Backdoor.LoxoScam

SUMMARY

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

Protection

• Virus Definitions (LiveUpdate™ Weekly) November 24, 2002
• Virus Definitions (Intelligent Updater) November 22, 2002

TECHNICAL DETAILS

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:WindowsSystem (Windows 95/98/Me), C:WinntSystem32 (Windows NT/2000), or C:WindowsSystem32 (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~1Micros~1OfficeFindfast.exe with the file Exec.hlp. The original Rundll.exe is copied as C:WindowsSystemDis.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_MACHINESoftwareMicrosoftWindowsCurrentVersionRunService

It modifies the value from

LoadPowerProfile Rundll32.exe powerprof.dll,LoadCurrentPwrScheme

to

LoadPowerProfile Rundll.exe powerprof.dll,LoadCurrentPwrScheme

in the registry key

HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun

and

HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunService

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":

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• 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.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. 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.

REMOVAL

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.
   • Norton AntiVirus consumer products: Read the document How to configure Norton AntiVirus to scan all files.
   • Symantec enterprise antivirus products: Read the document How to verify a Symantec Corporate antivirus product is set 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:WindowsSystemDis.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_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRunServices
   
4. In the right pane, delete the value
   
   SystemDll  %windir%SystemDll.exe
   
5. In both of these keys:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunService
   
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:WindowsRecent 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:WindowsRecent, 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
   
   %windirSys.bat
   
4. Click File, and click Save.
5. Click File, and click Exit.