The network element can permit outbound ICMPv6 messages Packet-too-big (type 2), Echo Request (type 128), and Neighborhood Discovery (type 135-136). Remaining ICMPv6 messages must be blocked outbound.

From Perimeter Router Security Technical Implementation Guide Juniper

Part of Outbound ICMPv6 traffic is not blocked

SV-15375r2_rule The network element can permit outbound ICMPv6 messages Packet-too-big (type 2), Echo Request (type 128), and Neighborhood Discovery (type 135-136). Remaining ICMPv6 messages must be blocked outbound.

Vulnerability discussion

Scanning will usually be the major stage of an information gathering process a malicious computer attacker will lunch 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 are permitted to exit the enclave. Junos example [edit interfaces] fe-2/0/10 { description "link to our network”; unit 0 { family inet6 { filter { input egress-filter; } address 2001:db8:60::f15:60c2; } } } } [edit firewall] family inet6 { filter egress-filter { term icmp-out-good { from { source-address { 2001:db8:60::f15:60c2; } protocol icmp; icmp-type [ echo-request packet-too-big]; } then { accept; } } term icmp-out-bad { from { protocol icmp; } then { syslog; discard; } } } }

Fix text

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

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