Category :


Type :


Aliases :

TrojanDownloader.Win32.Xombe, Trojan.Win32.Xombe


Xombe trojan downloader was sent as an email attachment to a large amount of people on 9th of January 2004. When run, the trojan downloader connects to Internet and downloads and activates another trojan on a victim's computer. UPDATE ON 10TH OF JANUARY 2003 The site used by this trojan ( has now been disabled and this trojan won't be able to function any more.


Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note: You need administrative rights to change the settings.

Technical Details

Xombe trojan downloader was sent to a large amount of people in the email that looks like that:

Windows XP Service Pack 1 (Express) - Critical Update.
Window Update has determined that you are running a beta version
of Windows XP Service Pack 1 (SP1).
To help improve the
stability of your computer, Microsoft recommends that you remove
the beta version of Windows XP SP1 and re-install Windows XP
If you cannot remove the beta version, you should still
reinstall Windows XP SP1.
Windows XP SP1 provides the latest security, reliability, and
performance updates to the Windows XP family of operating
systems. Windows XP SP1 is designed to ensure Windows XP
platform compatibility with newly released software and
hardware, and includes updates to resolve issues discovered by
customers or by Microsoft's internal testing team.
The maximum download size is approximately 3 MB, however the
size of the download and time required may be less for computers
that have had updates previously installed.
To minimize the download time needed for installation, setup
will only download those files which are required to bring your
computer up to date.
Windows XP SP1 includes Internet Explorer 6
Anti-virus software programs may interfere with the
installation of Windows XP SP1.
Please disable anti-virus
software while installing the service pack.
Just run the file winxp_sp1.exe in attach and make sure to
restart your PC after installation will be completed.
(c) 2004 Microsoft Corporation. All rights reserved. Terms of
Use Privacy Statement

When the trojan downloader is run by a user, it connects to Internet and downloads another trojan.

Trojan components

The trojan consists of three components:


This file is the first-stage downloader that comes in email. The only purpose of this program is to fetch the main component of the trojan and plant in on the target system.


This is the main component of the trojan. It is a general-purpose downloader application that is controlled through a certain web page. It can fetch arbitrary files from the Internet and install them on the infected system.

msvchost.exe is installed to the System Directory on the infected computer and added to the registry as [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\mssvc] When the trojan was first intercepted the website instructed the clients to download a DLL file.


http_f.dll is an HTTP client which is apparently used to perform a Distibuted Denial-of-Service attack on a website that hosts forums. This file is also dropped to the System Directory, just like the main component.