Rule ID
SV-240517r852578_rule
Version
V2R2
CCIs
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.
Check that the system configured to use TCP syncookies when experiencing a TCP SYN flood. # cat /proc/sys/net/ipv4/tcp_syncookies If the result is not "1", this is a finding.
Configure the system to use TCP syncookies when experiencing a TCP SYN flood. Check for the presence of "net.ipv4.tcp_syncookies" in the /etc/sysctl.conf file: # grep "net.ipv4.tcp_syncookies" /etc/sysctl.conf If it exists, change the value to "1". If it does not exist, add a setting for tcp_syncookies: # echo "net.ipv4.tcp_syncookies=1" >> /etc/sysctl.conf Reload sysctl to verify the new change: # sysctl -p