In this post, we will discuss a recently discovered vulnerability, CVE-2024-40676, that affects the checkKeyIntent function within AccountManagerService.java. This vulnerability allows an attacker to bypass the intent security check and potentially install an unknown and potentially malicious application on a device. We will explore how this vulnerability can be exploited, the technical details of the vulnerability, and any available patches to mitigate the risk.

The Vulnerability

The vulnerability is present in the checkKeyIntent function of the AccountManagerService.java file, and it allows for a confused deputy scenario. A confused deputy refers to a situation where a component unwittingly carries out the malicious intentions of an attacker. In this specific case, a malicious app could abuse the vulnerability to bypass security checks and escalate its privileges on the targeted device.

Here's the code snippet affected by this vulnerability

protected void checkKeyIntent(String accountType, Intent intent) {
    ...
    resolveInfo = mPackageManager.resolveIntent(intent, packageName, , userId);
    if(resolveInfo == null) {
        throw new SecurityException(...);
    }
    String componentPackageName = resolveInfo.getComponentInfo().packageName;
    if(!accessorPackageName.equals(componentPackageName)) {
        throw new SecurityException(...);
    }
}

From the code snippet, you can observe that the vulnerable checkKeyIntent function checks for a valid resolveInfo object and whether the accessorPackageName is equal to the componentPackageName. However, it neglects to verify the authenticity of the calling package, allowing a malicious package to act as a confused deputy and escalate privileges.

Exploitation Details

To exploit this vulnerability, an attacker would need to create a malicious application that leverages the confused deputy scenario created by the vulnerable checkKeyIntent function. While user interaction is not needed to exploit this vulnerability, it is worth mentioning that a targeted user would still need to install the malicious application.

Once the malicious application is installed, it can abuse the AccountManagerService service by invoking the vulnerable checkKeyIntent function to bypass intent security checks. Consequently, the attacker could potentially install and execute further malicious applications without the user's knowledge.

Below are the original references where the vulnerability was reported

- Android Security Bulletin
- National Vulnerability Database (NIST)

Patch Information

This vulnerability has been assigned as CVE-2024-40676, and Google has addressed this issue in the Android security bulletin. It is highly recommended to check for updates and apply patches to your Android devices as soon as possible to mitigate the risk of this vulnerability. Device manufacturers should also ensure that they are distributing the latest security updates to their users.

Conclusion

CVE-2024-40676 is a critical vulnerability that can allow an attacker to bypass the intent security check and install an unknown application due to a confused deputy. As always, it is essential to keep your device software up to date and regularly check for security updates to protect yourself from such vulnerabilities.

Timeline

Published on: 01/28/2025 20:15:49 UTC
Last modified on: 02/06/2025 16:15:37 UTC