Skip to main content

Trojan:W32/Qhost

Classification

Category:

Malware

Type:

Trojan

Aliases:

  • Trojan.Win32.Qhost

Summary

This is network worm with backdoor capabilities, which spreads itself under Win32 systems. The worm was reported in-the-wild in July-August, 2000. The worm itself is Win32 executable file and about 120K long, written in MS Visual C++.

Removal

Technical Details

Some malicious applications will modify the Windows HOSTS file in an attempt to block access to antivirus vendor web and update servers. As a result, the websites of several antivirus vendors may become inaccessible and some antivirus programs may stop receiving updates. The Windows HOSTS file typically contains information only about the localhost. Some malware variants add more entries to the HOSTS file, attempting to block access to antivirus websites and update servers.

Example

A normal HOSTS file will appear as follows:

# Copyright (c) 1993-1999 Microsoft Corp. # # This is a sample HOSTS file used by Microsoft TCP/IP for Windows. # # This file contains the mappings of IP addresses to host names. Each # entry should be kept on an individual line. The IP address should # be placed in the first column followed by the corresponding host name. # The IP address and the host name should be separated by at least one # space. # # Additionally, comments (such as these) may be inserted on individual # lines or following the machine name denoted by a '#' symbol. # # For example: # # 102.54.94.97 rhino.acme.com # source server # 38.25.63.10 x.acme.com # x client host 127.0.0.1 localhost

The typical file path is:

  • C:\%windir%\system32\drivers\etc\hosts

A malware-modified version of the HOSTS file will contain additional entries:

  • 127.0.0.1 avp.com
  • 127.0.0.1 ca.com
  • 127.0.0.1 customer.symantec.com
  • 127.0.0.1 dispatch.mcafee.com
  • 127.0.0.1 download.mcafee.com
  • 127.0.0.1 f-secure.com
  • 127.0.0.1 kaspersky.com
  • 127.0.0.1 liveupdate.symantec.com
  • 127.0.0.1 liveupdate.symantecliveupdate.com
  • 127.0.0.1 localhost
  • 127.0.0.1 mast.mcafee.com
  • 127.0.0.1 mcafee.com
  • 127.0.0.1 my-etrust.com
  • 127.0.0.1 nai.com
  • 127.0.0.1 networkassociates.com
  • 127.0.0.1 rads.mcafee.com
  • 127.0.0.1 secure.nai.com
  • 127.0.0.1 securityresponse.symantec.com
  • 127.0.0.1 sophos.com
  • 127.0.0.1 symantec.com
  • 127.0.0.1 trendmicro.com
  • 127.0.0.1 update.symantec.com
  • 127.0.0.1 updates.symantec.com
  • 127.0.0.1 us.mcafee.com
  • 127.0.0.1 viruslist.com
  • 127.0.0.1 viruslist.com
  • 127.0.0.1 www.avp.com
  • 127.0.0.1 www.ca.com
  • 127.0.0.1 www.f-secure.com
  • 127.0.0.1 www.kaspersky.com
  • 127.0.0.1 www.mcafee.com
  • 127.0.0.1 www.my-etrust.com
  • 127.0.0.1 www.nai.com
  • 127.0.0.1 www.networkassociates.com
  • 127.0.0.1 www.sophos.com
  • 127.0.0.1 www.symantec.com
  • 127.0.0.1 www.trendmicro.com
  • 127.0.0.1 www.viruslist.com

Websites or servers configured to an IP Address of 127.0.0.1 will loop back to the local machine, making them unreachable.

Protect your devices from malware with F‑Secure Total

Protecting your devices from malicious software is essential for maintaining online security. F‑Secure Total makes this easy, helping you to secure your devices in a brilliantly simple way.

  • Award‑winning antivirus and malware protection

  • Online browsing, banking, and shopping protection

  • 24/7 online identity and data breach monitoring

  • Unlimited VPN service to safe­guard your privacy

  • Password manager with private data protection

Choose how many devices you want to protect to get started.

  • Free customer support

  • Cancel anytime

  • The trial does not obligate you to buy the product

After 30 days your subscription will renew automatically for one year at €69.99.

More Support

Community

Ask questions in our Community.

User guides

Check the user guide for instructions.

Contact Support

Chat with with or call an agent.

Submit a Sample

Submit a file or URL for analysis.