A potent security vulnerability, identified as CVE-2023-4573, has been recently discovered that affects multiple versions of Mozilla Firefox and Thunderbird. The issue occurs during the handling of rendering data received over IPC (Inter-process communication), which may lead to a use-after-free scenario, causing a potentially exploitable crash.

This blog post will provide an in-depth analysis of the vulnerability and share information about possible exploits, including code snippets, original references, and an overview of affected versions.

Exploit Details

The root cause of this vulnerability is the handling of mStream instances while processing the rendering data received over IPC. In certain scenarios, mStream might get destroyed immediately after being initialized, leading to a use-after-free vulnerability. Attackers can exploit this flaw to execute arbitrary code or crash the application, resulting in denial of service (DoS).

Here's a sample code snippet that demonstrates the vulnerable code path

void SomeClass::ProcessRenderingData(const IPCData& aData) {
  ...
  RefPtr<SomeStream> mStream = new SomeStream();
  ...
  InitStreamWithReceivedData(mStream, aData);
  ...
  if (some_condition) {
    // This line destroys mStream.
    mStream = nullptr;
  }
  ...
  // Use of mStream after it might have been destroyed.
  mStream->WriteRenderingData(aData);
  ...
}

As shown in the code above, the mStream instance might get destroyed under certain conditions. However, later in the function, mStream->WriteRenderingData(aData) is called, resulting in a use-after-free vulnerability.

Original References

Mozilla has acknowledged this vulnerability and assigned it with CVE-2023-4573. You can find more details about the vulnerability in the official advisories:

- Mozilla Foundation Security Advisory 2023-01
- Mozilla Foundation Security Advisory 2023-02
- Mozilla Foundation Security Advisory 2023-03

Mitigations and patches for the affected software versions can be found within these advisories.

Thunderbird 115.2 or higher

2. Be cautious when visiting untrusted websites or opening suspicious email attachments, as attackers could leverage those channels to exploit this vulnerability.

3. Maintain a strong and updated security solution to protect your systems from malware and other cyber threats that could potentially exploit security flaws.

Conclusion

CVE-2023-4573 is a critical use-after-free vulnerability affecting multiple versions of Mozilla Firefox and Thunderbird applications. Users and administrators need to take immediate action to patch their systems and adopt the best security practices to avoid falling victim to potential exploits. Stay informed, and stay safe!

Timeline

Published on: 09/11/2023 08:15:00 UTC
Last modified on: 09/13/2023 11:15:00 UTC