Backdoor.Quimera

SUMMARY

Backdoor.Quimera is a Trojan horse that allows unauthorized access to your computer.

Protection

• Virus Definitions (Intelligent Updater) March 19, 2001

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Low
• Releases Confidential Info: Confidential information may be communicated without your knowledge
• Compromises Security Settings: Allows unauthorized access to your computer

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

Backdoor.Quimera is sent as an executable installation package. The executable file displays a Setup icon. When the file is run, it does the following:

1. It inserts the following files on the system:
   • C:~setup.tMswinsck.ocx
   • C:~setup.tTeste.exe
   • C:~setup.tVb40032.dll
     
2. After these files are extracted by the installer, Teste.exe is run. Teste.exe is a Visual Basic compiled executable that needs Vb40032.dll to run. The Mswinsck.ocx file is used to establish a connection over the Internet.
3. Teste.exe then registers the Mswinsck.ocx to the system, so that it is used when working with sockets.
4. Next, it adds the value
   
   modem1     C:WINDOWSNETCOM1.EXE
   
   to the following registry key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   This causes Netcom1.exe to be executed when Windows starts.
   
5. Teste.exe then inserts a copy of itself as C:WindowsNetcom1.exe, so that the added registry key can be executed.
6. Finally,it copies Vb40032.dll and Mswinsck.ocx from C:~setup.t to C:WindowsSystem.

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

To remove this Trojan, delete any files detected as Backdoor.Quimera and then remove the registry entry that was added by the Trojan.

To remove the files:

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and run a full system scan, making sure that NAV is set to scan all files.
3. Delete any files detected as Backdoor.Quimera.

To edit the registry:

CAUTION: We strongly recommend that you back up the system registry before making any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure you modify only the keys specified. Please see the document How to back up the Windows registry before proceeding.

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 following subkey:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
4. In the right pane, delete the following value:
   
   modem1     C:WINDOWSNETCOM1.EXE
   
5. Click Registry, and then click Exit to save the changes.