CVE-2021-27935 : What You Need to Know

AdGuard before version 0.105.2 has a critical security issue where an attacker with access to a user's cookie can offline brute force their password due to storing the password hash in the cookie.

Understanding CVE-2021-27935

This section provides insights into the nature and impact of the vulnerability.

What is CVE-2021-27935?

The CVE-2021-27935 vulnerability is a security flaw found in AdGuard versions prior to 0.105.2 that allows attackers to conduct offline password brute-force attacks using hashed passwords stored in user cookies.

The Impact of CVE-2021-27935

The vulnerability exposes users to the risk of having their passwords compromised by malicious actors who gain access to their cookies. This could lead to unauthorized access to sensitive information and accounts.

Technical Details of CVE-2021-27935

Explore the specific technical aspects of the CVE-2021-27935 vulnerability.

Vulnerability Description

AdGuard's vulnerability lies in the insecure storage of password hashes in user cookies, enabling attackers to crack passwords offline once the cookie is obtained.

Affected Systems and Versions

All versions of AdGuard before 0.105.2 are affected by this vulnerability, putting users of these versions at risk of password compromise.

Exploitation Mechanism

Attackers exploit the vulnerability by obtaining a user's cookie, extracting the password hash from it, and then conducting offline brute-force attacks to decipher the password.

Mitigation and Prevention

Learn how to mitigate the risks posed by CVE-2021-27935 and prevent potential exploitation.

Immediate Steps to Take

Users should update their AdGuard software to version 0.105.2 or above to patch the vulnerability and protect their passwords from offline brute-force attacks.

Long-Term Security Practices

In addition to updating the software, users are advised to follow best security practices such as using strong, unique passwords and enabling two-factor authentication to enhance their account security.

Patching and Updates

Regularly checking for software updates and promptly applying patches is crucial to safeguarding against known vulnerabilities like CVE-2021-27935.