CVE-2025-22425 - Local Privilege Escalation in InstallStart.java via Permissions Bypass

CVE-2025-22425 is a vulnerability affecting an Android component called InstallStart.java. This security issue allows a local user to bypass app permissions due to incorrect input validation during the creation phase of the install process (inside the onCreate method). With minimal interaction from the user, an attacker could escalate their local privileges without needing extra execution privileges.

This article breaks down the technical details behind the vulnerability, key code patterns, exploitation steps, and how developers and users can protect themselves.

The Vulnerable Code

The vulnerability lies in the way InstallStart.java handles certain input values during the installation process. An attacker can craft an Intent that, when triggered, causes the installer to bypass normal permission checks.

Here's an example of how the problematic code might look

// InstallStart.java (simplified example)
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    Intent intent = getIntent();
    String installPath = intent.getStringExtra("install_path");

    // Vulnerable: No validation on installPath!
    if (installPath != null) {
        File target = new File(installPath);
        if (target.exists()) {
            startInstallation(target);
        }
    }
}

The code does not check if the installPath comes from a trusted source.

- No validation is done to ensure the installPath points to a legitimate app package or within a safe directory.
- A malicious app can craft an Intent with a path pointing to sensitive locations, tricking the installer into acting on files it shouldn't.

Craft a Malicious App:

The attacker creates an app that sends an Intent to InstallStart with a specially crafted install_path pointing to a file under their control, or to a sensitive system file.

);

exploitIntent.putExtra("install_path", "/data/data/com.attacker.app/files/evil.apk");

User Interaction:

The user must accept the installation prompt. (Attackers might use trickery or overlays to encourage action.)

Gain Extra Privileges:

Because the installer doesn't properly check the path, it processes the attacker’s APK or file, possibly granting it extra privileges (like privileged permissions) that are normally restricted.

Potential Impact

- Local Privilege Escalation: Malicious apps can install themselves or modify files with higher privileges than intended.

`java

// Safe pattern

}

private boolean isSafePath(String path) {

// Implement logic: only allow trusted directories
return path.startsWith("/data/app/") || path.startsWith("/system/app/");
}

private boolean isValidApk(File file) {

// Add APK signature and package validation here
return true; // Placeholder for actual checks
}
 --- ## References & Further Reading - Google Android Project Zero – Secure Input Validation - Android Secure Component Development Guide - Official CVE Entry for CVE-2025-22425 *(Check for updates as Mitre assigns details)* - Related issue: CVE-2019-2215 Local Privilege Escalation Analysis  - Example report on Improper Input Validation --- ## Conclusion CVE-2025-22425 demonstrates how simple coding mistakes—like improper input validation—can have serious consequences. In this case, a single unchecked field in the onCreate` method opens the door for attackers to escalate privileges locally, potentially undermining the security of the whole device. Developers should learn from this vulnerability by rigorously validating every piece of untrusted input.

Stay safe, and always think twice before granting sensitive permissions!

Timeline

Published on: 09/04/2025 18:15:39 UTC
Last modified on: 09/05/2025 18:56:05 UTC