HP FlexFabric Switch L2S Security Technical Implementation Guide

U_HP_FlexFabric_Switch_L2S_STIG_V1R2_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]
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Version / Release: V1R2

Published: 2018-12-21

Updated At: 2019-01-27 14:54:39

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Vuln Rule Version CCI Severity Title Description
SV-80451r1_rule HFFS-L2-000001 CCI-000381 MEDIUM The HP FlexFabric Switch must be configured to disable non-essential capabilities. 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.
SV-80541r1_rule HFFS-L2-000002 CCI-001958 HIGH HP FlexFabric Switch must authenticate all network-connected endpoint devices before establishing any connection. 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.
SV-80543r1_rule HFFS-L2-000003 CCI-001967 MEDIUM HP FlexFabric Switch must authenticate all endpoint devices before establishing a network connection using bidirectional authentication that is cryptographically based. 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.
SV-80547r1_rule HFFS-L2-000006 CCI-001095 MEDIUM The HP FlexFabric Switch must manage excess bandwidth to limit the effects of packet flooding types of denial of service (DoS) attacks. 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).
SV-80549r1_rule HFFS-L2-000008 CCI-001919 MEDIUM The HP FlexFabric Switch must provide the capability for authorized users to select a user session to capture. 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.
SV-80551r1_rule HFFS-L2-000009 CCI-001920 MEDIUM The HP FlexFabric Switch must provide the capability for authorized users to remotely view, in real time, all content related to an established user session from a component separate from the HP FlexFabric Switch. 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.
SV-80553r1_rule HFFS-L2-000010 CCI-002385 MEDIUM The HP FlexFabric Switch must have Root Guard enabled on all ports where the root bridge should not appear. 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.
SV-80555r1_rule HFFS-L2-000011 CCI-002385 MEDIUM The HP FlexFabric Switch must have BPDU Guard enabled on all user-facing access ports. 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.
SV-80557r1_rule HFFS-L2-000012 CCI-002385 MEDIUM The HP FlexFabric Switch must have STP Loop Protection enabled all non-designated STP switch ports. 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.
SV-80559r1_rule HFFS-L2-000013 CCI-002385 MEDIUM The HP FlexFabric Switch must have unknown storm-constrain enabled. 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.
SV-80561r1_rule HFFS-L2-000014 CCI-002385 MEDIUM The HP FlexFabric Switch must have DHCP snooping for all user VLANs to validate DHCP messages from untrusted sources as well as rate-limit DHCP traffic. 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.
SV-80563r1_rule HFFS-L2-000015 CCI-002385 MEDIUM The HP FlexFabric Switch must have IP Source Guard enabled on all user-facing or untrusted access switch ports. 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.
SV-80565r1_rule HFFS-L2-000016 CCI-002385 MEDIUM The HP FlexFabric Switch must have Dynamic ARP Inspection (DAI) enabled on all user VLANs. 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.
SV-80567r1_rule HFFS-L2-000020 CCI-000366 MEDIUM The HP FlexFabric Switch must implement Rapid STP where VLANs span multiple switches with redundant links. 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.
SV-80569r1_rule HFFS-L2-000021 CCI-000366 MEDIUM The HP FlexFabric Switch must enable Device Link Detection Protocol (DLDP) to protect against one-way connections. 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.
SV-80571r1_rule HFFS-L2-000022 CCI-000366 MEDIUM The HP FlexFabric Switch must have all trunk links enabled statically. 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.
SV-80573r1_rule HFFS-L2-000023 CCI-000366 MEDIUM The HP FlexFabric Switch must only allow a maximum of one registered MAC address per access port. 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.
SV-80575r1_rule HFFS-L2-000024 CCI-000366 MEDIUM The HP FlexFabric Switch must have all disabled switch ports assigned an unused VLAN. 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.
SV-80577r1_rule HFFS-L2-000025 CCI-000366 MEDIUM The HP FlexFabric Switch must not have the default VLAN assigned to any host-facing switch ports. 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.
SV-80579r1_rule HFFS-L2-000026 CCI-000366 MEDIUM The HP FlexFabric Switch must have the default VLAN pruned from all trunk ports that do not require it. 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.
SV-80581r1_rule HFFS-L2-000027 CCI-000366 MEDIUM The HP FlexFabric Switch must not use the default VLAN for management traffic. 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.
SV-80583r1_rule HFFS-L2-000028 CCI-000366 MEDIUM The HP FlexFabric Switch must have all user-facing or untrusted ports configured as access switch ports. 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.
SV-80585r1_rule HFFS-L2-000029 CCI-000366 MEDIUM The HP FlexFabric Switch must have the native VLAN assigned to a VLAN ID other than the default VLAN ID for all 802.1q trunk links. 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.
SV-80587r1_rule HFFS-L2-000030 CCI-000366 MEDIUM The HP FlexFabric Switch must not have any access switch ports assigned to the native VLAN. 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.