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Check: SRG-NET-000205-RTR-000008

Router SRG: SRG-NET-000205-RTR-000008 (in versions v5 r1 through v4 r1)

Title

The PE router must be configured with Unicast Reverse Path Forwarding (uRPF) loose mode enabled on all CE-facing interfaces.. (Cat II impact)

Discussion

The uRPF feature is a defense against spoofing and denial-of-service (DoS) attacks by verifying if the source address of any ingress packet is reachable. To mitigate attacks that rely on forged source addresses, all provider edge routers must enable uRPF loose mode to guarantee that all packets received from a CE router contain source addresses that are in the route table.

Check Content

Review the router configuration to determine if uRPF loose mode is enabled on all CE-facing interfaces. If uRPF loose mode is not enabled on all CE-facing interfaces, this is a finding.

Fix Text

Enable uRPF loose mode on all CE-facing interfaces.

Additional Identifiers

Rule ID: SV-207140r604135_rule

Vulnerability ID: V-207140

Group Title: SRG-NET-000205

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CCIs

CCIs tied to check.

Number	Definition
CCI-001097	Monitor and control communications at the external managed interfaces to the system and at key managed interfaces within the system.

Controls

Controls tied to check. These are derived from the CCIs shown above.

Number	Title
SC-7	Boundary Protection