Title

The system must not respond to ICMPv4 echoes sent to a broadcast address. (Cat II impact)

Discussion

Responding to broadcast Internet Control Message Protocol (ICMP) echoes facilitates network mapping and provides a vector for amplification attacks.

Check Content

Determine the type of zone that you are currently securing. # zonename If the zone is not the global zone, determine if any interfaces are exclusive to the zone: # dladm show-link If the output indicates "insufficient privileges" then this requirement is not applicable. If the zone is the global zone or the non-global zone has exclusive interfaces verify the system does not respond to ICMP ECHO_REQUESTs set to broadcast addresses. # ndd /dev/ip ip_respond_to_echo_broadcast If the result is not 0, this is a finding.

Fix Text

Configure the system to not respond to ICMP ECHO_REQUESTs sent to broadcast addresses. # ndd -set /dev/ip ip_respond_to_echo_broadcast 0 Also add this command to a system startup script.

Additional Identifiers

Rule ID: SV-227796r603266_rule

Vulnerability ID: V-227796

Group Title: SRG-OS-000480

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.