Backdoor.Intruzzo

SUMMARY

Backdoor.Intruzzo is a remote access Trojan that was coded using Visual Basic 5.0; it consists of server and client components. The server component resides on a host computer; the client component is used by a hacker or group of hackers to manipulate the host computer.

The control over the host is comparable to other remote access Trojans such as Back Orifice.

TECHNICAL DETAILS

This remote access Trojan requires the following files in order to operate successfully on a host system:

• Msvbvm50.dll
• Comctl32.ocx
• Mswinsck.ocx

The server component may be received in email, or it can be sent manually by a hacker. It may even be distributed as part of a package of files or hosted on a hacker Web site. The executable for the server component can be any file name.

When the server component of the Trojan is first executed, it may display an icon of a man in an overcoat running from right to left across the screen as indicated in the following figure:



The icon continues to run across the screen until the dialog box is closed. The Trojan then copies itself to the system folder as GLIDELOAD.exe. To load the Trojan when Windows starts, the Trojan then adds the value

HPSFD %System%GLIDELOAD.exe /s

to the registry key

HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun

NOTE: %System% is a variable. The Trojan locates the WindowsSystem folder (by default this is C:WindowsSystem or C:WinntSystem32) and copies itself to that location.

The server component usually listens on TCP/IP port 22784. However, the port could be in the range 22783 - 22785.

The client component control screen is similar to the screen in the following figure:



The left display window shows the status of the client computer. The right window includes icons that correspond to the tasks that the Trojan can accomplish, such as ejecting the CD, controlling the mouse, and manipulating other system controls. The client program can also scan ports in search of computers on which the server component of the Trojan is installed.

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 the Trojan, scan with NAV, delete all infected files, and then remove the registry entry that the Trojan created.

To remove the Trojan:

1. Obtain the most recent virus definitions. There are two ways to do this:
   • Run LiveUpdate. LiveUpdate is the easiest way to obtain virus definitions. These virus definitions have undergone full quality assurance testing by Symantec Security Response and are posted to the LiveUpdate servers one time 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 have undergone full quality assurance testing by Symantec Security Response. They 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.
     
2. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files. For instructions on how to do this, read the document How to configure Norton AntiVirus to scan all files.
3. Run a full system scan.
4. Delete all files that are detected as Backdoor.Intruzzo.

To edit 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 following key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoft
   WindowsCurrentVersionRun
   
4. In the right pane, delete the following value:
   
   HPSFD %System%GLIDELOAD.exe /s
   
5. Click Registry, and click Exit.