On December 20, 2023, Google Chrome users received an urgent high-severity patch for a critical vulnerability tracked as CVE-2023-7024. This bug was traced back to a heap buffer overflow in Chrome’s implementation of WebRTC (Web Real-Time Communication). By exploiting this vulnerability, a remote attacker could potentially cause heap corruption and execute malicious code by simply tricking someone into visiting a crafted web page.

Let’s break down how CVE-2023-7024 works, the possible exploitation methods, and what you need to know to stay safe.

What Is WebRTC and Why Does It Matter?

WebRTC is a free, open-source project providing web browsers and mobile apps with real-time communication via simple APIs. It powers things like video calls on Google Meet, Discord’s voice chat, or voice assistants in the browser—making it quite a target for attackers.

Heap: This is a region of memory software uses for temporary stuff.

- Buffer overflow: Happens when software writes more data to a spot in memory than expected, spilling into adjacent memory and overwriting it.

If you trick a program into overwriting its own data this way (e.g., by sending the right type of message at the right time), you can potentially hijack it.

The vulnerable code lives in Chrome’s WebRTC library.

- A specially crafted HTML/JavaScript page can send certain media data (for example, via a crafted RTP packet or SDP offer) to trigger this bug.

A Peek Into the Code

Here’s a super-simplified snippet showing what typically causes a heap buffer overflow in C++ (used by WebRTC):

// Vulnerable pattern in C++
char buffer[64];
strcpy(buffer, user_supplied_input); // if input is longer than 64 bytes - overflow!

In the real WebRTC case, a bug like this could be lurking in the network packet handling code, where Chrome doesn’t check the data’s size before copying it.

Proof-of-Concept (PoC) Exploit (Educational Purpose Only)

Note: The actual PoC code is not public for this vulnerability, but here’s an illustration of how such an attack works:

<!-- Crafted HTML for triggering the bug in a vulnerable Chrome version -->
<script>
  // Constructing raw media data with extra-long portions to overflow
  let peer = new RTCPeerConnection();
  peer.createDataChannel("overflow", {maxPacketLifeTime: 9999999});
  // Simulate sending/receiving malformed SDP or ICE candidates
  let sdp = "v=\no=-   IN IP4 127...1\ns=+\nt= \nm=audio 9 RTP/AVP \nc=IN IP4 127...1\na=sendrecv\n"+ "a=".repeat(10000);
  peer.setRemoteDescription({ type: "offer", sdp: sdp });
</script>

*This script is conceptual: the true exploit would target more specific WebRTC internals. Real-world attackers might use a crafted media connection too.*

Exploitation Details

Attack Scenario:

A bug in how Chrome copies this data leads to an overwrite in heap memory.

5. The attacker uses this heap corruption to possibly execute code, crash the browser, or escalate to broader system compromise.

Anyone running Chrome (or any Chromium-based browser) prior to 120..6099.129.

- Browsers based on Chromium, like Edge, Opera, and Brave—especially if they didn’t quickly issue updates.

Why Is This Severe?

- Remote code execution (RCE): This means attackers could run code on your computer simply if you visit the wrong website.
- No user interaction needed: You didn't have to download or click anything—just visit a malicious page.

References & More Info

- Chromium Security Advisory (CVE-2023-7024)
- NIST NVD CVE-2023-7024 entry
- Official WebRTC Project
- Heap Buffer Overflow explained

How To Protect Yourself

1. Update now! Make sure your Chrome or Chromium-based browser is at least *120..6099.129* (or the latest available update).

Keep your OS updated: Security at more than one level helps if the browser is compromised.

To check your Chrome version:
Go to Settings > About Chrome or paste chrome://settings/help in your address bar.

Conclusion

*CVE-2023-7024* is a real-life reminder of how even popular, actively maintained software can have severe bugs. WebRTC is powerful, but it’s also a juicy target. Chrome’s quick fix blunted the danger, but make sure you’re up to date—don’t get caught off guard!

Stay patched, stay safe! If you want to dive deeper into WebRTC security, check out Google’s WebRTC Security Guide.

Timeline

Published on: 12/21/2023 23:15:11 UTC
Last modified on: 01/03/2024 02:00:01 UTC