Cisco IOS XE Switch RTR Security Technical Implementation Guide
Rules, Groups, and Values defined within the XCCDF Benchmark
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SRG-NET-000362-RTR-000113
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The Cisco switch must be configured to have Internet Control Message Protocol (ICMP) unreachable messages disabled on all external interfaces.
The ICMP supports IP traffic by relaying information about paths, routes, and network conditions. Switches automatically send ICMP messages under a wide variety of conditions. Host unreachable ICMP...Rule Medium Severity -
SRG-NET-000362-RTR-000114
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The Cisco switch must be configured to have Internet Control Message Protocol (ICMP) mask reply messages disabled on all external interfaces.
The ICMP supports IP traffic by relaying information about paths, routes, and network conditions. Switches automatically send ICMP messages under a wide variety of conditions. Mask Reply ICMP messa...Rule Medium Severity -
SRG-NET-000362-RTR-000115
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SRG-NET-000077-RTR-000001
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The Cisco switch must be configured to produce audit records containing information to establish the source of the events.
Without establishing the source of the event, it is impossible to establish, correlate, and investigate the events leading up to an outage or attack. In order to compile an accurate risk assessmen...Rule Medium Severity -
SRG-NET-000019-RTR-000001
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SRG-NET-000202-RTR-000001
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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 -
SRG-NET-000019-RTR-000002
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The Cisco perimeter switch must be configured to enforce approved authorizations for controlling the flow of information between interconnected networks in accordance with applicable policy.
Information flow control regulates authorized information to travel within a network and between interconnected networks. Controlling the flow of network traffic is critical so it does not introduc...Rule Medium Severity -
SRG-NET-000364-RTR-000109
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The Cisco BGP switch must be configured to reject inbound route advertisements for any Bogon prefixes.
Accepting route advertisements for Bogon prefixes can result in the local autonomous system (AS) becoming a transit for malicious traffic as it will in turn advertise these prefixes to neighbor aut...Rule Medium Severity -
SRG-NET-000018-RTR-000003
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SRG-NET-000364-RTR-000110
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The Cisco perimeter switch must be configured to block inbound packets with source Bogon IP address prefixes.
Packets with Bogon IP source addresses should never be allowed to traverse the IP core. Bogon IP networks are RFC1918 addresses or address blocks that have never been assigned by the IANA or have b...Rule Medium Severity -
SRG-NET-000205-RTR-000014
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SRG-NET-000205-RTR-000003
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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 -
SRG-NET-000205-RTR-000004
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The Cisco BGP switch must be configured to reject inbound route advertisements for any prefixes belonging to the local autonomous system (AS).
Accepting route advertisements belonging to the local AS can result in traffic looping or being black-holed, or at a minimum, using a non-optimized path.Rule Medium Severity -
SRG-NET-000018-RTR-000004
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SRG-NET-000205-RTR-000005
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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 -
SRG-NET-000205-RTR-000015
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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 -
SRG-NET-000364-RTR-000111
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The Cisco perimeter switch must be configured to have Link Layer Discovery Protocol (LLDP) disabled on all external interfaces.
LLDP is a neighbor discovery protocol used to advertise device capabilities, configuration information, and device identity. LLDP is media-and-protocol-independent as it runs over layer 2; therefor...Rule Low Severity -
SRG-NET-000364-RTR-000111
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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 -
SRG-NET-000364-RTR-000112
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SRG-NET-000364-RTR-000113
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The Cisco perimeter switch must be configured to block all outbound management traffic.
For in-band management, the management network must have its own subnet in order to enforce control and access boundaries provided by Layer 3 network nodes, such as switches and firewalls. Manageme...Rule Medium Severity -
SRG-NET-000205-RTR-000012
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SRG-NET-000362-RTR-000124
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The Cisco BGP switch must be configured to enable the Generalized TTL Security Mechanism (GTSM).
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 -
SRG-NET-000230-RTR-000002
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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 -
SRG-NET-000018-RTR-000002
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SRG-NET-000018-RTR-000005
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SRG-NET-000205-RTR-000006
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The Cisco BGP switch must be configured to reject outbound route advertisements for any prefixes belonging to the IP core.
Outbound route advertisements belonging to the core can result in traffic either looping or being black holed, or at a minimum, using a nonoptimized path.Rule Medium Severity -
SRG-NET-000018-RTR-000006
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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 -
SRG-NET-000018-RTR-000010
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The Cisco BGP switch must be configured to reject route advertisements from CE switches with an originating AS in the AS_PATH attribute that does not belong to that customer.
Verifying the path a route has traversed will ensure that the local AS is not used as a transit network for unauthorized traffic. To ensure that the local AS does not carry any prefixes that do not...Rule Low Severity -
SRG-NET-000362-RTR-000117
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SRG-NET-000362-RTR-000118
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The Cisco BGP switch must be configured to limit the prefix size on any inbound route advertisement to /24, or the least significant prefixes issued to the customer.
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 Low Severity
Node 2
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