Win32/Onescan is offered as antivirus, which claims to protect your system and help you to stay safe while browsing. But actually Win32/Onescan is a rogue program, that can reach your computer after of visiting some infected websites, downloading freeware from the web or opening suspicious e-mail attachments. If you notice any signs of Win32/Onescan presence on you PC, it means that your antivirus has been successfully bypassed and now your PC is vulnerable for other malicious intrusions.