STIGQter: STIG Summary: Cisco IOS XR Router RTR Security Technical Implementation Guide Version: 2 Release: 1 Benchmark Date: 23 Oct 2020:

The Cisco BGP router must be configured to reject outbound route advertisements for any prefixes that do not belong to any customers or the local autonomous system (AS).

DISA Rule

SV-216780r531087_rule

Vulnerability Number

V-216780

Group Title

SRG-NET-000018-RTR-000005

Rule Version

CISC-RT-000520

Severity

CAT II

CCI(s)

• CCI-001368 - The information system enforces approved authorizations for controlling the flow of information within the system based on organization-defined information flow control policies.

Weight

10

Fix Recommendation

This requirement is not applicable for the DODIN Backbone.

Step 1: Configure a prefix set for customer and local autonomous system prefixes as shown in the example.

RP/0/0/CPU0:R2(config)#prefix-set CE_PREFIX_ADVERTISEMENTS
RP/0/0/CPU0:R2(config-pfx)#x.13.1.0/24 le 32,
RP/0/0/CPU0:R2(config-pfx)#x.13.2.0/24 le 32,
RP/0/0/CPU0:R2(config-pfx)#x.13.3.0/24 le 32,
RP/0/0/CPU0:R2(config-pfx)#x.13.4.0/24 le 32
RP/0/0/CPU0:R2(config-pfx)#end-set

Step 2: Configure a route policy filter for allow customer and local autonomous system prefixes as shown in the example.

RP/0/0/CPU0:R2(config)#route-policy CE_ADVERTISEMENTS
RP/0/0/CPU0:R2(config-rpl)#if destination in CE_PREFIX_ADVERTISEMENTS then
RP/0/0/CPU0:R2(config-rpl-if)#pass
RP/0/0/CPU0:R2(config-rpl-if)#else
RP/0/0/CPU0:R2(config-rpl-else)#drop
RP/0/0/CPU0:R2(config-rpl-else)#endif
RP/0/0/CPU0:R2(config-rpl)#end-policy

Step 3: Apply the route policy to each customer neighbor as shown in the example.

RP/0/0/CPU0:R2(config)#router bgp xx
RP/0/0/CPU0:R2(config-bgp)#neighbor x.12.4.14
RP/0/0/CPU0:R2(config-bgp-nbr)#address-family ipv4 unicast
RP/0/0/CPU0:R2(config-bgp-nbr-af)#route-policy route-policy CE_ADVERTISEMENTS out
RP/0/0/CPU0:R2(config-bgp)#neighbor x.12.4.16
RP/0/0/CPU0:R2(config-bgp-nbr)#address-family ipv4 unicast
RP/0/0/CPU0:R2(config-bgp-nbr-af)#route-policy CE_ADVERTISEMENTS out
RP/0/0/CPU0:R2(config-bgp-nbr-af)#end

Check Contents

This requirement is not applicable for the DODIN Backbone.

Step 1: verify that an outbound route policy has been configured for each customer neighbor as shown in the example below.

router bgp xx
address-family ipv4 unicast
!
neighbor x.12.4.14
remote-as 64514
address-family ipv4 unicast
route-policy CE_ADVERTISEMENTS out
!
!
neighbor x.12.4.16
remote-as 64516
address-family ipv4 unicast
route-policy CE_ADVERTISEMENTS out
!
!

Step 2: Review the route policy to determine if it is accepting only prefixes belonging to customers or the local autonomous system as shown in the example below.

route-policy CE_ADVERTISEMENTS
if destination in CE_PREFIX_ADVERTISEMENTS then
pass
else
drop
endif
end-policy

Step 3: Review the prefix sets referenced in the route policy above to determine if they include only prefixes belonging to customers or the local autonomous system as shown in the example below.

prefix-set CE_PREFIX_ADVERTISEMENTS
x.13.1.0/24 le 32,
x.13.2.0/24 le 32,
x.13.3.0/24 le 32,
x.13.4.0/24 le 32
end-set

If the router is not configured to reject outbound route advertisements that do not belong to any customers or the local AS, this is a finding.

Vulnerability Number

V-216780

Documentable

False

Rule Version

CISC-RT-000520

Severity Override Guidance

This requirement is not applicable for the DODIN Backbone.

Step 1: verify that an outbound route policy has been configured for each customer neighbor as shown in the example below.

router bgp xx
address-family ipv4 unicast
!
neighbor x.12.4.14
remote-as 64514
address-family ipv4 unicast
route-policy CE_ADVERTISEMENTS out
!
!
neighbor x.12.4.16
remote-as 64516
address-family ipv4 unicast
route-policy CE_ADVERTISEMENTS out
!
!

Step 2: Review the route policy to determine if it is accepting only prefixes belonging to customers or the local autonomous system as shown in the example below.

route-policy CE_ADVERTISEMENTS
if destination in CE_PREFIX_ADVERTISEMENTS then
pass
else
drop
endif
end-policy

Step 3: Review the prefix sets referenced in the route policy above to determine if they include only prefixes belonging to customers or the local autonomous system as shown in the example below.

prefix-set CE_PREFIX_ADVERTISEMENTS
x.13.1.0/24 le 32,
x.13.2.0/24 le 32,
x.13.3.0/24 le 32,
x.13.4.0/24 le 32
end-set

If the router is not configured to reject outbound route advertisements that do not belong to any customers or the local AS, this is a finding.

Check Content Reference

M

Target Key

4029

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