The network element can permit inbound ICMPv6 messages Packet-too-big (type 2), Time Exceeded (type 3), Parameter Problem (type 4), Echo Reply (type 129), and Neighbor Discovery (type 135-136). Remaining ICMPv6 messages must be blocked inbound.

From Perimeter Router Security Technical Implementation Guide Juniper

Part of Inbound ICMPv6 messages are not blocked

SV-40968r1_rule The network element can permit inbound ICMPv6 messages Packet-too-big (type 2), Time Exceeded (type 3), Parameter Problem (type 4), Echo Reply (type 129), and Neighbor Discovery (type 135-136). Remaining ICMPv6 messages must be blocked inbound.

Vulnerability discussion

Scanning will usually be the major stage of an information gathering process a malicious computer attacker will launch against a targeted network. With this stage the malicious computer attacker will try to determine what the characteristics of the targeted network are. Techniques, such as host detection, service detection, network topology mapping, and operating system fingerprinting are often used. The data collected will be used to identify those Hosts (if any) that are running a network service, which may have a known vulnerability. This vulnerability may allow the malicious computer attacker to execute a remote exploit in order to gain unauthorized access to those systems. This unauthorized access may become the focal point to the whole targeted network.

Check content

Review the configuration and ensure only approved ICMP types and codes are permitted into the enclave. Use source and destination filtering where appropriate. Apply the ICMP fragment filter to prevent DOS. [edit firewall] family inet { filter ingress-filter { term block-frags { from { is-fragment; protocol icmp; } then { syslog; discard; } } term icmp-in-good { from { destination-address { 199.36.92.0/30; } protocol icmp; icmp-type [echo-reply source quench time-exceeded parameter problem]; } then { accept; } term icmp-PMTU-D { from { destination-address { 199.36.92.0/24; } protocol icmp; icmp-type [ unreachable ]; icmp-code [ fragmentation-needed ]; } then { accept; } } } term icmp-in-bad { from { protocol icmp; } then { syslog; discard; } } } }

Fix text

The network element must be configured to include controls to block inbound exploitable ICMP traffic message types.

Pro Tips

Lavender hyperlinks in small type off to the right (of CSS class id, if you view the page source) point to globally unique URIs for each document and item. Copy the link location and paste anywhere you need to talk unambiguously about these things.

You can obtain data about documents and items in other formats. Simply provide an HTTP header Accept: text/turtle or Accept: application/rdf+xml.