1. Symantec/
  2. Security Response/
  3. Trojan.Bankpatch.C


Risk Level 2: Low

August 18, 2008
February 3, 2009 6:11:43 PM
Infection Length:
Systems Affected:
When executed, the Trojan drops and executes one of the following files, which allows the Trojan to escalate its execution privileges:
  • %Temp%\conlf.ini
  • %Temp%\conlf[RANDOM DIGIT].ini

Next, it creates the following files:
  • %System%\kerndp.ini (Copy of kernel32.dll)
  • %System%\korlg.ini (Copy of kernel32.dll)
  • %System%\windmlp.ini (Copy of wininet.dll)
  • %System%\worlg.ini (Copy of wininet.dll)
  • %System%\ppdnp.ini (Copy of powrprof.dll)
  • %System%\pporgl.ini (Copy of powrprof.dll)

The Trojan then injects code into the following files:
  • %System%\kernel32.dll
  • %System%\powrprof.dll
  • %System%\wininet.dll

Note: The modified files are detected as Trojan.Bankpatch.C!Inf.

It also creates the following files:

The Trojan injects different code in to each infected .dll file.

Next, the Trojan modifies the following Windows APIs for %System%\kernel32.dll:
  • CreateFileW
  • CreateProcessInternalW

The Trojan modifies the following Windows APIs for %System%\powrprof.dll:
  • SetSuspendState
  • GetActivePwrScheme

It also modifies the following Windows APIs for %System%\wininet.dll:
  • HttpSendrequestA
  • HttpSendRequestW
  • InternetConnectA
  • InternetCrackUrlA

The threat creates the following file, that contains an encrypted version of the Trojan executable:

Next, it creates the following registry entries in order to save its configuration:
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\InternetSettings\"lwh" = "http://[FOUR LETTERS]anta.com"
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\"BEC" = [TWO DIGIT NUMBER]
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\"w8" = [COUNTRY]_[UID_LETTERS]
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\"ins" = "ins"

It may also create the following registry subkeys in order to save configuration data:
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\InternetSettings\rbt
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\hst
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\task

The Trojan attempts to run the following command in order to uninstall JAVA on the computer:
cmd.exe /c javasw -uninstall

The Trojan attempts to restart the computer after a certain period of time in order to become active in memory.

When the the computer restarts, the threat monitors the browser for certain banking-related URLs.

It then gathers the information and sends it to a remote Web server.

The Trojan then attempts to retrieve and verify the home page of google.com in order to verify network connectivity.

It then attempts to contact one of the following locations:
  • http://qmkaanta.com
  • http://meiwrsa.com
  • http://sqvnanta.com
  • http://trabanta.com
  • http://jtlqanta.com
  • http://kqbzanta.com

If one of the above domains is not conected to a network, it generates another domain name of the following format using a custom algorithm:
http://[FOUR LETTERS]anta.com

The Trojan sends the following request to the remote server:
http://[FOUR LETTERS]anta.com/index.php?id=[COUNTRY]_[UID_LETTERS]&check=[CMD]&version=[TROJAN VERSION NUMBER]

It stores the gathered information in the following folders:
  • %System%\dtw5d
  • %System%\cks

It also searches for the following browser plugins when Internet Explorer starts:
  • JAVA
  • e-Safekey
  • EBJSecurity_3

It creates the following registry subkeys in order to download more components on to the computer:
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\task\[DIGITS]\GUID
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\task\[DIGITS]\FROM
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\task\[DIGITS]\UPD

It downloads the following files and registers them as Browser Helper Objects (BHO):

It then creates the following registry subkeys in order to register the malicious BHO:
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\AppID\{3F0BD180-84B7-4AB5-873A-002217BD0CCE}
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{D527BCFE-9D2E-45E4-B32F-1658FEB581BF}
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{91F524EA-CD52-4437-A9E4-6A3552DC44D3}
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{524B9634-8729-48A5-B451-E5BB7154F6E3}
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{0EF464BB-A75C-4075-B7A6-6D48D05E7644}
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects\{B782EDE4-CCB3-4E3E-981F-96C68116F38C}
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\linkreader.Lnkrdrbho
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\linkreader.Lnkrdrbho.1

It may also download the following file, which is an update of the Trojan:

The Trojan may decrypt the original %System%\ldupdt.old file in order to prevent the Trojan from being deleted.

It may then run the file from the following location:


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: Elia Florio and Paul Mangan
Summary| Technical Details| Removal

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