| Finding ID |
Severity |
Title |
Description |
|
V-255968
|
High |
The Arista MLS layer 2 switch must uniquely identify all network-connected endpoint devices before establishing any connection. |
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.
Satisfies: SRG-NET-000148-L2S-000015, SRG-NET-000343-L2S-000016 |
|
V-255985
|
Medium |
The Arista MLS layer 2 switch must have the native VLAN assigned to an ID other than the default VLAN 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... |
|
V-255984
|
Medium |
The Arista MLS layer 2 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... |
|
V-255983
|
Medium |
The Arista MLS layer 2 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... |
|
V-255982
|
Medium |
The Arista MLS layer 2 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... |
|
V-255981
|
Medium |
The Arista MLS layer 2 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... |
|
V-255980
|
Medium |
The Arista MLS layer 2 switch must have all disabled switch ports assigned to 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. |
|
V-255979
|
Medium |
The Arista MLS layer 2 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... |
|
V-255978
|
Medium |
The Arista MLS layer 2 switch must enable Unidirectional Link Detection (UDLD) 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. UDLD is a layer 2 protocol... |
|
V-255977
|
Medium |
The Arista MLS layer 2 Arista MLS 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 Multiple Spanning-Tree (802.1s) instead... |
|
V-255975
|
Medium |
The Arista MLS layer 2 switch must have Dynamic Address Resolution Protocol (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... |
|
V-255974
|
Medium |
The Arista MLS layer 2 switch must have IP Source Guard enabled on all user-facing or untrusted access switch ports. |
IP Source Guard (IPSG) 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... |
|
V-255973
|
Medium |
The Arista MLS layer 2 switch must have DHCP snooping for all user VLANs to validate DHCP messages from untrusted sources. |
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 DHCP servers are considered untrusted sources. An unknown DHCP server on the network on an untrusted port is called a spurious DHCP server, any... |
|
V-255972
|
Medium |
The Arista MLS switch must have STP Loop Guard enabled on all nondesignated STP switch ports. |
The Spanning Tree Protocol (STP) loop guard 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... |
|
V-255971
|
Medium |
The Arista MLS layer 2 switch must have BPDU Guard enabled on all switch ports connecting to access layer switches and hosts. |
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 STP PortFast BPDU... |
|
V-255969
|
Medium |
The Arista MLS layer 2 switch must be configured for Storm Control 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 distributed DoS (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... |
|
V-255986
|
Low |
The Arista MLS layer 2 switch must not have any 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... |
|
V-255976
|
Low |
The Arista MLS layer 2 switch must have IGMP or MLD Snooping configured on all VLANs. |
IGMP and MLD snooping provides a way to constrain multicast traffic at Layer 2. By monitoring the IGMP or MLD membership reports sent by hosts within a VLAN, the snooping application can set up Layer 2 multicast forwarding tables to deliver specific multicast traffic only to interfaces connected to hosts... |
|
V-255970
|
Low |
The Arista MLS switch must have Root Guard enabled on all switch ports connecting to access layer switches and hosts. |
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... |
