Keep in mind that these papers might not provide an actual "crack" for Avast SecureLine VPN but rather analyze the security aspects and vulnerabilities of the VPN.
Legitimate software receives regular security patches to fix vulnerabilities. For example, a previous arbitrary file creation vulnerability in Avast SecureLine (v5.5.522) was only fixed through an official update (v5.6.4982.470). Cracked versions do not get these critical fixes. Safer Alternatives avast secureline vpn crack