Backdoor.RemoteSOB

SUMMARY

The Backdoor.RemoteSOB Backdoor Trojan allows unauthorized access to the infected computer. By default, it attempts to listen on port 7,811 and use ICQ to notify the hacker.

This threat is written in the Delphi programming language and is compressed with UPX. The uncompressed size is approximately 885 KB.

Protection

• Virus Definitions (LiveUpdate™ Weekly) January 15, 2003
• Virus Definitions (Intelligent Updater) January 8, 2003

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

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When Backdoor.RemoteSOB is executed, it does the following:

1. Copies itself as %Windir%Bdsf32.scr.
   
   NOTE: %Windir% is a variable. The Trojan locates the Windows installation folder (by default, this is C:Windows or C:Winnt) and copies itself to that location.
   
2. Changes the shell= line in the System.ini file to:
   
   Explorer.exe %Windir%Bdsf32.scr
   
   so that the Trojan runs when you start Windows on Windows 95/98/Me computers.
   
3. Waits for commands from the hacker to perform the following actions:
   • Open or close the CD-ROM drive
   • Logoff, restart, or shut down Windows
   • Swap or restore the mouse button
   • Cause the computer to beep
   • Obtain the Windows logon user name
   • Shut down the Trojan
   • List or create folders
   • Download files from the Internet
   • Delete, rename, execute, or read files
   • Open Web pages
   • Run DOS commands
   • Print data

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. Edit the System.ini file and remove the text added by the Trojan (Windows 95/98/Me only).
2. Update the virus definitions.
3. Run a full system scan and delete all the files detected as Backdoor.RemoteSOB.
   
   

For specific details on each of these procedures, read the following instructions.

1. Editing the System.ini file
If you are using Windows NT/2000/XP, this is not necessary. Go to section 2.

1. Click Start, and then click Run. (The Run dialog box appears.)
2. Type Notepad C:WindowsSystem.ini, and then click OK. (The Notepad windows opens.)
   
   NOTE: If you have Windows installed at a different location, modify the path and folder names as necessary.
   
3. In the [boot] section of the file, look for an entry similar to the following:
   
   Shell=Explorer.exe C:Windowsdsf32.scr
   
4. Delete all the text (on the shell=Explorer.exe line only) to the right of Explorer.exe. When you are finished, the text should like:
   
   Shell=Explorer.exe
   
5. Click File, click Exit, and then click Yes when prompted to save the changes.

2. Updating the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:

• Running LiveUpdate, which is the easiest way to obtain the virus definitions. These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate), in the "Protection" section, at the top of this writeup.
• Downloading the definitions using the Intelligent Updater. The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater), in the "Protection" section, at the top of this writeup.
  
  The 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.

3. Scanning for and deleting the infected files

1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
   • For Norton AntiVirus consumer products: Read the document, "How to configure Norton AntiVirus to scan all files."
   • For Symantec AntiVirus Enterprise products: Read the document, "How to verify that 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.RemoteSOB, click Delete.