CVE-2022-47465 is a recently discovered security vulnerability in the vdsp service. This bug, which fundamentally arises from a missing permission check, allows a local attacker to cause a Denial-of-Service (DoS) on devices using this service. In this post, we’ll break down what the vulnerability is, show code snippets to illustrate the issue, discuss how it can be exploited, and what users and developers can do to stay safe.

What is vdsp?

vdsp stands for Voice Digital Signal Processor. It’s a system service found on certain mobile chipsets (like those from MediaTek), and is responsible for audio/video signal processing functionalities. This service often runs with elevated privileges because it handles critical system resources.

The Problem: Missing Permission Check

The core issue in CVE-2022-47465 is that the vdsp service doesn’t properly check whether a request sent to it is coming from a trusted app or user. In security terms, it lacks *permission enforcement*. That means any process on the local device—even a non-privileged user app—can interact with vdsp through its exposed IPC (Inter-Process Communication) interface.

This makes the device vulnerable to attacks like Denial-of-Service, where an attacker can “spam” the service with bad requests, causing it to crash, freeze, or behave abnormally.

The Vulnerable Code

Here’s an abstracted code snippet representing the vulnerable logic found in the vdsp service (pseudo-code for illustration):

// Pseudo-code for vdsp IPC handler
void handle_ipc_request(ipc_data_t *data) {
    // [MISSING] Check if caller has necessary permissions
    // process the incoming request
    do_vdsp_operation(data);
}

In secure code, there should be a permission check that looks like this

void handle_ipc_request(ipc_data_t *data, client_t *client) {
    if (!has_required_permission(client)) {
        reject_request();
        return;
    }
    do_vdsp_operation(data);
}

But in vdsp, the check (has_required_permission(client)) just isn’t there—any local process can make potentially dangerous requests.

How It’s Exploited: Local Denial-of-Service

A malicious local app on your device could send a specially-crafted request to the vdsp service. Since no privilege or permission checks are performed, the service carries out the operation—even if it’s invalid or resource-intensive. By repeating this, the attacker can:

- Crash vdsp, breaking audio/video processing for the system
- Cause high CPU/memory usage, slowing down or freezing the device

Here’s a Python-style pseudocode illustrating how a simple exploit could look

import socket
import struct

# Side note: In practice, interacting with vdsp would require knowledge 
# of the actual IPC endpoint and message format, but this pseudocode 
# illustrates the idea.
fd = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
fd.connect("/dev/vdsp_ipc")  # Hypothetical IPC endpoint

malicious_request = struct.pack("I", xdeadbeef) * 1024  # Oversized payload

while True:
    fd.send(malicious_request)  # Spam the service

Running this in a loop overwhelms vdsp until it crashes or hangs.

Official References

- NVD (National Vulnerability Database) Entry for CVE-2022-47465
- Mitre CVE Record
- MediaTek Security Advisories

Fix Status

Vendors are recommended to add robust permission checks to all IPC entry points, ensuring only privileged users can talk to sensitive services like vdsp. Users should look for system updates from their device manufacturer.

Stay safe!

If you want to dig deeper, check the links above or look for the latest security advisories for your devices and chipsets. Security is everyone’s responsibility—the more you know, the safer your devices will be!

Timeline

Published on: 04/11/2023 12:15:00 UTC
Last modified on: 04/14/2023 16:18:00 UTC