The Juniper perimeter router must be configured to protect an enclave connected to an alternate gateway by using an inbound filter that only permits packets with destination addresses within the site's address space.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-253989	JUEX-RT-000170	SV-253989r997520_rule		High

Description
Enclaves with alternate gateway connections must take additional steps to ensure there is no compromise on the enclave network or NIPRNet. Without verifying the destination address of traffic coming from the site's alternate gateway, the perimeter router could be routing transit data from the internet into the NIPRNet. This could also make the perimeter router vulnerable to a denial-of-service (DoS) attack as well as provide a back door into the NIPRNet. The DOD enclave must ensure the ingress filter applied to external interfaces on a perimeter router connecting to an Approved Gateway is secure through filters permitting packets with a destination address belonging to the DOD enclave's address block.

Description

Enclaves with alternate gateway connections must take additional steps to ensure there is no compromise on the enclave network or NIPRNet. Without verifying the destination address of traffic coming from the site's alternate gateway, the perimeter router could be routing transit data from the internet into the NIPRNet. This could also make the perimeter router vulnerable to a denial-of-service (DoS) attack as well as provide a back door into the NIPRNet. The DOD enclave must ensure the ingress filter applied to external interfaces on a perimeter router connecting to an Approved Gateway is secure through filters permitting packets with a destination address belonging to the DOD enclave's address block.

STIG	Date
Juniper EX Series Switches Router Security Technical Implementation Guide	2024-06-10

Details

Check Text ( C-57441r843998_chk )
This requirement is not applicable for the DODIN Backbone. Review the configuration of each router interface connecting to an alternate gateway. Verify each permit statement of the ingress filter only permits packets with destination addresses of the site's NIPRNet address space or a destination address belonging to the address block assigned by the alternate gateway network service provider. Verify each permit statement "from" stanza (filter match conditions) references either the "destination-address" or "destination-prefix-list" directive. Using prefix lists makes management easier because managing interior addresses must only be configured in one location (the prefix-list) vice many locations (each permitting filter term). For example: [edit policy-options] prefix-list inside_addresses-ipv4 { ; } prefix-list inside_addresses-ipv6 { ; } [edit firewall] family inet { filter inbound-ipv4 { ; permit-term1 { from { ; destination-prefix-list inside_addresses-ipv4; } then accept; } } } family inet6 { filter inbound-ipv6 { ; permit-term1 { from { ; destination-prefix-list inside_addresses-ipv6; } then accept; } } } Verify the filter is applied inbound on exterior-facing interfaces. For example: [edit interfaces] { unit { family inet { filter { input inbound-ipv4; } address ; } family inet6 { filter { input inbound-ipv6; } address ; } } } Note: Some Juniper devices support both monolithic filters and filter lists. Filter lists separate each term, or set of terms, into a separate filter that is applied sequentially to an interface. If using filter lists, the keywords "input" or "output" change to "input-list" or "output-list". Verify the final list item is a deny-all filter. If the ingress filter permits packets with addresses other than those specified, such as destination addresses of the site's NIPRNet address space or a destination address belonging to the address block assigned by the alternate gateway network service provider, this is a finding.

Check Text ( C-57441r843998_chk )

This requirement is not applicable for the DODIN Backbone.

Review the configuration of each router interface connecting to an alternate gateway.

Verify each permit statement of the ingress filter only permits packets with destination addresses of the site's NIPRNet address space or a destination address belonging to the address block assigned by the alternate gateway network service provider. Verify each permit statement "from" stanza (filter match conditions) references either the "destination-address" or "destination-prefix-list" directive. Using prefix lists makes management easier because managing interior addresses must only be configured in one location (the prefix-list) vice many locations (each permitting filter term). For example:
[edit policy-options]
prefix-list inside_addresses-ipv4 {
;
}
prefix-list inside_addresses-ipv6 {
;
}
[edit firewall]
family inet {
filter inbound-ipv4 {
;
permit-term1 {
from {
;
destination-prefix-list inside_addresses-ipv4;
}
then accept;
}

}
}
family inet6 {
filter inbound-ipv6 {
;
permit-term1 {
from {
;
destination-prefix-list inside_addresses-ipv6;
}
then accept;
}

}
}

Verify the filter is applied inbound on exterior-facing interfaces. For example:
[edit interfaces]
{
unit {
family inet {
filter {
input inbound-ipv4;
}
address ;
}
family inet6 {
filter {
input inbound-ipv6;
}
address ;
}
}
}

Note: Some Juniper devices support both monolithic filters and filter lists. Filter lists separate each term, or set of terms, into a separate filter that is applied sequentially to an interface. If using filter lists, the keywords "input" or "output" change to "input-list" or "output-list". Verify the final list item is a deny-all filter.

If the ingress filter permits packets with addresses other than those specified, such as destination addresses of the site's NIPRNet address space or a destination address belonging to the address block assigned by the alternate gateway network service provider, this is a finding.

Fix Text (F-57392r843999_fix)
This requirement is not applicable for the DODIN Backbone. Configure the ingress filter of the perimeter router connected to an alternate gateway to only permit packets with destination addresses of the site's NIPRNet address space or a destination address belonging to the address block assigned by the alternate gateway network service provider. For example: set policy-options prefix-list inside_addresses-ipv4 set policy-options prefix-list inside_addresses-ipv6 set firewall family inet filter inbound-ipv4 set firewall family inet filter inbound-ipv4 from set firewall family inet filter inbound-ipv4 from destination-prefix-list inside_addresses-ipv4 set firewall family inet filter inbound-ipv4 then accept set firewall family inet6 filter inbound-ipv6 set firewall family inet6 filter inbound-ipv6 from set firewall family inet6 filter inbound-ipv6 from destination-prefix-list inside_addresses-ipv6 set firewall family inet6 filter inbound-ipv6 then accept

Fix Text (F-57392r843999_fix)

This requirement is not applicable for the DODIN Backbone.

Configure the ingress filter of the perimeter router connected to an alternate gateway to only permit packets with destination addresses of the site's NIPRNet address space or a destination address belonging to the address block assigned by the alternate gateway network service provider. For example:

set policy-options prefix-list inside_addresses-ipv4
set policy-options prefix-list inside_addresses-ipv6

set firewall family inet filter inbound-ipv4
set firewall family inet filter inbound-ipv4 from
set firewall family inet filter inbound-ipv4 from destination-prefix-list inside_addresses-ipv4
set firewall family inet filter inbound-ipv4 then accept

set firewall family inet6 filter inbound-ipv6
set firewall family inet6 filter inbound-ipv6 from
set firewall family inet6 filter inbound-ipv6 from destination-prefix-list inside_addresses-ipv6
set firewall family inet6 filter inbound-ipv6 then accept