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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-91559	AIX7-00-003097	SV-101657r1_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 AIX 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 AIX 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
IBM AIX 7.x Security Technical Implementation Guide	2020-02-24

Details

Check Text ( C-90713r5_chk )
Check to see if bos.net.tcp.client_core package is installed: # lslpp -l \| grep bos.net.tcp.client_core bos.net.tcp.client_core 7.2.1.1 COMMITTED TCP/IP Client Core Support bos.net.tcp.client_core 7.2.1.1 COMMITTED TCP/IP Client Core Support If the packages are not "COMMITTED", this is a finding. Check that the value set for "clean_partial_conns" is "1": # /usr/sbin/no -o clean_partial_conns clean_partial_conns = 1 If the value returned is "0", this is a finding.

Check Text ( C-90713r5_chk )

Check to see if bos.net.tcp.client_core package is installed:

# lslpp -l | grep bos.net.tcp.client_core
bos.net.tcp.client_core 7.2.1.1 COMMITTED TCP/IP Client Core Support
bos.net.tcp.client_core 7.2.1.1 COMMITTED TCP/IP Client Core Support

If the packages are not "COMMITTED", this is a finding.

Check that the value set for "clean_partial_conns" is "1":

# /usr/sbin/no -o clean_partial_conns
clean_partial_conns = 1

If the value returned is "0", this is a finding.

Fix Text (F-97757r1_fix)
Make sure "bos.net.tcp.client_core" package is installed on the system. Set the Network performance tuning attribute value for "clean_partial_connections to "1" to avoid SYN attacks. # /usr/sbin/no -o clean_partial_conns=1