Published Dec 14, 2010 | Updated Nov 07, 2017


Severe |Detected with Windows Defender Antivirus

Aliases: JS/Downldr.BQ (other) TR/Script.158662 (Avira) Trojan.Script.158662 (BitDefender) BackDoor.Qbotd.1 (Dr.Web) JS/TrojanDownloader.Agent.NQJ (ESET) Trojan-Downloader.JS.Qakbot (Ikarus) JS/Downloader-AH (McAfee) Bck/QBot.M (Panda) (Rising AV) Troj/Dloadr-CUV (Sophos) Trojan-Downloader.JS.Agent.efb (Sunbelt Software) JS_OBFUS.DE (Trend Micro)


TrojanDownloader:JS/Qakbot.A is a JavaScript trojan that attempts to download and install Backdoor:Win32/Qakbot.gen!A

The Qakbot family is a multi-component family of trojans that connect to a remote server, allowing an attacker to access the infected system. For more information on the Qakbot family, see the Win32/Qakbot family description elsewhere in the encyclopedia.

Use the following free Microsoft software to detect and remove this threat:

You should also run a full scan. A full scan might find hidden malware. 

Use cloud protection 

Use cloud protection to help guard against the latest malware threats. It’s turned on by default for Microsoft Security Essentials and Windows Defender Antivirus for Windows 10. 

Go to Settings > Update & security > Windows Defender > Windows Defender Security Center > Virus & threat protection and make sure that your Cloud-based Protection settings is turned On

Get more help

You can also visit our advanced troubleshooting page or search the Microsoft virus and malware community for more help.

If you’re using Windows XP, see our Windows XP end of support page.

Follow us