CVE-2021-39783 : Security Advisory and Response

This article provides details about CVE-2021-39783, a vulnerability in Android-12L that allows local privilege escalation without requiring additional execution privileges.

Understanding CVE-2021-39783

CVE-2021-39783 is a vulnerability in Android-12L that could potentially lead to local escalation of privilege due to a missing permission check in rcsservice.

What is CVE-2021-39783?

In rcsservice within Android-12L, a missing permission check exists, potentially allowing an attacker to modify TTY mode and escalate privileges locally without needing extra execution privileges. This vulnerability does not require user interaction for exploitation.

The Impact of CVE-2021-39783

The impact of this vulnerability is the local escalation of privilege on the affected Android-12L devices, posing a security risk to user data and system integrity.

Technical Details of CVE-2021-39783

CVE-2021-39783 presents the following technical details:

Vulnerability Description

The vulnerability in rcsservice enables the modification of TTY mode without proper permission validation, leading to local privilege escalation.

Affected Systems and Versions

Product: Android
Versions: Android-12L

Exploitation Mechanism

The exploit involves taking advantage of the missing permission check in rcsservice to modify TTY mode and elevate privileges without additional execution permissions.

Mitigation and Prevention

To address CVE-2021-39783, take the following steps:

Immediate Steps to Take

Monitor vendor updates for patches and security advisories regularly.
Apply relevant security patches promptly when available.
Restrict unnecessary permissions for applications on Android devices.

Long-Term Security Practices

Implement the principle of least privilege to limit access rights for users and applications.
Conduct regular security audits and penetration testing to identify and address vulnerabilities proactively.
Educate users about safe practices and potential security risks on Android devices.

Patching and Updates

Stay informed about security bulletins and updates from Android to ensure all relevant patches are applied promptly.