown

Fix

Remove the assignment of the default VLAN from all access switch ports.

<HP>display vlan 1

[HP-vlan2]port GigabitEthernet 1/0/1 to GigabitEthernet 1/0/48

[HP-GigabitEthernet1/0/1]shutdown
V-66089 No Change
Findings ID: HFFS-L2-000026 Rule ID: SV-80579r1_rule Severity: medium CCI: CCI-000366

Discussion

The default VLAN (i.e., VLAN 1) is a special VLAN used for control plane traffic such as Spanning-Tree Protocol (STP), Dynamic Trunking Protocol (DTP), VLAN Trunking Protocol (VTP), and Port Aggregation Protocol (PAgP). VLAN 1 is enabled on all trunks and ports by default. With larger campus networks, care needs to be taken about the diameter of the STP domain for the default VLAN. Instability in one part of the network could affect the default VLAN, thereby influencing control-plane stability and therefore STP stability for all other VLANs.

Checks

Review the HP FlexFabric Switch configuration and verify that the default VLAN is pruned from trunk links that do not require it.

If the default VLAN is not pruned from trunk links that should not be transporting frames for the VLAN, this is a finding.

<HP>display vlan 1

VLAN ID: 1
VLAN type: Static
Route interface: Configured
Description: VLAN 0001
Name: VLAN 0001
Tagged ports: None
Untagged ports:
GigabitEthernet1/0/1 GigabitEthernet1/0/2
GigabitEthernet1/0/3 GigabitEthernet1/0/4
GigabitEthernet1/0/5 GigabitEthernet1/0/6
GigabitEthernet1/0/7 GigabitEthernet1/0/8

Fix

Remove the native vlan from trunks that do not require it.

[HP-interface GigabitEthernet1/0/1] undo port trunk permit vlan 1
V-66091 No Change
Findings ID: HFFS-L2-000027 Rule ID: SV-80581r1_rule Severity: medium CCI: CCI-000366

Discussion

Switches use the default VLAN (i.e., VLAN 1) for in-band management and to communicate with directly connected switches using Spanning-Tree Protocol (STP), Dynamic Trunking Protocol (DTP), VLAN Trunking Protocol (VTP), and Port Aggregation Protocol (PAgP)—all untagged traffic. As a consequence, the default VLAN may unwisely span the entire network if not appropriately pruned. If its scope is large enough, the risk of compromise can increase significantly.

Checks

Review the HP FlexFabric Switch configuration and verify that the default VLAN is not used to access the switch for management.

If the default VLAN is being used to access the HP FlexFabric Switch, this is a finding.

<HP>display vlan 1

VLAN ID: 1
VLAN type: Static
Route interface: Configured
Description: VLAN 0001
Name: VLAN 0001
Tagged ports: None
Untagged ports:
GigabitEthernet1/0/1 GigabitEthernet1/0/2
GigabitEthernet1/0/3 GigabitEthernet1/0/4
GigabitEthernet1/0/5 GigabitEthernet1/0/6
GigabitEthernet1/0/7 GigabitEthernet1/0/8

Fix

Configure the HP FlexFabric Switch for management access to use a VLAN other than the default VLAN.

interface Vlan-interface xxxx
description MGMT VLAN
ip address xxx.xxx.xxx.xxx <mask>
V-66093 No Change
Findings ID: HFFS-L2-000028 Rule ID: SV-80583r1_rule Severity: medium CCI: CCI-000366

Discussion

Double encapsulation can be initiated by an attacker who has access to a switch port belonging to the native VLAN of the trunk port. Knowing the victim's MAC address and with the victim attached to a different switch belonging to the same trunk group, thereby requiring the trunk link and frame tagging, the malicious user can begin the attack by sending frames with two sets of tags. The outer tag that will have the attacker's VLAN ID (probably the well-known and omnipresent default VLAN) is stripped off by the switch, and the inner tag that will have the victim's VLAN ID is used by the switch as the next hop and sent out the trunk port.

Checks

Review the HP FlexFabric Switch configuration and ensure all user-facing or untrusted ports are configured as access port.

If any of the user-facing switch ports are configured as a trunk, this is a finding

[HP]display current-configuration interface gigabitEthernet 1/0/1

Brief information on interface(s) under bridge mode:

Link: ADM - administratively down; Stby - standby
Speed or Duplex: (a)/A - auto; H - half; F - full
Type: A - access; T - trunk; H - hybrid
Interface Link Speed Duplex Type PVID Description
XGE1/0/1 UP 1G(a) F(a) A 100
XGE1/0/2 UP 1G(a) F(a) A 100
XGE1/0/3 UP 1G(a) F(a) A 100
XGE1/0/4 UP 1G(a) F(a) A 100

Fix

Configure all user-facing or untrusted ports as access ports.

[HP-GigabitEthernet1/0/13]port link-type access
V-66095 No Change
Findings ID: HFFS-L2-000029 Rule ID: SV-80585r1_rule Severity: medium CCI: CCI-000366

Discussion

VLAN hopping can be initiated by an attacker who has access to a switch port belonging to the same VLAN as the native VLAN of the trunk link connecting to another switch that the victim is connected to. If the attacker knows the victim’s MAC address, it can forge a frame with two 802.1q tags and a layer 2 header with the destination address of the victim. Since the frame will ingress the switch from a port belonging to its native VLAN, the trunk port connecting to the victim’s switch will simply remove the outer tag because native VLAN traffic is to be untagged. The switch will forward the frame on to the trunk link unaware of the inner tag with a VLAN ID of which the victim’s switch port is a member.

Checks

Review the HP FlexFabric Switch configurations and examine all trunk links. Verify the native VLAN has been configured to a VLAN ID other than the default VLAN 1. Connect to switch via console or SSH.

<HP> display current interface Bridge-Aggregation
#
interface Bridge-Aggregation1
description To-DistroEast(10G)
port link-type trunk
undo port trunk permit vlan 1
port trunk permit vlan 2100 to 2102 4017
port trunk pvid vlan 4017
link-aggregation mode dynamic

If any of the trunk links are assigned to VLAN 1, this is a finding.

Fix

Configure the ID of the native vlan on all trunk port(s).

[HP-GigabitEthernet1/0/13] undo port trunk permit vlan 1
[HP-GigabitEthernet1/0/13]port trunk pvid vlan 4017
V-66097 No Change
Findings ID: HFFS-L2-000030 Rule ID: SV-80587r1_rule Severity: medium CCI: CCI-000366

Discussion

Double encapsulation can be initiated by an attacker who has access to a switch port belonging to the native VLAN of the trunk port. Knowing the victim’s MAC address and with the victim attached to a different switch belonging to the same trunk group, thereby requiring the trunk link and frame tagging, the malicious user can begin the attack by sending frames with two sets of tags. The outer tag that will have the attacker’s VLAN ID (probably the well-known and omnipresent default VLAN) is stripped off by the switch, and the inner tag that will have the victim’s VLAN ID is used by the switch as the next hop and sent out the trunk port.

Checks

Verify all access switch ports are not part of the native VLAN (VLAN 1).

If any access switch port is assigned to the native VLAN (VLAN 1), this is a finding.

<HP>display interface GigabitEthernet brief

Brief information on interface(s) under bridge mode:
Link: ADM - administratively down; Stby - standby
Speed or Duplex: (a)/A - auto; H - half; F - full
Type: A - access; T - trunk; H - hybrid
Interface Link Speed Duplex Type PVID Description
GE1/0/1 UP 1G(a) F(a) A 1
GE1/0/2 UP 1G(a) F(a) A 100
GE1/0/3 UP 10M(a) F(a) A 100
XGE1/0/1 UP 10G(a) F(a) A 200
XGE1/0/2 UP 10G(a) F(a) A 200

If any access switch port are configured for the native vlan. This is a finding.

Fix

Remove the native vlan of the trunk ports.

[HP-GigabitEthernet1/0/1] undo port trunk permit vlan 1
V-66055 Removed
Findings ID: HFFS-L2-000004 Rule ID: SV-80545r1_rule Severity: medium CCI: CCI-001967

Discussion

Eliminating unauthorized access to the network from inside the enclave is vital to keeping a network secure. Internal access to the private network is enabled by simply connecting a workstation or laptop to a wall plate or access point located in the work area.

Checks

Review the configuration for all host-facing access switch ports and verify that re-authentication is specified to occur every 60 minutes or less. If 802.1x re-authentication does not occur every 60 minutes or less, this is a finding. display dot1x interface Ten-GigabitEthernet 1/0/7 802.1X protocol is enabled globally EAP authentication is enabled Configuration: Transmit Period 30 s, Handshake Period 15 s Quiet Period 60 s, Quiet Timer is disabled Supp Timeout 30 s, Server Timeout 100 s Reauth Period 3600 s Max attempts for sending an authentication request 2 Max number of 802.1X users is 2048 per slot Current number of online 802.1X users is 0 Ten-GigabitEthernet1/0/7 is link-down 802.1X protocol is enabled Handshake is enabled 802.1X unicast-trigger is disabled Periodic reauthentication is enabled

Fix

Configure the 802.1x implementation on all host-facing access switch ports to enable re-authentication every 60 minutes or less. [HP] gigabitEthernet1/0/1 [HP-GigabitEthernet1/0/1] dot1x re-authenticate