TMA-COS-5.1.20

Ensure SSH AllowTcpForwarding is disabled

BajaNivel 2Automatizadacos

Descripción

SSH port forwarding is a mechanism in SSH for tunneling application ports from the client to the server, or servers to clients. It can be used for adding encryption to legacy applications, going through firewalls, and some system administrators and IT professionals use it for opening backdoors into the internal network from their home machines Leaving port forwarding enabled can expose the organization to security risks and back- doors. SSH connections are protected with strong encryption. This makes their contents invisible to most deployed network monitoring and traffic filtering solutions. This invisibility carries considerable risk potential if it is used for malicious purposes such as data exfiltration. Cybercriminals or malware could exploit SSH to hide their unauthorized communications, or to exfiltrate stolen data from the target network

Cómo se verifica

Método de auditoría: Comando de shell

shell

alt0() { command -v grep >/dev/null 2>&1 || { echo "step1: grep not installed"; return 1; }; command -v sshd >/dev/null 2>&1 || { echo "step1: sshd not installed"; return 1; }; o=$(bash -c 'sshd -T | grep -i allowtcpforwarding' 2>&1); printf '%s\n' "$o" | tr -s ' \t' '  ' | sed 's/^ //;s/ $//' | grep -Fxq -- 'AllowTcpForwarding no' || { echo step1: missing 'AllowTcpForwarding no'; return 1; }; }; if alt0; then echo compliant; fi

Salida esperada: compliant

Cómo se corrige

Método de corrección: Guía o parche de infraestructura

Edit the /etc/ssh/sshd_config file to set the parameter as follows: AllowTcpForwarding no

Propiedades

Sistemas operativos: Cualquiera
Etiquetas: container-optimized-oscosssh
Referencia: CIS Google Container-Optimized OS Benchmark v1.2.0 - 5.1.20 Ensure SSH AllowTcpForwarding is disabled

Verificar este host

Ejecute esto en un equipo que tenga permiso para auditar. El escaneo es de solo lectura.

shell

tmaegis scan --target cos --level 2