The Photon operating system must send Transmission Control Protocol (TCP) timestamps.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-256576 | SRG-OS-000480-GPOS-00227 | PHTN-30-000107 | SV-256576r991589_rule | 2024-12-16 | 1 |
Description
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.
ℹ️ Check
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
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