The system must not respond to Internet Control Message Protocol (ICMP) timestamp requests sent to a broadcast address.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-22411	GEN003604	SV-45723r1_rule		Medium

Description
The processing of (ICMP) timestamp requests increases the attack surface of the system. Responding to broadcast ICMP timestamp requests facilitates network mapping and provides a vector for amplification attacks.

STIG	Date
SUSE Linux Enterprise Server v11 for System z Security Technical Implementation Guide	2018-09-19

Details

Check Text ( C-43090r1_chk )
Verify the system does not respond to ICMP TIMESTAMP_REQUESTs set to broadcast addresses. Procedure: # cat /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts If the result is not 1, this is a finding. Note: The same parameter controls both ICMP ECHO_REQUESTs and TIMESTAMP_REQUESTs.

Fix Text (F-39121r1_fix)
Configure the system to not respond to ICMP TIMESTAMP_REQUESTs sent to broadcast addresses. Edit /etc/sysctl.conf and add a setting for "net.ipv4.icmp_echo_ignore_broadcasts=1" and reload the sysctls. Procedure: # echo "net.ipv4.icmp_echo_ignore_broadcasts=1" >> /etc/sysctl.conf # sysctl -p