CVE-2021-20733 : Security Advisory and Response

A detailed overview of the Improper authorization vulnerability in the あすけんダイエット (asken diet) for Android versions v.3.0.0 to v.4.2.x, allowing remote attackers to manipulate user access.

Understanding CVE-2021-20733

This section covers the impacts, technical details, and mitigation strategies related to CVE-2021-20733.

What is CVE-2021-20733?

The CVE-2021-20733 vulnerability involves an Improper Authorization issue in the handler for the custom URL scheme, present in the あすけんダイエット (asken diet) for Android versions v.3.0.0 to v.4.2.x. This security flaw allows a malicious actor to manipulate the handler and redirect users to malicious websites without their consent.

The Impact of CVE-2021-20733

The vulnerability enables remote attackers to craft URLs that exploit the handler's improper authorization, leading unsuspecting users to access arbitrary websites controlled by the attacker. This could result in information leakage, phishing attacks, or further compromise of the user's device.

Technical Details of CVE-2021-20733

To understand the vulnerability further, the following technical aspects are crucial for assessment and remediation.

Vulnerability Description

The vulnerability arises from the improper authorization mechanism in the handler for the custom URL scheme. Attackers can abuse this flaw to execute unauthorized actions on the app, compromising user security.

Affected Systems and Versions

The affected systems include あすけんダイエット (asken diet) for Android versions from v.3.0.0 to v.4.2.x. Users with these versions are at risk of exploitation until the necessary security measures are implemented.

Exploitation Mechanism

The exploitation involves manipulating the custom URL scheme handler through specially crafted URLs, diverting users to malicious sites and undermining the app's security controls.

Mitigation and Prevention

Protecting systems from CVE-2021-20733 requires immediate actions and long-term security practices to prevent exploitation.

Immediate Steps to Take

Users and administrators must refrain from clicking on untrusted URLs and disable the vulnerable application until a patch is available. Updating the app to a secure version is crucial.

Long-Term Security Practices

Developers should implement secure authorization mechanisms, validate and sanitize inputs, and conduct regular security audits to identify and address similar vulnerabilities proactively.

Patching and Updates

As a preventive measure, users should apply security patches provided by the vendor promptly. Ensuring that the application is up-to-date with the latest security fixes will mitigate the risk of exploitation.