← Back to VMware vSphere 7.0 vCenter Appliance Photon OS Security Technical Implementation Guide

V-256576

CAT II (Medium)

The Photon operating system must send Transmission Control Protocol (TCP) timestamps.

Rule ID

SV-256576r991589_rule

STIG

VMware vSphere 7.0 vCenter Appliance Photon OS Security Technical Implementation Guide

Version

V1R4

CCIs

CCI-000366

Discussion

TCP timestamps are used to provide protection against wrapped sequence numbers. It is possible to calculate system uptime (and boot time) by analyzing TCP timestamps. These calculated uptimes can help a bad actor in determining likely patch levels for vulnerabilities.

Check Content

At the command line, run the following command:

# /sbin/sysctl -a --pattern "net.ipv4.tcp_timestamps$"

Expected result:

net.ipv4.tcp_timestamps = 1

If the output does not match the expected result, this is a finding.

Fix Text

At the command line, run the following commands:

# sed -i -e "/^net.ipv4.tcp_timestamps/d" /etc/sysctl.conf
# echo net.ipv4.tcp_timestamps=1>>/etc/sysctl.conf
# /sbin/sysctl --load