CVE-2021-0277

Solution:

• The following software releases have been updated to resolve this specific issue: Junos OS 12.3R12-S18, 15.1R7-S9, 17.3R3-S12, 17.4R2-S13, 17.4R3-S5, 18.1R3-S13, 18.2R3-S8, 18.3R3-S5, 18.4R2-S8, 18.4R3-S8, 19.1R3-S5, 19.3R2-S6, 19.3R3-S2, 19.4R1-S4, 19.4R2-S4, 19.4R3-S3, 20.1R2-S2, 20.1R3, 20.2R3-S1, 20.3R2-S1, 20.3R3, 20.4R2, 20.4R3, 21.1R1, 21.1R2, 21.2R1, and all subsequent releases. Junos OS Evolved 20.4R2-EVO, 21.1R1-EVO, and all subsequent releases.

Workaround:

• 1. Configure the device to not load the L2CPD daemon using the following CLI config stanza. set system processes l2cpd-service disable Additional protocols L2CPD daemon supports include RSTP, MSTP, VSTP, ERP, xSTP and ERP protocols. After issuing set system processes l2cpd-service disable, RSTP, MSTP, VSTP, ERP, xSTP and ERP protocols will cease to operate. Please note, this is not an exhaustive list, disabling L2CPD may affect other protocols and services that rely upon L2CPD daemon to be present. For example, L2ALD, MRVP, EVPN traffic, etc. may also cease to operate. To avoid downtime, customers considering applying this workaround should carefully test all workaround changes to their environment in a non-production environment first that mirrors or as closely as possible matches the production environment before applying to the production environment. 2. Configure target interfaces on the device to disable LLDP packet processing: set protocols lldp interface disable 3. On Switching platforms such as EX/QFX Series devices implement packet filters to discard LLDP packets with an EtherType of 0x88cc. For example: set firewall family ethernet-switching filter LLDP_EXAMPLE term 1 from ether-type 0x88cc set firewall family ethernet-switching filter LLDP_EXAMPLE term 1 then discard Workaround #3 does not work on MX Series devices. MX Series devices should disable LLDP processing, filter off-system, or upgrade to a fixed release. 4. Lastly, as a method to reduce the risk of exploitation for this vulnerability, customers may implement off-system IDP and/or Firewall filtering methods such as disallowing LLDP EtherType to propagate completely on local segments, or by filtering broadcast addressed LLDP packets or unicast addressed LLDP packets not originated from trusted sources targeted to trusted destinations. Additionally, it is good security practice to limit the exploitable attack surface of critical infrastructure networking equipment. Use access lists or firewall filters to limit access to the device via all means to only trusted, administrative networks, hosts and users.