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.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-215399	SRG-OS-000420-GPOS-00186	AIX7-00-003097	SV-215399r958902_rule	2024-08-16	3

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.

ℹ️ Check
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.

ℹ️ Check

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
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