Clear-text protocols such as ftp, telnet, or http lack encryption of transported data, as well as the capability to build an authenticated connection. It means that an attacker able to sniff traffic from the network can read, modify, or corrupt the transported content. These protocols are not secure as they expose applications to an extensive range of risks:

Even in the context of isolated networks like offline environments or segmented cloud environments, the insider threat exists. Thus, attacks involving communications being sniffed or tampered with can still happen.

For example, attackers could successfully compromise prior security layers by:

In such cases, encrypting communications would decrease the chances of attackers to successfully leak data or steal credentials from other network components. By layering various security practices (segmentation and encryption, for example), the application will follow the defense-in-depth principle.

Note that using the http protocol is being deprecated by major web browsers.

In the past, it has led to the following vulnerabilities:

Ask Yourself Whether

There is a risk if you answered yes to any of those questions.

Recommended Secure Coding Practices

It is recommended to secure all transport channels, even on local networks, as it can take a single non-secure connection to compromise an entire application or system.

Sensitive Code Example

url = "http://example.com"; // Sensitive
url = "ftp://anonymous@example.com"; // Sensitive
url = "telnet://anonymous@example.com"; // Sensitive

For nodemailer:

const nodemailer = require("nodemailer");
let transporter = nodemailer.createTransport({
  secure: false, // Sensitive
  requireTLS: false // Sensitive
});

const nodemailer = require("nodemailer");
let transporter = nodemailer.createTransport({}); // Sensitive

For ftp:

var Client = require('ftp');
var c = new Client();
c.connect({
  'secure': false // Sensitive
});

For telnet-client:

const Telnet = require('telnet-client'); // Sensitive

For aws-cdk-lib.aws-elasticloadbalancingv2.ApplicationLoadBalancer:

import { ApplicationLoadBalancer } from 'aws-cdk-lib/aws-elasticloadbalancingv2';

const alb = new ApplicationLoadBalancer(this, 'ALB', {
  vpc: vpc,
  internetFacing: true
});

alb.addListener('listener-http-default', {
  port: 8080,
  open: true
}); // Sensitive

alb.addListener('listener-http-explicit', {
  protocol: ApplicationProtocol.HTTP, // Sensitive
  port: 8080,
  open: true
});

For aws-cdk-lib.aws-elasticloadbalancingv2.ApplicationListener:

import { ApplicationListener } from 'aws-cdk-lib/aws-elasticloadbalancingv2';

new ApplicationListener(this, 'listener-http-explicit-constructor', {
  loadBalancer: alb,
  protocol: ApplicationProtocol.HTTP, // Sensitive
  port: 8080,
  open: true
});

For aws-cdk-lib.aws-elasticloadbalancingv2.NetworkLoadBalancer:

import { NetworkLoadBalancer } from 'aws-cdk-lib/aws-elasticloadbalancingv2';

const nlb = new NetworkLoadBalancer(this, 'nlb', {
  vpc: vpc,
  internetFacing: true
});

var listenerNLB = nlb.addListener('listener-tcp-default', {
  port: 1234
}); // Sensitive

listenerNLB = nlb.addListener('listener-tcp-explicit', {
  protocol: Protocol.TCP, // Sensitive
  port: 1234
});

For aws-cdk-lib.aws-elasticloadbalancingv2.NetworkListener:

import { NetworkListener } from 'aws-cdk-lib/aws-elasticloadbalancingv2';

new NetworkListener(this, 'listener-tcp-explicit-constructor', {
  loadBalancer: nlb,
  protocol: Protocol.TCP, // Sensitive
  port: 8080
});

For aws-cdk-lib.aws-elasticloadbalancingv2.CfnListener:

import { CfnListener } from 'aws-cdk-lib/aws-elasticloadbalancingv2';

new CfnListener(this, 'listener-http', {
  defaultActions: defaultActions,
  loadBalancerArn: alb.loadBalancerArn,
  protocol: "HTTP", // Sensitive
  port: 80
});

new CfnListener(this, 'listener-tcp', {
  defaultActions: defaultActions,
  loadBalancerArn: alb.loadBalancerArn,
  protocol: "TCP", // Sensitive
  port: 80
});

For aws-cdk-lib.aws-elasticloadbalancing.CfnLoadBalancer:

import { CfnLoadBalancer } from 'aws-cdk-lib/aws-elasticloadbalancing';

new CfnLoadBalancer(this, 'elb-tcp', {
  listeners: [{
    instancePort: '1000',
    loadBalancerPort: '1000',
    protocol: 'tcp' // Sensitive
  }]
});

new CfnLoadBalancer(this, 'elb-http', {
  listeners: [{
    instancePort: '1000',
    loadBalancerPort: '1000',
    protocol: 'http' // Sensitive
  }]
});

For aws-cdk-lib.aws-elasticloadbalancing.LoadBalancer:

import { LoadBalancer } from 'aws-cdk-lib/aws-elasticloadbalancing';

const loadBalancer = new LoadBalancer(this, 'elb-tcp-dict', {
    vpc,
    internetFacing: true,
    healthCheck: {
    port: 80,
    },
    listeners: [
    {
        externalPort:10000,
        externalProtocol: LoadBalancingProtocol.TCP, // Sensitive
        internalPort:10000
    }]
});

loadBalancer.addListener({
  externalPort:10001,
  externalProtocol:LoadBalancingProtocol.TCP, // Sensitive
  internalPort:10001
});
loadBalancer.addListener({
  externalPort:10002,
  externalProtocol:LoadBalancingProtocol.HTTP, // Sensitive
  internalPort:10002
});

For aws-cdk-lib.aws-elasticache.CfnReplicationGroup:

import { CfnReplicationGroup } from 'aws-cdk-lib/aws-elasticache';

new CfnReplicationGroup(this, 'unencrypted-implicit', {
  replicationGroupDescription: 'exampleDescription'
}); // Sensitive

new CfnReplicationGroup(this, 'unencrypted-explicit', {
  replicationGroupDescription: 'exampleDescription',
  transitEncryptionEnabled: false // Sensitive
});

For aws-cdk-lib.aws-kinesis.CfnStream:

import { CfnStream } from 'aws-cdk-lib/aws-kinesis';

new CfnStream(this, 'cfnstream-implicit-unencrytped', undefined); // Sensitive

new CfnStream(this, 'cfnstream-explicit-unencrytped', {
  streamEncryption: undefined // Sensitive
});

For aws-cdk-lib.aws-kinesis.Stream:

import { Stream } from 'aws-cdk-lib/aws-kinesis';

new Stream(this, 'stream-explicit-unencrypted', {
  encryption: StreamEncryption.UNENCRYPTED // Sensitive
});

Compliant Solution

url = "https://example.com";
url = "sftp://anonymous@example.com";
url = "ssh://anonymous@example.com";

For nodemailer one of the following options must be set:

const nodemailer = require("nodemailer");
let transporter = nodemailer.createTransport({
  secure: true,
  requireTLS: true,
  port: 465,
  secured: true
});

For ftp:

var Client = require('ftp');
var c = new Client();
c.connect({
  'secure': true
});

For aws-cdk-lib.aws-elasticloadbalancingv2.ApplicationLoadBalancer:

import { ApplicationLoadBalancer } from 'aws-cdk-lib/aws-elasticloadbalancingv2';

const alb = new ApplicationLoadBalancer(this, 'ALB', {
  vpc: vpc,
  internetFacing: true
});

alb.addListener('listener-https-explicit', {
  protocol: ApplicationProtocol.HTTPS,
  port: 8080,
  open: true,
  certificates: [certificate]
});

alb.addListener('listener-https-implicit', {
  port: 8080,
  open: true,
  certificates: [certificate]
});

For aws-cdk-lib.aws-elasticloadbalancingv2.ApplicationListener:

import { ApplicationListener } from 'aws-cdk-lib/aws-elasticloadbalancingv2';

new ApplicationListener(this, 'listener-https-explicit', {
  loadBalancer: loadBalancer,
  protocol: ApplicationProtocol.HTTPS,
  port: 8080,
  open: true,
  certificates: [certificate]
});

For aws-cdk-lib.aws-elasticloadbalancingv2.NetworkLoadBalancer:

import { NetworkLoadBalancer } from 'aws-cdk-lib/aws-elasticloadbalancingv2';

const nlb = new NetworkLoadBalancer(this, 'nlb', {
  vpc: vpc,
  internetFacing: true
});

nlb.addListener('listener-tls-explicit', {
  protocol: Protocol.TLS,
  port: 1234,
  certificates: [certificate]
});

nlb.addListener('listener-tls-implicit', {
  port: 1234,
  certificates: [certificate]
});

For aws-cdk-lib.aws-elasticloadbalancingv2.NetworkListener:

import { NetworkListener } from 'aws-cdk-lib/aws-elasticloadbalancingv2';

new NetworkListener(this, 'listener-tls-explicit', {
  loadBalancer: loadBalancer,
  protocol: Protocol.TLS,
  port: 8080,
  certificates: [certificate]
});

For aws-cdk-lib.aws-elasticloadbalancingv2.CfnListener:

import { CfnListener } from 'aws-cdk-lib/aws-elasticloadbalancingv2';

new CfnListener(this, 'listener-https', {
  defaultActions: defaultActions,
  loadBalancerArn: loadBalancerArn,
  protocol: "HTTPS",
  port: 80
  certificates: [certificate]
});

new CfnListener(this, 'listener-tls', {
  defaultActions: defaultActions,
  loadBalancerArn: loadBalancerArn,
  protocol: "TLS",
  port: 80
  certificates: [certificate]
});

For aws-cdk-lib.aws-elasticloadbalancing.CfnLoadBalancer:

import { CfnLoadBalancer } from 'aws-cdk-lib/aws-elasticloadbalancing';

new CfnLoadBalancer(this, 'elb-ssl', {
  listeners: [{
    instancePort: '1000',
    loadBalancerPort: '1000',
    protocol: 'ssl',
    sslCertificateId: sslCertificateId
  }]
});

new CfnLoadBalancer(this, 'elb-https', {
  listeners: [{
    instancePort: '1000',
    loadBalancerPort: '1000',
    protocol: 'https',
    sslCertificateId: sslCertificateId
  }]
});

For aws-cdk-lib.aws-elasticloadbalancing.LoadBalancer:

import { LoadBalancer, LoadBalancingProtocol } from 'aws-cdk-lib/aws-elasticloadbalancing';

const lb = new LoadBalancer(this, 'elb-ssl', {
  vpc,
  internetFacing: true,
  healthCheck: {
    port: 80,
  },
  listeners: [
    {
      externalPort:10000,
      externalProtocol:LoadBalancingProtocol.SSL,
      internalPort:10000
    }]
});

lb.addListener({
  externalPort:10001,
  externalProtocol:LoadBalancingProtocol.SSL,
  internalPort:10001
});
lb.addListener({
  externalPort:10002,
  externalProtocol:LoadBalancingProtocol.HTTPS,
  internalPort:10002
});

For aws-cdk-lib.aws-elasticache.CfnReplicationGroup:

import { CfnReplicationGroup } from 'aws-cdk-lib/aws-elasticache';

new CfnReplicationGroup(this, 'encrypted-explicit', {
  replicationGroupDescription: 'example',
  transitEncryptionEnabled: true
});

For aws-cdk-lib.aws-kinesis.Stream:

import { Stream } from 'aws-cdk-lib/aws-kinesis';

new Stream(this, 'stream-implicit-encrypted');

new Stream(this, 'stream-explicit-encrypted-selfmanaged', {
  encryption: StreamEncryption.KMS,
  encryptionKey: encryptionKey,
});

new Stream(this, 'stream-explicit-encrypted-managed', {
  encryption: StreamEncryption.MANAGED
});

For aws-cdk-lib.aws-kinesis.CfnStream:

import { CfnStream } from 'aws-cdk-lib/aws-kinesis';

new CfnStream(this, 'cfnstream-explicit-encrypted', {
  streamEncryption: {
    encryptionType: encryptionType,
    keyId: encryptionKey.keyId,
  }
});

Exceptions

No issue is reported for the following cases because they are not considered sensitive:

See

Documentation

Articles & blog posts

Standards