Published Apr 13, 2010 | Updated Sep 15, 2017


Severe |Detected with Windows Defender Antivirus

Aliases: Win-Trojan/Koobface.225280 (AhnLab) Trojan-Dropper.Win32.Koobface.i (Kaspersky) W32/Koobface.GSQ (Norman) Trojan.DR.Koobface.DRK (VirusBuster) TR/Drop.Koobface.J.13 (Avira) Trojan-Dropper.Win32.Koobface (Ikarus) W32/Koobface.KA.worm (Panda) W32.Koobface.A (Symantec)


TrojanDropper:Win32/Koobface.J is the detection for the malware dropper component of certain members of the Win32/Koobface family. It drops and installs the proxy and driver components.
TrojanDropper:Win32/Koobface.J also modifies the computer's firewall settings by allowing its proxy component to bypass the firewall, and adding a firewall exception for a certain port.
Manual removal is not recommended for this threat. To detect and remove this threat and other malicious software that may have been installed, run a full-system scan with an up-to-date antivirus product such as Microsoft Security Essentials, or the Microsoft Safety Scanner. For more information about using antivirus software, see
Additional remediation steps required for this threat
The Domain Name System (DNS) is used (among other things) to map domain names to IP addresses - that is, to map human-readable domain names to machine-readable IP addresses. When a user attempts to visit a particular URL, a browser uses DNS servers to find the correct IP address of the requested domain. When a user is directed to a malicious server that is not part of the authoritative Domain Name System, an attacker can provide incorrect IP addresses at their choice to map to particular domain names, thus directing the user to possibly bogus or malicious sites without the affected user's knowledge.
This threat may modify DNS settings on the host computer, thus the following steps may be required after the its removal is complete:
  • If the computer has a network interface that does not receive a configuration using DHCP, reset the DNS configuration if necessary. For information on configuring TCP/IP to use DNS in Windows XP, see
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