You cannot download the Microsoft Safety Scanner to your computer because your computer is infected by malware.
If a malware infection is preventing you from downloading the Microsoft Safety Scanner to your computer, use one of the following methods to download and run the tool.
Method 1: Run the Microsoft Safety Scanner from removable media
Save the Microsoft Safety Scanner to removable media on an uninfected computer, and then run the tool on the infected computer. To do this, follow these steps:
On an uninfected computer, browse to the Microsoft Safety Scanner download page, and then click Download Now.
Click Save as, and then save the file to a USB flash drive or a blank CD.
After the file download is finished, run the file on the infected computer. To do this, insert the USB flash drive or CD into the infected computer, and then double-click the downloaded file on the removable media.
If you are prompted to run the file as an administrator, click Yes.
Read the license agreement. If you agree, select the check box next to Accept all terms of the preceding license agreement, click Next, and then follow the onscreen instructions through the next few steps.
Select the kind of scan you want to run and the folders that you want to scan, and then click Next. If the tool finds any infections, it will identify the malware that it has found and then remove that malware from your computer.
After the tool has finished running, you must restart computer.
Update your existing security software, and then run a full scan.
Note The Microsoft Safety Scanner expires after 10 days. To rerun a scan that uses the latest antimalware definitions, download and run the Microsoft Safety Scanner again.
Method 2: Contact Microsoft Support
A Microsoft Support agent may be able to download Microsoft Safety Scanner to your computer remotely. To try this method, contact Microsoft Support to get live assisted support.
Please inform your Support agent about which version of Windows you are using and reference this Microsoft Knowledge Base article to the agent.
The Microsoft Safety Scanner is a free security tool that provides on-demand scanning. This tool helps remove malicious and potentially unwanted software that may have disabled your existing antimalware software or that may prevent you from downloading or installing additional updates or software.
For more information about how to protect your computer from botnets and other forms of malware that can prevent you from downloading or installing updates or other software, see Microsoft Virus Protection and Windows Security Support.