CVE-2023-20944 - Escalation of Privilege through Unsafe Deserialization in Android's ChooseTypeAndAccountActivity.java

The vulnerability CVE-2023-20944 refers to a possible escalation of privilege in Android's ChooseTypeAndAccountActivity.java due to unsafe deserialization. A local attacker could exploit this vulnerability to gain unauthorized privilege access on the target device, without any additional permissions and without any user interaction. The affected Android versions include Android-10, Android-11, Android-12, Android-12L, and Android-13.

Background

Deserialization is the process of converting binary data back into its original object form. However, when this process is handled unsafely, it can lead to vulnerabilities. In this case, the vulnerability (CVE-2023-20944) affects the ChooseTypeAndAccountActivity.java file in Android.

Code Snippet

Here is a code snippet from ChooseTypeAndAccountActivity.java, which demonstrates the unsafe deserialization issue:

public class ChooseTypeAndAccountActivity extends AccountActivity {
  ...
  private void deserializeData(Intent intent) {
    if (!intent.hasExtra(EXTRA_ALLOWED_ACCOUNT_TYPES)) {
      mSetOfAllowableAccountTypes = null;
    } else {
      ArrayList<String> serializable = intent.getStringArrayListExtra(EXTRA_ALLOWED_ACCOUNT_TYPES);
      mSetOfAllowableAccountTypes = new HashSet<>(serializable);
    }
  }
  ...
}

In this code snippet, we can observe that the function deserializeData() is called, without any mechanism to properly validate the input data. This could lead to an attacker being able to craft malicious input data that would exploit the vulnerability, allowing them to gain unauthorized access to sensitive data and escalate their privileges on the target device.

Exploit Details

To exploit this vulnerability, an attacker would need to craft a malicious app that could perform unsafe deserialization on the target Android device. Since no user interaction is required for exploitation, the attacker could potentially exploit this vulnerability silently, without raising any suspicion.

The escalation of privilege would enable the attacker to perform unauthorized actions on the device, such as accessing sensitive user data or modifying the device's settings. It is crucial to note that this vulnerability does not grant the attacker any additional execution privileges, meaning they would still be constrained by the existing permission model of the Android system.

Original References

The original advisory for CVE-2023-20944 can be found at the following Android Security Bulletin link:

- Android Security Bulletin - March 2023

The Android ID associated with this vulnerability is A-244154558.

Recommendations

To mitigate the risk of this vulnerability, it is strongly recommended to keep your Android device and applications updated with the latest security patches from your device manufacturer or Google. It is also essential to exercise caution when downloading or installing apps from unknown sources, as these may contain malware that could exploit vulnerabilities such as CVE-2023-20944.

Further, developers should pay close attention to their code when dealing with deserialization to ensure that they implement proper input validation and safe techniques when handling binary data.

Timeline

Published on: 02/28/2023 17:15:00 UTC
Last modified on: 03/06/2023 19:39:00 UTC