Backdoor.Quasar
ThreatDown is now the name of the Malwarebytes line of business products. References to Malwarebytes below reflect the amazing technology used to first identify the threat.
Short bio
Backdoor.Quasar is Malwarebytes’ detection name for a large family of Remote Access Trojans (RATs) that target Windows systems.
Type of infection
Backdoor.Quasar is a lightweight, publicly available open-source Remote Access Trojan (RAT) which primarily targets Windows OS systems.
Backdoor.Quasar is often distributed via malicious attachments in phishing emails, but operators are free to choose their own ways to spread the RAT.
Business remediation
How to remove Backdoor.Quasar with the Malwarebytes Nebula console
You can use the Malwarebytes Anti-Malware Nebula console to scan endpoints.

Nebula endpoint tasks menu
Choose the Scan + Quarantine option. Afterwards you can check the Detections page to see which threats were found.

On the Quarantine page you can see which threats were quarantined and restore them if necessary.

Home remediation
Malwarebytes can remove Backdoor.Quasar for you if you decide that you want to get rid of it.