CVE-2021-25263 : Security Advisory and Response

A local privilege vulnerability in Yandex Browser for Windows prior to version 21.9.0.390 allows attackers to execute arbitrary code with SYSTEM privileges. This CVE was published on August 17, 2021, and affects Yandex Browser (Desktop).

Understanding CVE-2021-25263

This section delves into the details of CVE-2021-25263, outlining the vulnerability, its impact, technical aspects, and mitigation strategies.

What is CVE-2021-25263?

CVE-2021-25263 refers to a local privilege vulnerability in Yandex Browser for Windows before version 21.9.0.390. This flaw enables a local attacker with low privileges to execute arbitrary code with SYSTEM privileges by manipulating files during the browser update process.

The Impact of CVE-2021-25263

The impact of this vulnerability is significant as it allows an attacker to escalate their privileges from low to SYSTEM level, gaining extensive control over the affected system. This can lead to unauthorized access, data theft, and system compromise.

Technical Details of CVE-2021-25263

This section provides in-depth technical insights into CVE-2021-25263, including the vulnerability description, affected systems, and exploitation mechanism.

Vulnerability Description

The vulnerability in Yandex Browser allows a local attacker to exploit insecure file permissions during the update process, leading to arbitrary code execution with elevated privileges.

Affected Systems and Versions

Yandex Browser (Desktop) versions prior to 21.9.0.390 are impacted by this vulnerability. Users of these versions are at risk of exploitation by attackers aiming to elevate their privileges.

Exploitation Mechanism

Attackers exploit the insecure file permissions present in the directory used during the Yandex Browser update process. By manipulating these files, they can execute malicious code with SYSTEM privileges.

Mitigation and Prevention

To mitigate the risks associated with CVE-2021-25263, users and organizations are advised to take immediate action by following security best practices and applying relevant patches and updates.

Immediate Steps to Take

Users should update their Yandex Browser to version 21.9.0.390 or above to address the vulnerability. Additionally, monitoring system activity for any suspicious behavior is recommended.

Long-Term Security Practices

Practicing the principle of least privilege, implementing strong authentication mechanisms, and conducting regular security audits can enhance overall security posture and prevent similar exploits.

Patching and Updates

Yandex Browser users should regularly check for security updates released by the vendor and apply them promptly to ensure protection against known vulnerabilities.