The operating system must protect against or limit the effects of Denial of Service (DoS) attacks by validating the operating system is implementing rate-limiting measures on impacted network interfaces.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-72271	RHEL-07-040510	SV-86895r2_rule		Medium

Description
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 the operating system 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 exist 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.

Description

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 the operating system 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 exist 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.

STIG	Date
Red Hat Enterprise Linux 7 Security Technical Implementation Guide	2017-07-08

Details

Check Text ( C-72505r1_chk )
Verify the operating system protects against or limits the effects of DoS attacks by ensuring the operating system is implementing rate-limiting measures on impacted network interfaces. Check the firewall configuration with the following command: Note: The command is to query rules for the public zone. # firewall-cmd --direct --get-rule ipv4 filter IN_public_allow rule ipv4 filter IN_public_allow 0 -p tcp -m limit --limit 25/minute --limit-burst 100 -j ACCEPT If a rule with both the limit and limit-burst arguments parameters does not exist, this is a finding.

Check Text ( C-72505r1_chk )

Verify the operating system protects against or limits the effects of DoS attacks by ensuring the operating system is implementing rate-limiting measures on impacted network interfaces.

Check the firewall configuration with the following command:

Note: The command is to query rules for the public zone.

# firewall-cmd --direct --get-rule ipv4 filter IN_public_allow
rule ipv4 filter IN_public_allow 0 -p tcp -m limit --limit 25/minute --limit-burst 100 -j ACCEPT

If a rule with both the limit and limit-burst arguments parameters does not exist, this is a finding.

Fix Text (F-78625r2_fix)
Create a direct firewall rule to protect against DoS attacks with the following command: Note: The command is to add a rule to the public zone. # firewall-cmd --direct --permanent --add-rule ipv4 filter IN_public_allow 0 -m tcp -p tcp -m limit --limit 25/minute --limit-burst 100 -j ACCEPT The firewalld service will need to be restarted for this to take effect: # systemctl restart firewalld