Menu
The review-first prompt is selected by default. You can switch to a direct command or download a local copy.
Read SKILL.md and any companion files shown by SkillsMP before deciding whether to install.
Based on SOC occupation classification
Install with Codex or Claude Copy this prompt, paste it into Codex, Claude, or another assistant, and let it review the skill page and install it for you.
A direct command skips the review prompt. Inspect the source before running it.
npx skills add https://github.com/CyberStrikeus/CyberStrike --skill cis-ubuntu2004-v300-4-2-5The command stays on one line. Scroll horizontally to inspect it before copying.
Prefer a local copy? Download the files currently available to SkillsMP.
Showing SKILL.md
macOS post-exploitation for credential harvesting, DTrace monitoring, TCC bypass, and stealth operations via native tools
Windows userland post-exploitation for credential harvesting, monitoring, AMSI/ETW bypass, and stealth operations
Kubernetes post-exploitation for container escape, secret extraction, RBAC abuse, and cluster persistence
| name | cis-ubuntu2004-v300-4-2-5 |
| description | Ensure ufw loopback traffic is configured |
| category | cis-networking |
| version | 3.0.0 |
| author | cyberstrike-official |
| tags | ["cis","ubuntu","linux","ubuntu-20.04","firewall","ufw"] |
| cis_id | 4.2.5 |
| cis_benchmark | CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0 |
| tech_stack | ["ubuntu","linux"] |
| cwe_ids | [] |
| chains_with | [] |
| prerequisites | [] |
| severity_boost | {} |
Configure the loopback interface to accept traffic. Configure all other interfaces to deny traffic to the loopback network (127.0.0.0/8 for IPv4 and ::1/128 for IPv6).
Loopback traffic is generated between processes on machine and is typically critical to operation of the system. The loopback interface is the only place that loopback network (127.0.0.0/8 for IPv4 and ::1/128 for IPv6) traffic should be seen, all other interfaces should ignore traffic on this network as an anti-spoofing measure.
Run the following command and verify loopback interface to accept traffic:
grep -P -- 'lo|127.0.0.0' /etc/ufw/before.rules
Output includes:
# allow all on loopback
-A ufw-before-input -i lo -j ACCEPT
-A ufw-before-output -o lo -j ACCEPT
Run the following command and verify all other interfaces deny traffic to the loopback network (127.0.0.0/8 for IPv4 and ::1/128 for IPv6):
ufw status verbose
To Action From
-- ------ ----
Anywhere DENY IN 127.0.0.0/8
Anywhere (v6) DENY IN ::1
Note: ufw status only shows rules added with ufw and not the rules found in the /etc/ufw rules files where allow all on loopback is configured by default.
Loopback accept rules present in before.rules and deny rules for 127.0.0.0/8 and ::1 in ufw status.
Run the following commands to configure the loopback interface to accept traffic:
ufw allow in on lo
ufw allow out on lo
Run the following commands to configure all other interfaces to deny traffic to the loopback network:
ufw deny in from 127.0.0.0/8
ufw deny in from ::1
# allow all on loopback
-A ufw-before-input -i lo -j ACCEPT
-A ufw-before-output -o lo -j ACCEPT
v8 - 4.4 Implement and Manage a Firewall on Servers v8 - 4.5 Implement and Manage a Firewall on End-User Devices v7 - 9.4 Apply Host-based Firewalls or Port Filtering
MITRE ATT&CK Mappings: T1562, T1562.004 | TA0011 | M1031, M1037