Backdoor.LoxoScam

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Discovered: November 22, 2002
Updated: February 13, 2007 11:50:51 AM
Also Known As: Backdoor.LoxoScam [AVP]
Type: Trojan Horse
Systems Affected: Windows


Backdoor.LoxoScam is a backdoor Trojan that allows a hacker to gain access to the computer. It is written in the Delphi programming language.

Antivirus Protection Dates

  • Initial Rapid Release version November 22, 2002
  • Latest Rapid Release version March 23, 2017 revision 037
  • Initial Daily Certified version November 22, 2002
  • Latest Daily Certified version March 23, 2017 revision 041
  • Initial Weekly Certified release date November 24, 2002

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Kaoru Hayashi

Discovered: November 22, 2002
Updated: February 13, 2007 11:50:51 AM
Also Known As: Backdoor.LoxoScam [AVP]
Type: Trojan Horse
Systems Affected: Windows


When Backdoor.LoxoScam runs, it does the following:

It drops these files:
%system%\ICQS.exe
%windir%\Exec.hlp
%windir%\SystemDll.exe
%windir%\R.exe
%windir%\Sys.bat

Exec.hlp, SystemDll.exe and R.exe are copies of the same file.

NOTES:

  • %windir% is a variable. The Trojan locates the Windows installation folder (by default this is C:\Windows or C:\Winnt) and copies the files to that location.
  • %system% is a variable. The Trojan locates the System folder and copies the files to that location. By default this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

It inserts this line in the Autoexec.bat file:

%windir%\sys.bat

The next time that you start Windows, on Windows 95/98/Me computers, the Sys.bat file is run. It attempts to replace %windir%\Rundll.exe and C:\Progra~1\Micros~1\Office\Findfast.exe with the file Exec.hlp. The original Rundll.exe is copied as C:\Windows\System\Dis.exe.

NOTE: The paths in Sys.bat file are static, so even it is run, it will not affect Windows NT/2000.

It adds the value

SystemDll  %windir%\SystemDll.exe

to the registry key

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunService

It modifies the value from

LoadPowerProfile Rundll32.exe powerprof.dll,LoadCurrentPwrScheme

to

LoadPowerProfile Rundll.exe powerprof.dll,LoadCurrentPwrScheme

in the registry key

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

and

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunService

so that the Trojan runs when you start Windows.

The Trojan opens TCP port to allow the hacker to remotely control the infected computer.

Recommendations

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: Kaoru Hayashi

Discovered: November 22, 2002
Updated: February 13, 2007 11:50:51 AM
Also Known As: Backdoor.LoxoScam [AVP]
Type: Trojan Horse
Systems Affected: Windows


NOTE: These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

  1. Update the virus definitions
  2. Run a full system scan, and delete all files that are detected as Backdoor.LoxoScam. Delete %system%\ICQS.exe and %windir%\Sys.bat if they exist.
  3. Restore Rundll.exe and Findfast.exe.
  4. Reverse the changes that it made to the registry.
  5. (Windows 95/98/Me) Remove the line that was added to the Autoexec.bat file.
For details on how to do this, read the following instructions.

To update the virus definitions:
All virus definitions receive full quality assurance testing by Symantec Security Response before being posted to our servers. There are two ways to obtain the most recent virus definitions:
  • Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions are posted to the LiveUpdate servers once each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
  • Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.

    Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.

To scan for and delete the infected files:
  1. Start your Symantec antivirus program, and make sure that it is configured to scan all files.
  2. Run a full system scan.
  3. If any files are detected as infected with Backdoor.LoxoScam, click Delete.
  4. Using Windows Explorer, delete %system%\ICQS.exe and %windir%\Sys.bat if they exist.


To restore Rundll.exe and Findfast.exe:
Using Windows Explorer, copy C:\Windows\System\Dis.exe to the Windows folder as Rundll.exe. If you use Findfast, you should reinstall it from the Microsoft Office installation disk.


To reverse the changes that it made to the registry:

CAUTION : Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.
  1. Click Start, and click Run. The Run dialog box appears.
  2. Type regedit and then click OK. The Registry Editor opens.
  3. Navigate to the key

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices
  4. In the right pane, delete the value

    SystemDll  %windir%\SystemDll.exe
  5. In both of these keys:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunService
  6. If the vlaue

    LoadPowerProfile Rundll.exe powerprof.dll,LoadCurrentPwrScheme

    exists, modiify it to

    LoadPowerProfile Rundll32.exe powerprof.dll,LoadCurrentPwrScheme
  7. Exit the Registry Editor.


To edit the Autoexec.bat file:

NOTE: (For Windows Me users only) Due to the file-protection process in Windows Me, a backup copy of the file that you are about to edit exists in the C:\Windows\Recent folder. Symantec recommends that you delete this file before you continue with the steps in this section. To do this using Windows Explorer, go to C:\Windows\Recent, and in the right pane select the Win.ini file and delete it. It will be regenerated as a copy of the file that you are about to edit when you save your changes to that file.
  1. Click Start, and click Run.
  2. Type the following, and then click OK.

    edit c:\autoexec.bat

    The MS-DOS Editor opens.
  3. Look for and delete the line

    %windir\Sys.bat
  4. Click File, and click Save.
  5. Click File, and click Exit.





Writeup By: Kaoru Hayashi