| Finding ID |
Severity |
Title |
Description |
|
V-220649
|
High |
The Cisco switch must uniquely identify and authenticate 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. |
|
V-220672
|
Medium |
The Cisco 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-220671
|
Medium |
The Cisco 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-220670
|
Medium |
The Cisco 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-220669
|
Medium |
The Cisco 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-220668
|
Medium |
The Cisco 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-220667
|
Medium |
The Cisco 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-220666
|
Medium |
The Cisco 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-220665
|
Medium |
The Cisco 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-220664
|
Medium |
The Cisco 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... |
|
V-220661
|
Medium |
The Cisco 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-220660
|
Medium |
The Cisco 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... |
|
V-220659
|
Medium |
The Cisco 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-220658
|
Medium |
The Cisco switch must have Unknown Unicast Flood Blocking (UUFB) 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 Address Resolution Protocol (ARP) entry for a destination host and forwards it to the access layer... |
|
V-220657
|
Medium |
The Cisco switch must have STP Loop Guard enabled. |
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-220656
|
Medium |
The Cisco switch must have BPDU Guard enabled on all user-facing or untrusted access switch 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 STP PortFast BPDU... |
|
V-220651
|
Medium |
The Cisco 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 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-220650
|
Medium |
The Cisco switch must authenticate all VLAN Trunk Protocol (VTP) messages with a hash function using the most secured cryptographic algorithm available. |
VLAN Trunk Protocol (VTP) provides central management of VLAN domains, thus reducing administration in a switched network. When configuring a new VLAN on a VTP server, the VLAN is distributed through all switches in the domain. This reduces the need to configure the same VLAN everywhere. VTP pruning preserves bandwidth... |
|
V-220673
|
Low |
The Cisco switch must not have any switchports 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-220663
|
Low |
The Cisco 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-220662
|
Low |
The Cisco switch must have Storm Control configured on all host-facing switchports. |
A traffic storm occurs when packets flood a LAN, creating excessive traffic and degrading network performance. Traffic storm control prevents network disruption by suppressing ingress traffic when the number of packets reaches a configured threshold levels. Traffic storm control monitors ingress traffic levels on a port and drops traffic when... |
|
V-220655
|
Low |
The Cisco switch must have Root Guard enabled on all switch ports connecting to access layer switches. |
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... |