Because you trust the sender, you download and open the RAR.
The golden rule of digital hygiene is to never open unexpected attachments, even from friends. If you have already downloaded a suspicious RAR file, do not extract it. Instead, experts from the Purism community and other security forums recommend uploading the file to a multi-engine scanner like VirusTotal to check for hidden threats before touching it. haha.rar
It may attempt to shut down task managers or antivirus software to hide its presence. Because you trust the sender, you download and open the RAR