Hello everyone,

Today we are going to discuss CVE-2022-25345, which is a Denial of Service (DoS) vulnerability discovered in the popular @discordjs/opus package. This vulnerability can cause a hard crash in all versions of the package when encoding data using an encoder with zero channels or a non-initialized buffer. In this post, we will explore the details of this vulnerability, check out code snippets demonstrating the issue, and discuss how to mitigate this risk by updating your code and packages.

Vulnerability Details

@discordjs/opus is one of the most widely used libraries for encoding and decoding audio data for Discord bots and applications developed using Node.js. However, researchers recently found a vulnerability that can be exploited by malicious actors to cause a Denial of Service attack simply by trying to encode data using an encoder with zero channels or a non-initialized buffer. This vulnerability has been assigned the CVE ID CVE-2022-25345.

The problem occurs in the OpusEncoder's handling of input data, specifically related to how it manages the number of channels and buffers. To understand better, let's look at the code snippet below:

const { OpusEncoder } = require('@discordjs/opus');

const encoder = new OpusEncoder(48000, ); // 48kHz and  channels
const buffer = Buffer.allocUnsafe(192); // Uninitialized buffer

encoder.encode(buffer); // Trigger the DoS vulnerability

In this snippet, we can see that the OpusEncoder object is created with channels, and a non-initialized buffer buffer is created with Buffer.allocUnsafe(192). When the encode function is executed with this buffer, the vulnerability is triggered, leading to a hard crash.

1. CVE Details: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2022-25345
2. NPM Advisory: https://npmjs.com/advisories/25345
3. GitHub Issue: https://github.com/discordjs/opus/issues/123

Exploit Details

Considering the nature of this vulnerability, exploiting it requires crafting a payload that causes Discord bots and applications to attempt encoding data using an OpusEncoder object with zero channels or a non-initialized buffer. This approach can lead to a Denial of Service attack, causing the application to crash and interrupt its services, affecting users and the overall platform.

Data containing audio files, voice data, or similar manipulated inputs can potentially trigger the vulnerability when processed by a compromised encoder.

To mitigate the risk associated with CVE-2022-25345, we suggest the following steps

1. First and foremost, monitor the official repositories for any updates or patches from the developers of the @discordjs/opus package.
2. Update your application to check the number of channels and the buffer's initialization status before passing it to the encoder. The example below demonstrates a safer approach to handling this issue:

const { OpusEncoder } = require('@discordjs/opus');

const sampleRate = 48000;
const channels = 2; // Use a positive non-zero value for channels

if (channels > ) {
  const encoder = new OpusEncoder(sampleRate, channels);
  const buffer = Buffer.alloc(192); // Use alloc instead of allocUnsafe to create an initialized buffer

  encoder.encode(buffer); // Avoid triggering the vulnerability
}

By verifying the number of channels and using Buffer.alloc() instead of Buffer.allocUnsafe(), we can mitigate the risk of encountering this vulnerability.

In conclusion, CVE-2022-25345 is a significant vulnerability that can lead to a Denial of Service attack and affects all versions of the @discordjs/opus package. Developers using this package should monitor the official channels for updates, keep their codebase updated, and implement the suggested mitigation steps to reduce the risk associated with this vulnerability.

Timeline

Published on: 06/17/2022 20:15:00 UTC
Last modified on: 06/28/2022 12:57:00 UTC