CVE-2018-9461: Exploring the Race Condition Vulnerability in ShareIntentActivity.java

In the world of cybersecurity, identifying and addressing vulnerabilities before they are discovered and exploited by malicious actors is crucial. One such vulnerability, CVE-2018-9461, was discovered in the ShareIntentActivity.java file, which allowed an app to read files in the messages app due to a race condition. This vulnerability could lead to a local escalation of privilege without needing any additional execution privileges and did not require user interaction for exploitation. In this article, we will discuss the details of this vulnerability, show code snippets that illustrate the issue and provide links to original references for further information.

Code Snippet

In the affected ShareIntentActivity.java file, the vulnerability was present within the onAttachFragment method. The following code snippet illustrates the main parts of the method where the issue was identified:

@Override
public void onAttachFragment(Fragment fragment) {
  if (fragment instanceof ShareMethodFragment) {
    ShareMethodFragment smf = (ShareMethodFragment) fragment;
    // Race condition vulnerability starts here
    smf.setShareMethodListener(this);
  }
}

As seen in the code snippet, a race condition exists between the time the ShareMethodFragment instance is created and when the setShareMethodListener() method is called. An attacker can potentially exploit this race condition to read files from the messages app and escalate privileges locally.

Exploit Details

To better understand the exploit details, let us walk through the steps involved in the potential attack:

1. An attacker creates a malicious app targeting the ShareMethodFragment class to exploit the race condition.

2. The malicious app awaits the moment when the ShareMethodFragment instance is created and the race condition occurs.

3. Before the setShareMethodListener() method is called, the malicious app intervenes, exploiting the vulnerability by accessing and reading files from the messages app.

4. The attacker successfully escalates their privileges locally without requiring any additional execution privileges or user interaction.

For more information on CVE-2018-9461, you can refer to the following sources

- CVE-2018-9461: NIST National Vulnerability Database (NVD) Entry
- Android Security Bulletin - August 2018
- Google's Issue Tracker for CVE-2018-9461

Conclusion

CVE-2018-9461 is an example of how a seemingly small race condition can lead to security vulnerabilities that could be exploited by attackers. Ensuring that code is written with security in mind and vulnerabilities are diligently tracked and patched is essential for protecting user data and maintaining trust in software systems. By understanding the details and implications of such vulnerabilities, developers can better implement safeguards and prevent future exploitation.

Timeline

Published on: 01/18/2025 00:15:25 UTC
Last modified on: 03/18/2025 21:15:22 UTC