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-29288r1_rule	ECSC-1	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
Red Hat Enterprise Linux 5 Security Technical Implementation Guide	2014-07-02

Details

Check Text ( None )
None

Fix Text (F-31645r1_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