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TrojanDownloader:ASX/Wimad


TrojanDownloader:ASX/Wimad is a family of malicious URL script commands found in Advance Systems Format (ASF), a file format used by Windows Media, that downloads arbitrary files.



What to do now

To detect and remove this threat and other malicious software that may be installed on your computer, run a full-system scan with an appropriate, up-to-date, security solution. The following Microsoft products detect and remove this threat:

For more information on antivirus software, see http://www.microsoft.com/windows/antivirus-partners/.

Threat behavior

TrojanDownloader:ASX/Wimad is a family of malicious URL script commands found in Advance Systems Format (ASF), a file format used by Windows Media, that downloads arbitrary files.

Attack overview

In July 2008, we observed that Trojan:Win32/Gecedoc.A was capable of altering media files with the following extensions:

  • .asf
  • .mp2
  • .mp3
  • .wma
  • .wmv

The attack on media files specifically targets Advanced Systems Format's (ASF) legitimate file feature by taking advantage of the Script Command through ASF _ Script _ Command_Object defined in the ASF Header. This threat alters the media file to enable Windows Media Player to handle a malicious URL script command embedded in a stream. Thus, when the altered ASF file is played, the malicious URL is interpreted and the media player responds to the script command.

TrojanDownloader:ASX/Wimad is a detection for malicious URL script command found in altered media files.

Installation

Some variants of Wimad may arrive as an infected file; for example, infected MP3 and ASF files may be downloaded or shared through P2P file sharing networks.

Files may be infected by Trojan:Win32/Gecedoc.A; files infected by this threat are detected as Wimad. Gecedoc then searches your hard drive for clean media files with the following extensions:

  • .asf
  • .mp2
  • .mp3
  • .wma
  • .wmv

If found, the malware alters the file to run a malicious URL script command.

Payload

Downloads arbitrary files  

TrojanDownloader:ASX/Wimad may download arbitrary files, and employ social engineering techniques to assist the malware's execution (see the description for TrojanClicker:ASX/Wimad.CX for details of how social engineering may be used). The following servers have been observed to be contacted for these purposes:

  • 10yearsmusic.com
  • 193.138.172.14
  • 216.93.188.81
  • 68.178.225.162
  • 85.17.138.60
  • 85.17.93.189
  • ad.winadclient.com
  • adult.pornparks.com
  • americansexonline.com
  • calyeung.com
  • coolpixhost.biz
  • cxgr.com
  • dabao1.cn
  • darixo.com
  • drm.ysbweb.com
  • e-mirrorsite.com
  • fastmp3player.com
  • flashupd.com
  • free.f2player.com
  • freeaudiocodecs.com
  • friskypotato.com
  • funsiteshere.com
  • go.galaplayer.com
  • goodtimesplayer.com
  • goodtimesplayer.com
  • hasvideo.net
  • hotstuffbox.com
  • installation1.radmp3player.com
  • isvbr.net
  • license.mediapassonline.com
  • lost.to/in.cgi?8
  • media.downloadmediacentral.com
  • media.licenseacquisition.org
  • mediaprovider.info
  • microsoftmedicenter.com
  • minisites.mypengo.com
  • missing-codecs.com
  • mp.profittrol.com
  • mp3codec.info
  • mp3codecdownload.com
  • mpegcodecupdate.com
  • msdomains.org
  • myfirstsexteacher.com
  • network.adsmarket.com
  • nms.whenu.com
  • now.divocodec.com
  • peertracking.com
  • pinballpublishernetwork.com
  • playmoviesx.com
  • playstream.searchasong.net
  • pluginprovider.com
  • primeroute.net
  • profittable.com
  • purefunland.com
  • radarixo.com
  • realcodec.com
  • realsexsites.com
  • redirsystem32.com
  • remarkablesongslive.com
  • remarkablesongslive.com
  • sameshitasiteverwas.com
  • selectusers.com
  • sexnyu.com
  • sexygirlsluts.com
  • sharebuddy.ourtoolbar.com
  • somegreatsongs.com
  • spweb.whenu.com
  • surf.to/mp3galaxy
  • tpbtrack.com
  • tvcodec.net
  • upgradecodec.cinedump.com
  • uwww.exitforcash.com
  • vidareal2010.pisem.su
  • vidscentral.net
  • winbutler.com
  • winmediapackage.com
  • wonderfultracks.com

In the wild, we have observed the following files being loaded onto a users computer following successful exploitation of one of the aforementioned social engineering techniques:

  • access.exe
  • asf_codec.exe
  • Codec.exe
  • codec_update2.7.exe
  • mp3_codec_update.exe
  • mp3codec.exe
  • PLAY.exe
  • Play_mp3.exe
  • SecureInstall_LOFS020701Inst.exe
  • security-update-KB964085.exe
  • setupe.exe
  • Windows_Media_Player_Flash_Codec_Plugin.exe
  • windows_media_update.exe

Downloads malicious and potentially unwanted programs

In the wild, we have observed variants of TrojanDownloader:ASX/Wimad downloading the following malicious and potentially unwanted programs:

 

Redirects web browser

Variants of TrojanDownloader:ASX/Wimad may redirect the affected user's web browser to the following:

  • Phishing websites
  • Adult content websites
  • Advertisements
Additional information

The Advanced Systems Format (ASF) is the file format used by Windows Media. Audio and/or video content compressed with a wide variety of codecs can be stored in an ASF file and played back with the Windows Media Player (provided the appropriate codecs are installed), streamed with Windows Media Services or optionally packaged with Windows Media Rights Manager.For more information, refer to the Advanced Systems Format (ASF) specification here: http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=14995

Further reading

Analysis by Methusela Cebrian Ferrer


Symptoms

There are no common symptoms associated with this threat. Alert notifications from installed antivirus software may be the only symptoms.

Prevention

Take the following steps to help prevent infection on your computer:
  • Enable a firewall on your computer.
  • Get the latest computer updates for all your installed software.
  • Use up-to-date antivirus software.
  • Limit user privileges on the computer.
  • Use caution when opening attachments and accepting file transfers.
  • Use caution when clicking on links to webpages.
  • Avoid downloading pirated software.
  • Protect yourself against social engineering attacks.
  • Use strong passwords.
Enable a firewall on your computer

Use a third-party firewall product or turn on the Microsoft Windows Internet Connection Firewall.

Get the latest computer updates

Updates help protect your computer from viruses, worms, and other threats as they are discovered. It is important to install updates for all the software that is installed in your computer. These are usually available from vendor websites. Instructions on how to download the latest versions of some common software is available from the following:

You can use the Automatic Updates feature in Windows to automatically download future Microsoft security updates while your computer is on and connected to the Internet.

Use up-to-date antivirus software

Most antivirus software can detect and prevent infection by known malicious software. To help protect you from infection, you should always run antivirus software, such as Microsoft Security Essentials, that is updated with the latest signature files. For more information, see http://www.microsoft.com/windows/antivirus-partners/.

Limit user privileges on the computer

Starting with Windows Vista and Windows 7, Microsoft introduced User Account Control (UAC), which, when enabled, allowed users to run with least user privileges. This scenario limits the possibility of attacks by malware and other threats that require administrative privileges to run.

You can configure UAC in your computer to meet your preferences:

Use caution when opening attachments and accepting file transfers

Exercise caution with email and attachments received from unknown sources, or received unexpectedly from known sources. Use extreme caution when accepting file transfers from known or unknown sources.

Use caution when clicking on links to webpages

Exercise caution with links to webpages that you receive from unknown sources, especially if the links are to a webpage that you are not familiar with, unsure of the destination of, or suspicious of. Malicious software may be installed in your computer simply by visiting a webpage with harmful content.

Avoid downloading pirated software

Threats may also be bundled with software and files that are available for download on various torrent sites. Downloading "cracked" or "pirated" software from these sites carries not only the risk of being infected with malware, but is also illegal. For more information, see 'The risks of obtaining and using pirated software'.

Protect yourself from social engineering attacks

While attackers may attempt to exploit vulnerabilities in hardware or software to compromise a computer, they also attempt to exploit vulnerabilities in human behavior to do the same. When an attacker attempts to take advantage of human behavior to persuade the affected user to perform an action of the attacker's choice, it is known as 'social engineering'. Essentially, social engineering is an attack against the human interface of the targeted computer. For more information, see 'What is social engineering?'.

Use strong passwords

Attackers may try to gain access to your Windows account by guessing your password. It is therefore important that you use a strong password – one that cannot be easily guessed by an attacker. A strong password is one that has at least eight characters, and combines letters, numbers, and symbols. For more information, see http://www.microsoft.com/protect/yourself/password/create.mspx.


Alert level: Severe
This entry was first published on: Nov 22, 2011
This entry was updated on: Nov 30, 2011

This threat is also detected as:
No known aliases