How can i find about that scan? Sure it is an on demand scan that will scan the locations known for installing malware, but ELAM is designed as a way to check drivers before they load. Without ELAM Avast is prone just as any other AV product that doesn't use ELAM. Once the rootkits load they are able to avoid even specialized on demand scans which target the specific locations known for rootkit infections. Boot time scan will find them, but ELAM is a real time scan while the boot time is an on demand.