Title

A firewall must be able to protect against or limit the effects of Denial of Service (DoS) attacks by ensuring TOSS can implement rate-limiting measures on impacted network interfaces. (Cat II impact)

Discussion

DoS is a condition when a resource is not available for legitimate users. When this occurs, the organization either cannot accomplish its mission or must operate at degraded capacity. This requirement addresses the configuration of TOSS to mitigate the impact of DoS attacks that have occurred or are ongoing on system availability. For each system, known and potential DoS attacks must be identified and solutions for each type implemented. A variety of technologies exists to limit or, in some cases, eliminate the effects of DoS attacks (e.g., limiting processes or establishing memory partitions). Employing increased capacity and bandwidth, combined with service redundancy, may reduce the susceptibility to some DoS attacks. Since version 0.6.0, "firewalld" has incorporated "nftables" as its backend support. Utilizing the limit statement in "nftables" can help to mitigate DoS attacks.

Check Content

Verify "firewalld" has "nftables" set as the default backend: $ sudo grep -i firewallbackend /etc/firewalld/firewalld.conf # FirewallBackend FirewallBackend=nftables If the "nftables" is not set as the "firewallbackend" default, this is a finding.

Fix Text

Configure "nftables" to be the default "firewallbackend" for "firewalld" by adding or editing the following line in "/etc/firewalld/firewalld.conf": FirewallBackend=nftables Establish rate-limiting rules based on organization-defined types of DoS attacks on impacted network interfaces.

Additional Identifiers

Rule ID: SV-253092r958902_rule

Vulnerability ID: V-253092

Group Title: SRG-OS-000420-GPOS-00186

Expert Comments

CCIs tied to check.

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