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The system must not process Internet Control Message Protocol (ICMP) timestamp requests.


Overview

Finding ID Version Rule ID IA Controls Severity
V-22409 GEN003602 SV-37601r1_rule ECSC-1 Low
Description
The processing of (ICMP) timestamp requests increases the attack surface of the system.
STIG Date
Red Hat Enterprise Linux 5 Security Technical Implementation Guide 2014-01-09

Details

Check Text ( C-36721r2_chk )
Verify the system does not respond to ICMP TIMESTAMP_REQUESTs

Procedure:
# grep "timestamp" /etc/sysconfig/iptables

This should return entries for "timestamp-reply" and "timestamp_request". Both should end with "-j DROP'. If either does not exist or does not "DROP" the message, this is a finding.
Fix Text (F-31637r1_fix)
Configure the system to not respond to ICMP TIMESTAMP_REQUESTs. This is done by rejecting ICMP type 13 and 14 messages at the firewall.

Procedure:
Edit /etc/sysconfig/iptables to add:

-A RH-Firewall-1-INPUT -p ICMP --icmp-type timestamp-request -j DROP
-A RH-Firewall-1-INPUT -p ICMP --icmp-type timestamp-reply -j DROP

Restart the firewall:
# service iptables restart