The network device must be configured to ensure IPv6 Site Local Unicast addresses are not defined in the enclave, (FEC0::/10). Note that this consist of all addresses that begin with FEC, FED, FEE and FEF.

From Infrastructure L3 Switch Secure Technical Implementation Guide - Cisco

Part of IPv6 Site Local Unicast ADDR must not be defined

Associated with IA controls: ECSC-1

SV-15397r2_rule The network device must be configured to ensure IPv6 Site Local Unicast addresses are not defined in the enclave, (FEC0::/10). Note that this consist of all addresses that begin with FEC, FED, FEE and FEF.

Vulnerability discussion

As currently defined, site local addresses are ambiguous and can be present in multiple sites. The address itself does not contain any indication of the site to which it belongs. The use of site-local addresses has the potential to adversely affect network security through leaks, ambiguity and potential misrouting, as documented in section 2 of RFC3879. RFC3879 formally deprecates the IPv6 site-local unicast prefix defined in RFC3513, i.e., 1111111011 binary or FEC0::/10.

Check content

Review the device configuration to ensure FEC0::/10 IP addresses are not defined. If FEC0::/10 IP addresses are defined, this is a finding.

Fix text

Configure the device using authorized IP addresses.

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