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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-gcp-cos-3.3.2.2 |
| description | Ensure loopback traffic is configured |
| category | cis-gcp-cos |
| version | 1.2.0 |
| author | cyberstrike-official |
| tags | ["cis","gcp","container-optimized-os","firewall","iptables","ipv4","network-security","loopback"] |
| cis_id | 3.3.2.2 |
| cis_benchmark | CIS Google Container-Optimized OS Benchmark v1.2.0 |
| tech_stack | ["gcp","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).
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) traffic should be seen, all other interfaces should ignore traffic on this network as an anti-spoofing measure.
Changing firewall settings while connected over network can result in being locked out of the system.
Remediation will only affect the active system firewall, be sure to configure the default policy in your firewall management to apply on boot as well.
Run the following commands and verify output includes the listed rules in order (packet and byte counts may differ):
iptables -L INPUT -v -n
Chain INPUT (policy DROP 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
0 0 DROP all -- * * 127.0.0.0/8 0.0.0.0/0
iptables -L OUTPUT -v -n
Chain OUTPUT (policy DROP 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 ACCEPT all -- * lo 0.0.0.0/0 0.0.0.0/0
lo)127.0.0.0/8lo)Run the following commands to implement the loopback rules:
iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT
iptables -A INPUT -s 127.0.0.0/8 -j DROP
| Controls Version | Control | IG 1 | IG 2 | IG 3 |
|---|---|---|---|---|
| v8 | 4.4 Implement and Manage a Firewall on Servers - Implement and manage a firewall on servers, where supported. Example implementations include a virtual firewall, operating system firewall, or a third-party firewall agent. | x |
Based on SOC occupation classification
| x |
| x |
| v7 | 9.4 Apply Host-based Firewalls or Port Filtering - Apply host-based firewalls or port filtering tools on end systems, with a default-deny rule that drops all traffic except those services and ports that are explicitly allowed. | x | x | x |
