The Juniper perimeter router must be configured to drop IPv6 packets containing a Hop-by-Hop or Destination Option extension header with an undefined option type.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-254059	JUEX-RT-000870	SV-254059r844210_rule		Medium

Description
The optional and extensible natures of the IPv6 extension headers require higher scrutiny since many implementations do not always drop packets with headers that it cannot recognize, and hence could cause a denial-of-service on the target device. In addition, the type, length, value (TLV) formatting provides the ability for headers to be very large.

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

Details

Check Text ( C-57511r844208_chk )
This requirement is not applicable for the DODIN Backbone. Review the router configuration and determine if filters are bound to the applicable interfaces to drop all inbound IPv6 packets containing an undefined option type value regardless of whether they appear in a Hop-by-Hop or Destination Option header. Undefined values are 0x02, 0x03, 0x06, 0x9 – 0xE, 0x10 – 0x22, 0x24, 0x25, 0x27 – 0x2F, and 0x31 – 0xFF. Verify the router drops all hop-by-hop and destination-options extension headers. [edit firewall family inet6] filter { term 1 { from { next-header [ hop-by-hop dstopts ]; } then { log; syslog; discard; } } term default { then { log; syslog; discard; } } } Note: Juniper routers do not support configuring option types for either the Hop-by-Hop or Destination Options extension headers. Therefore, all packets with the Hop-by-Hop or Destination Options extension header are dropped. Verify the filter is applied to applicable interfaces. [edit interfaces] { unit { family inet6 { filter { input ; } 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. The deny-all filter is created once per family and can be reused across multiple lists. For example: input-list [ permit_mgt permit_routing_protocols default-deny ]; If the router is not configured to drop IPv6 packets containing a Hop-by-Hop or Destination Option extension header, this is a finding.

Check Text ( C-57511r844208_chk )

This requirement is not applicable for the DODIN Backbone.

Review the router configuration and determine if filters are bound to the applicable interfaces to drop all inbound IPv6 packets containing an undefined option type value regardless of whether they appear in a Hop-by-Hop or Destination Option header. Undefined values are 0x02, 0x03, 0x06, 0x9 – 0xE, 0x10 – 0x22, 0x24, 0x25, 0x27 – 0x2F, and 0x31 – 0xFF.

Verify the router drops all hop-by-hop and destination-options extension headers.
[edit firewall family inet6]
filter {
term 1 {
from {
next-header [ hop-by-hop dstopts ];
}
then {
log;
syslog;
discard;
}
}

term default {
then {
log;
syslog;
discard;
}
}
}

Note: Juniper routers do not support configuring option types for either the Hop-by-Hop or Destination Options extension headers. Therefore, all packets with the Hop-by-Hop or Destination Options extension header are dropped.

Verify the filter is applied to applicable interfaces.
[edit interfaces]
{
unit {
family inet6 {
filter {
input ;
}
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. The deny-all filter is created once per family and can be reused across multiple lists. For example:

input-list [ permit_mgt permit_routing_protocols default-deny ];

If the router is not configured to drop IPv6 packets containing a Hop-by-Hop or Destination Option extension header, this is a finding.

Fix Text (F-57462r844209_fix)
Configure the router to drop all inbound IPv6 packets containing an undefined option type value regardless of whether or not they appear in a Hop-by-Hop or Destination Option header. set firewall family inet6 filter term 1 from next-header hop-by-hop set firewall family inet6 filter term 1 from next-header dstopts set firewall family inet6 filter term 1 then log set firewall family inet6 filter term 1 then syslog set firewall family inet6 filter term 1 then discard set firewall family inet6 filter term default then log set firewall family inet6 filter term default then syslog set firewall family inet6 filter term default then discard set interfaces unit family inet6 filter input set interfaces unit family inet6 address .

Fix Text (F-57462r844209_fix)

Configure the router to drop all inbound IPv6 packets containing an undefined option type value regardless of whether or not they appear in a Hop-by-Hop or Destination Option header.

set firewall family inet6 filter term 1 from next-header hop-by-hop
set firewall family inet6 filter term 1 from next-header dstopts
set firewall family inet6 filter term 1 then log
set firewall family inet6 filter term 1 then syslog
set firewall family inet6 filter term 1 then discard

set firewall family inet6 filter term default then log
set firewall family inet6 filter term default then syslog
set firewall family inet6 filter term default then discard

set interfaces unit family inet6 filter input
set interfaces unit family inet6 address .