1. Symantec/
  2. Security Response/
  3. W32.Yimfoca


Risk Level 1: Very Low

May 2, 2010
April 23, 2012 4:38:25 AM
Also Known As:
Troj/PushBot-U [Sophos]
Infection Length:
Systems Affected:
When executed, the worm copies itself as the following file:

It then attempts to copy the following file to the %Windir%, %UserProfile%\Public, or %ProgramFiles% folder, whichever it successfully copies to first:
[FOLDER NAME]\nvsvc32.exe

It also creates the following files:
  • %Windir%\mds.sys
  • %Windir%\mdt.sys
  • %Windir%\mdl.dl
  • %Windir%\winbrd.jpg
  • %Windir%\winbrd.png
  • %Windir%\winbrfy.jpg

It then creates the following registry entry so that it runs every time Windows starts:
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\"Firewall Administrating" = "%Windir%\infocard.exe"
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\NVIDIA driver monitor: "[FOLDER NAME]\nvsvc32.exe"
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\NVIDIA driver monitor: "[FOLDER NAME]\nvsvc32.exe"

The worm will also create the following registry entries in order to bypass the Windows Firewall:
  • HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List\"[FOLDER NAME]\nvsvc32.exe" = "[FOLDER NAME]\nvsvc32.exe:*:Enabled:NVIDIA driver monitor"
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List\"[FOLDER NAME]\nvsvc32.exe" = "[FOLDER NAME]\nvsvc32.exe:*:Enabled:NVIDIA driver monitor"

It also modifies the following registry entry, changing the Internet Explorer home page:
HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\"Start Page" = "http://redirecturls.info"

Note: The worm will reset the home page to this URL every 30 minutes.

Next, the worm attempts to connect to the following URL:

The worm then stops the following processes to disable the Microsoft Malware Protection Service and Windows Update:
  • MsMpSvc
  • wuauserv

It then attempts to connect to the following URL to download a configuration file:

The worm may also download other files on to the compromised computer, which may be copies of other malware.

It connects to the following network addresses on TCP port 2345 and waits for IRC commands:
  • e2doo.org
  • sls.e2doo.net

It may also connect to one of the following URLs:
  • [http://]screenservice.com/inde[REMOVED]
  • [http://]jb.asm.org/inde[REMOVED]
  • [http://]scribbidyscrubs.com/inde[REMOVED]
  • [http://]tripadvisor.com/inde[REMOVED]
  • [http://]journals.lww.com/inde[REMOVED]
  • [http://]erdbeerlounge.de/inde[REMOVED]
  • [http://]heidegger.x-y.net/inde[REMOVED]
  • [http://]middleastpost.org/inde[REMOVED]
  • [http://]mcsp.lvengine.com/inde[REMOVED]
  • [http://]versatek.com/inde[REMOVED]
  • [http://]astro.ic.ac.uk/inde[REMOVED]
  • [http://]goodreads.com/inde[REMOVED]
  • [http://]albertoshistory.info/inde[REMOVED]
  • [http://]stayontime.info/inde[REMOVED]
  • [http://]websitetrafficspy.com/inde[REMOVED]
  • [http://]southampton.ac.uk/inde[REMOVED]
  • [http://]refugee-action.org.uk/inde[REMOVED]
  • [http://]unclefed.com/inde[REMOVED]
  • [http://]transnationale.org/inde[REMOVED]
  • [http://]journalofaccountancy.com/inde[REMOVED]
  • [http://]summer-uni-sw.eesp.ch/inde[REMOVED]
  • [http://]www.shearman.com/inde[REMOVED]
  • [http://]shopstyle.com/inde[REMOVED]
  • [http://]deirdremccloskey.org/inde[REMOVED]
  • [http://]hrm.uh.edu/inde[REMOVED]
  • [http://]insidehighered.com/inde[REMOVED]
  • [http://]mix.thenaturistclub.com/inde[REMOVED]
  • [http://]ate.lacoctelera.net/inde[REMOVED]
  • [http://]xxx.stopklatka.pl/inde[REMOVED]
  • [http://]mas.univie.ac.at/inde[REMOVED]
  • [http://]opl.munin.irf.se/inde[REMOVED]
  • [http://]mas.0730ip.com/inde[REMOVED]
  • [http://]mas.ahlamontada.com/inde[REMOVED]
  • [http://]xxx.jagdcom.de/inde[REMOVED]
  • [http://]old.longjuyt2tugas.com/inde[REMOVED]
  • [http://]mmm.bolbalatrust.org/inde[REMOVED]
  • [http://]mix.price-erotske.in.rs/inde[REMOVED]
  • [http://]mas.juegosbakugan.net/inde[REMOVED]
  • [http://]qun.51.com/inde[REMOVED]
  • [http://]epp.gunmablog.jp/inde[REMOVED]
  • [http://]old.youku.com/inde[REMOVED]
  • [http://]mas.tguia.cl/inde[REMOVED]
  • [http://]ope.oaklandathletics.com/inde[REMOVED]
  • [http://]beta.neogen.ro/inde[REMOVED]
  • [http://]ale.pakibili.com/inde[REMOVED]
  • [http://]mas.mtime.com/inde[REMOVED]
  • [http://]pru.landmines.org/inde[REMOVED]
  • [http://]uks.linkedin.com/inde[REMOVED]
  • [http://]mas.josbank.com/inde[REMOVED]
  • [http://]mas.archivum.info/inde[REMOVED]
  • [http://]ols.systemofadown.com/inde[REMOVED]
  • [http://]pra.aps.org/inde[REMOVED]

Next, the worm searches windows on the compromised computer for those that belong to Yahoo! Messenger.

The worm spreads by sending messages that contain links to copies of the worm to all Yahoo! Messenger contacts.

The following messages may be sent by the worm:
  • foto :D [http://]tusfbfotos.com/imag[REMOVED]
  • foto :D [http://]kompnk.com/imag[REMOVED]
  • foto :D [http://]beautyphotoson.com/imag[REMOVED]

The worm will prompt users to fill out surveys in order to gain access to popular sites such as facebook.com, if they are using Internet Explorer. The user will be unable to log into his or her account until a survey is completed. Survey messages include the following:
  • You have only 3 minutes to fill out the selected survey or you will be banned from this site.
  • Complete one of these surveys to gain access this page. Otherwise you will not have access to this page.

If the following strings are typed into the Internet Explorer address bar, further surveys may be displayed or the browser will be closed:
  • vagina
  • bick
  • fuck
  • XXX
  • virus
  • hardcore
  • drug
  • sexua
  • porn
  • register
  • r.php
  • login
  • cpa
  • facebook
  • cpa
  • lead
  • google
  • bing
  • yahoo
  • live
  • mail
  • microsoft
  • window
  • aricles
  • vidr
  • ruch
  • porn
  • sex
  • tube
  • adult
  • gllo
  • xnxx
  • xvideos
  • kyarticl
  • lmsarchiv
  • rticleslo
  • fuck
  • afemo
  • fullarti
  • i24searc
  • article
  • kanaa
  • enthou
  • iggarti
  • virus
  • myspace
  • postart
  • perbizsear
  • m-new
  • cpalead
  • freeart
  • astmo
  • cpa
  • lead
  • outu
  • daddie
  • porn
  • gay
  • adobe
  • geshac


Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.
Writeup By: Mircea Ciubotariu
Summary| Technical Details| Removal

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