The Cisco PE router must be configured to enforce a Quality-of-Service (QoS) policy to limit the effects of packet flooding denial-of-service (DoS) attacks.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-216806	CISC-RT-000780	SV-216806r531087_rule		Medium

Description
DoS is a condition when a resource is not available for legitimate users. Packet flooding distributed denial-of-service (DDoS) attacks are referred to as volumetric attacks and have the objective of overloading a network or circuit to deny or seriously degrade performance, which denies access to the services that normally traverse the network or circuit. Volumetric attacks have become relatively easy to launch using readily available tools such as Low Orbit Ion Cannon or botnets. Measures to mitigate the effects of a successful volumetric attack must be taken to ensure that sufficient capacity is available for mission-critical traffic. Managing capacity may include, for example, establishing selected network usage priorities or quotas and enforcing them using rate limiting, Quality of Service (QoS), or other resource reservation control methods. These measures may also mitigate the effects of sudden decreases in network capacity that are the result of accidental or intentional physical damage to telecommunications facilities (such as cable cuts or weather-related outages).

Description

DoS is a condition when a resource is not available for legitimate users. Packet flooding distributed denial-of-service (DDoS) attacks are referred to as volumetric attacks and have the objective of overloading a network or circuit to deny or seriously degrade performance, which denies access to the services that normally traverse the network or circuit. Volumetric attacks have become relatively easy to launch using readily available tools such as Low Orbit Ion Cannon or botnets. Measures to mitigate the effects of a successful volumetric attack must be taken to ensure that sufficient capacity is available for mission-critical traffic. Managing capacity may include, for example, establishing selected network usage priorities or quotas and enforcing them using rate limiting, Quality of Service (QoS), or other resource reservation control methods. These measures may also mitigate the effects of sudden decreases in network capacity that are the result of accidental or intentional physical damage to telecommunications facilities (such as cable cuts or weather-related outages).

STIG	Date
Cisco IOS XR Router RTR Security Technical Implementation Guide	2024-06-06

Details

Check Text ( C-18038r288792_chk )
Step 1: Verify that a class map has been configured for the Scavenger class as shown in the example below. class-map match-all SCAVENGER match dscp cs1 end-class-map Step 2: Verify that the policy map includes the SCAVENGER class with low priority as shown in the following example below. policy-map QOS_POLICY class C2_VOICE bandwidth percent 10 ! class VOICE bandwidth percent 15 ! class VIDEO bandwidth percent 25 ! class CONTROL_PLANE bandwidth percent 10 ! class PREFERRED_DATA bandwidth percent 25 ! class SCAVENGER bandwidth percent 5 ! class class-default bandwidth percent 10 ! end-policy-map Note: Traffic out of profile must be marked at the customer access layer or CE egress edge. If the policy map does not include the SCAVENGER class with low priority, this is a finding.

Check Text ( C-18038r288792_chk )

Step 1: Verify that a class map has been configured for the Scavenger class as shown in the example below.

class-map match-all SCAVENGER
match dscp cs1
end-class-map

Step 2: Verify that the policy map includes the SCAVENGER class with low priority as shown in the following example below.

policy-map QOS_POLICY
class C2_VOICE
bandwidth percent 10
!
class VOICE
bandwidth percent 15
!
class VIDEO
bandwidth percent 25
!
class CONTROL_PLANE
bandwidth percent 10
!
class PREFERRED_DATA
bandwidth percent 25
!
class SCAVENGER
bandwidth percent 5
!
class class-default
bandwidth percent 10
!
end-policy-map

Note: Traffic out of profile must be marked at the customer access layer or CE egress edge.

If the policy map does not include the SCAVENGER class with low priority, this is a finding.

Fix Text (F-18036r288793_fix)
Step 1: Configure a class map for the SCAVENGER class. RP/0/0/CPU0:R2(config)#class-map match-all SCAVENGER RP/0/0/CPU0:R2(config-cmap)#match dscp cs1 RP/0/0/CPU0:R2(config-cmap)#exit Step 2: Add the SCAVENGER class to the policy map as shown in the example below. RP/0/0/CPU0:R2(config)#policy-map QOS_POLICY RP/0/0/CPU0:R2(config-pmap)#no class class-default RP/0/0/CPU0:R2(config-pmap)#class SCAVENGER RP/0/0/CPU0:R2(config-pmap-c)#bandwidth percent 5 RP/0/0/CPU0:R2(config-pmap-c)#class class-default RP/0/0/CPU0:R2(config-pmap-c)#bandwidth percent 10 RP/0/0/CPU0:R2(config-pmap-c)#end

Fix Text (F-18036r288793_fix)

Step 1: Configure a class map for the SCAVENGER class.

RP/0/0/CPU0:R2(config)#class-map match-all SCAVENGER
RP/0/0/CPU0:R2(config-cmap)#match dscp cs1
RP/0/0/CPU0:R2(config-cmap)#exit

Step 2: Add the SCAVENGER class to the policy map as shown in the example below.

RP/0/0/CPU0:R2(config)#policy-map QOS_POLICY
RP/0/0/CPU0:R2(config-pmap)#no class class-default
RP/0/0/CPU0:R2(config-pmap)#class SCAVENGER
RP/0/0/CPU0:R2(config-pmap-c)#bandwidth percent 5
RP/0/0/CPU0:R2(config-pmap-c)#class class-default
RP/0/0/CPU0:R2(config-pmap-c)#bandwidth percent 10
RP/0/0/CPU0:R2(config-pmap-c)#end