Cisco NX OS Switch RTR Security Technical Implementation Guide
Rules, Groups, and Values defined within the XCCDF Benchmark
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SRG-NET-000343-RTR-000002
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The Cisco Multicast Source Discovery Protocol (MSDP) switch must be configured to authenticate all received MSDP packets.
MSDP peering with customer network switches presents additional risks to the core, whether from a rogue or misconfigured MSDP-enabled switch. MSDP password authentication is used to validate each s...Rule Medium Severity -
SRG-NET-000018-RTR-000007
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SRG-NET-000018-RTR-000008
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The Cisco Multicast Source Discovery Protocol (MSDP) switch must be configured to filter source-active multicast advertisements to external MSDP peers to avoid global visibility of local-only multicast sources and groups.
To avoid global visibility of local information, there are a number of source-group (S, G) states in a PIM-SM domain that must not be leaked to another domain, such as multicast sources with privat...Rule Low Severity -
SRG-NET-000018-RTR-000009
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The Cisco Multicast Source Discovery Protocol (MSDP) switch must be configured to limit the amount of source-active messages it accepts on a per-peer basis.
To reduce any risk of a denial-of-service (DoS) attack from a rogue or misconfigured MSDP switch, the switch must be configured to limit the number of source-active messages it accepts from each peer.Rule Low Severity -
SRG-NET-000512-RTR-000011
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SRG-NET-000512-RTR-000012
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The Cisco switch must be configured to advertise a hop limit of at least 32 in Switch Advertisement messages for IPv6 stateless auto-configuration deployments.
The Neighbor Discovery protocol allows a hop limit value to be advertised by routers in a Router Advertisement message being used by hosts instead of the standardized default value. If a very small...Rule Low Severity -
SRG-NET-000512-RTR-000013
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SRG-NET-000512-RTR-000014
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The Cisco perimeter switch must be configured to suppress Router Advertisements on all external IPv6-enabled interfaces.
Many of the known attacks in stateless autoconfiguration are defined in RFC 3756 were present in IPv4 ARP attacks. To mitigate these vulnerabilities, links that have no hosts connected such as the ...Rule Medium Severity -
The Cisco switch must be configured to implement message authentication for all control plane protocols.
A rogue switch could send a fictitious routing update to convince a site's perimeter switch to send traffic to an incorrect or even a rogue destination. This diverted traffic could be analyzed to l...Rule Medium Severity -
The Cisco switch must be configured to use encryption for routing protocol authentication.
A rogue switch could send a fictitious routing update to convince a site's perimeter switch to send traffic to an incorrect or even a rogue destination. This diverted traffic could be analyzed to l...Rule Medium Severity -
The Cisco switch must be configured to authenticate all routing protocol messages using NIST-validated FIPS 198-1 message authentication code algorithm.
A rogue switch could send a fictitious routing update to convince a site's perimeter switch to send traffic to an incorrect or even a rogue destination. This diverted traffic could be analyzed to l...Rule Medium Severity -
The Cisco switch must not be configured to have any feature enabled that calls home to the vendor.
Call home services will routinely send data such as configuration and diagnostic information to the vendor for routine or emergency analysis and troubleshooting. There is a risk that transmission o...Rule Medium Severity -
The Cisco switch must be configured to have Gratuitous ARP disabled on all external interfaces.
A gratuitous ARP is an ARP broadcast in which the source and destination MAC addresses are the same. It is used to inform the network about a host IP address. A spoofed gratuitous ARP message can c...Rule Medium Severity -
The Cisco switch must be configured to have IP directed broadcast disabled on all interfaces.
An IP directed broadcast is a datagram sent to the broadcast address of a subnet that is not directly attached to the sending machine. The directed broadcast is routed through the network as a unic...Rule Low Severity -
The Cisco perimeter switch must be configured to deny network traffic by default and allow network traffic by exception.
A deny-all, permit-by-exception network communications traffic policy ensures that only connections that are essential and approved are allowed. This requirement applies to both inbound and outbou...Rule High Severity -
The Cisco perimeter switch must be configured to restrict it from accepting outbound IP packets that contain an illegitimate address in the source address field via egress filter or by enabling Unicast Reverse Path Forwarding (uRPF).
A compromised host in an enclave can be used by a malicious platform to launch cyberattacks on third parties. This is a common practice in "botnets", which are a collection of compromised computers...Rule High Severity -
The Cisco perimeter switch must be configured to filter traffic destined to the enclave in accordance with the guidelines contained in DoD Instruction 8551.1.
Vulnerability assessments must be reviewed by the System Administrator, and protocols must be approved by the Information Assurance (IA) staff before entering the enclave. ACLs are the first line ...Rule Medium Severity -
The Cisco perimeter switch must be configured to filter egress traffic at the internal interface on an inbound direction.
Access lists are used to separate data traffic into that which it will route (permitted packets) and that which it will not route (denied packets). Secure configuration of switches makes use of acc...Rule Medium Severity -
The Cisco perimeter switch must be configured to block all packets with any IP options.
Packets with IP options are not fast switched and henceforth must be punted to the switch processor. Hackers who initiate denial-of-service (DoS) attacks on switches commonly send large streams of ...Rule Medium Severity -
The Cisco perimeter switch must be configured to have Cisco Discovery Protocol (CDP) disabled on all external interfaces.
CDP is a Cisco proprietary neighbor discovery protocol used to advertise device capabilities, configuration information, and device identity. CDP is media-and-protocol-independent as it runs over l...Rule Low Severity -
The Cisco perimeter switch must be configured to have Proxy ARP disabled on all external interfaces.
When Proxy ARP is enabled on a switch, it allows that switch to extend the network (at Layer 2) across multiple interfaces (LAN segments). Because proxy ARP allows hosts from different LAN segments...Rule Medium Severity -
The Cisco switch must be configured to only permit management traffic that ingresses and egresses the out-of-band management (OOBM) interface.
The OOBM access switch will connect to the management interface of the managed network elements. The management interface can be a true OOBM interface or a standard interface functioning as the man...Rule Medium Severity -
The Cisco BGP switch must be configured to check whether a single-hop eBGP peer is directly connected.
As described in RFC 3682, GTSM is designed to protect a switch's IP-based control plane from DoS attacks. Many attacks focused on CPU load and line-card overload can be prevented by implementing GT...Rule Low Severity -
The Cisco BGP switch must be configured to use a unique key for each autonomous system (AS) that it peers with.
If the same keys are used between eBGP neighbors, the chance of a hacker compromising any of the BGP sessions increases. It is possible that a malicious user exists in one autonomous system who wou...Rule Medium Severity -
The Cisco BGP switch must be configured to reject route advertisements from BGP peers that do not list their autonomous system (AS) number as the first AS in the AS_PATH attribute.
Verifying the path a route has traversed will ensure the IP core is not used as a transit network for unauthorized or possibly even internet traffic. All autonomous system boundary switches (ASBRs)...Rule Low Severity -
The Cisco BGP switch must be configured to use the maximum prefixes feature to protect against route table flooding and prefix de-aggregation attacks.
The effects of prefix de-aggregation can degrade switch performance due to the size of routing tables and also result in black-holing legitimate traffic. Initiated by an attacker or a misconfigured...Rule Medium Severity -
The Cisco BGP switch must be configured to use its loopback address as the source address for iBGP peering sessions.
Using a loopback address as the source address offers a multitude of uses for security, access, management, and scalability of the BGP switches. It is easier to construct appropriate ingress filter...Rule Low Severity -
The Cisco MPLS switch must be configured to synchronize Interior Gateway Protocol (IGP) and LDP to minimize packet loss when an IGP adjacency is established prior to LDP peers completing label exchange.
Packet loss can occur when an IGP adjacency is established and the switch begins forwarding packets using the new adjacency before the LDP label exchange completes between the peers on that link. P...Rule Low Severity -
The MPLS switch with RSVP-TE enabled must be configured with message pacing to adjust maximum burst and maximum number of RSVP messages to an output queue based on the link speed and input queue size of adjacent core switches.
RSVP-TE can be used to perform constraint-based routing when building LSP tunnels within the network core that will support QoS and traffic engineering requirements. RSVP-TE is also used to enable ...Rule Low Severity -
The Cisco MPLS switch must be configured to have TTL Propagation disabled.
The head end of the label-switched path (LSP), the label edge switch (LER) will decrement the IP packet's time-to-live (TTL) value by one and then copy the value to the MPLS TTL field. At each labe...Rule Medium Severity -
The Cisco PE switch must be configured to have each Virtual Routing and Forwarding (VRF) instance with the appropriate Route Target (RT).
The primary security model for an MPLS L3VPN as well as a VRF-lite infrastructure is traffic separation. Each interface can only be associated to one VRF, which is the fundamental framework for tra...Rule High Severity -
The Cisco PE switch must be configured to have each VRF with the appropriate Route Distinguisher (RD).
An RD provides uniqueness to the customer address spaces within the MPLS L3VPN infrastructure. The concept of the VPN-IPv4 and VPN-IPv6 address families consists of the RD prepended before the IP a...Rule Medium Severity -
The Cisco PE switch providing MPLS Layer 2 Virtual Private Network (L2VPN) services must be configured to authenticate targeted Label Distribution Protocol (LDP) sessions used to exchange virtual circuit (VC) information using a FIPS-approved message authentication code algorithm.
LDP provides the signaling required for setting up and tearing down pseudowires (virtual circuits used to transport Layer 2 frames) across an MPLS IP core network. Using a targeted LDP session, eac...Rule Medium Severity -
The Cisco PE switch providing MPLS Virtual Private Wire Service (VPWS) must be configured to have the appropriate virtual circuit identification (VC ID) for each attachment circuit.
VPWS is an L2VPN technology that provides a virtual circuit between two PE switches to forward Layer 2 frames between two customer-edge switches or switches through an MPLS-enabled IP core. The ing...Rule High Severity -
The Cisco PE switch providing Virtual Private LAN Services (VPLS) must be configured to have all attachment circuits defined to the virtual forwarding instance (VFI) with the globally unique VPN ID assigned for each customer VLAN.
VPLS defines an architecture that delivers Ethernet multipoint services over an MPLS network. Customer Layer 2 frames are forwarded across the MPLS core via pseudowires using IEEE 802.1q Ethernet b...Rule High Severity -
The Cisco PE switch providing Virtual Private LAN Services (VPLS) must be configured to have traffic storm control thresholds on CE-facing interfaces.
A traffic storm occurs when packets flood a VPLS bridge, creating excessive traffic and degrading network performance. Traffic storm control prevents VPLS bridge disruption by suppressing traffic w...Rule Medium Severity -
The Cisco PE switch must be configured to implement Internet Group Management Protocol (IGMP) or Multicast Listener Discovery (MLD) snooping for each Virtual Private LAN Services (VPLS) bridge domain.
IGMP snooping provides a way to constrain multicast traffic at Layer 2. By monitoring the IGMP membership reports sent by hosts within the bridge domain, the snooping application can set up Layer 2...Rule Low Severity -
The Cisco PE switch must be configured to limit the number of MAC addresses it can learn for each Virtual Private LAN Services (VPLS) bridge domain.
VPLS defines an architecture that delivers Ethernet multipoint services over an MPLS network. Customer Layer 2 frames are forwarded across the MPLS core via pseudowires using IEEE 802.1q Ethernet b...Rule Medium Severity -
The Cisco PE switch must be configured to block any traffic that is destined to the IP core infrastructure.
IP/MPLS networks providing VPN and transit services must provide, at the least, the same level of protection against denial-of-service (DoS) attacks and intrusions as Layer 2 networks. Although the...Rule High Severity -
The Cisco PE switch must be configured to ignore or drop all packets with any IP options.
Packets with IP options are not fast-switched and therefore must be punted to the switch processor. Hackers who initiate denial-of-service (DoS) attacks on switches commonly send large streams of p...Rule Medium Severity -
The Cisco PE switch must be configured to enforce a Quality-of-Service (QoS) policy to provide preferred treatment for mission-critical applications.
Different applications have unique requirements and toleration levels for delay, jitter, bandwidth, packet loss, and availability. To manage the multitude of applications and services, a network re...Rule Low Severity -
The Cisco P switch must be configured to enforce a Quality-of-Service (QoS) policy to provide preferred treatment for mission-critical applications.
Different applications have unique requirements and toleration levels for delay, jitter, bandwidth, packet loss, and availability. To manage the multitude of applications and services, a network re...Rule Low Severity -
The Cisco switch must be configured to enforce a Quality-of-Service (QoS) policy to limit the effects of packet flooding denial-of-service (DoS) attacks.
DoS is a condition when a resource is not available for legitimate users. Packet flooding distributed denial-of-service (DDoS) attacks are referred to as volumetric attacks and have the objective o...Rule Medium Severity -
The Cisco multicast switch must be configured to disable Protocol Independent Multicast (PIM) on all interfaces that are not required to support multicast routing.
If multicast traffic is forwarded beyond the intended boundary, it is possible that it can be intercepted by unauthorized or unintended personnel. Limiting where, within the network, a given multic...Rule Medium Severity -
The Cisco multicast edge switch must be configured to establish boundaries for administratively scoped multicast traffic.
If multicast traffic is forwarded beyond the intended boundary, it is possible that it can be intercepted by unauthorized or unintended personnel. Administrative scoped multicast addresses are loc...Rule Low Severity
Node 2
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