Backdoor.Hitcap

SUMMARY

Backdoor.Hitcap is a Backdoor Trojan that gives an attacker unauthorized access to your computer.

Backdoor.Hitcap consists of two components

1. An executable file: The executable file is packed with ASPack v1.06.
2. A .dll file: The .dll file is packed with PECompact v1.50.

Security Response has received several submissions of Backdoor.Hitcap, which were distributed in the form of an email message with a viral VBScript. Symantec antivirus products detect the script that drops Backdoor.Hitcap as Trojan dropper or Trojan.Downloader.Inor.

Protection

• Virus Definitions (LiveUpdate™ Weekly) February 19, 2003
• Virus Definitions (Intelligent Updater) February 18, 2003

Threat Assessment

Wild

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

Damage

• Damage Level: Medium
• Modifies Files: Modifies the system registry
• Compromises Security Settings: Allows unauthorized access to the compromised machine

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

Executable file
When the Backdoor.Hitcap executible file is run, it performs the following actions:

1. Creates the file %System%Thrh1032.dll. This .dll file is carried by the executable file in its resource. Thrh1032.dll is detected as Backdoor.Hitcap.
   
   NOTE: %System% is a variable. The Trojan locates the System folder and creates the file in that location. By default, this is C:WindowsSystem (Windows 95/98/Me), C:WinntSystem32 (Windows NT/2000), or C:WindowsSystem32 (Windows XP).
   
2. Creates the following values:
   
   chk0
   chs1
   chs2
   chsA
   cht0
   cls1
   cls2
   cls3
   cls4
   cnk9
   
   in the registry key:
   
   HKEY_CURRENT_USERSoftwareINTELVIDEOCHIP
   
   The Trojan uses these values to store its internal information in an encoded form.
   
3. Sets the viral .dll file to run when you start Windows, by adding these values:
   
   ThreadingModel     Apartment
   (Default)   %System%Thrh1032.dll
   
   to the registry key:
   
   HKEY_CURRENT_USERSoftwareClassesCLSID
   {10193F30-1559-6F09-051B-700B2B614800}InProcServer32
   
   and the value:
   
   Windows Development Features    {10193F30-1559-6F09-051B-700B2B614800}
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows
   CurrentVersionShellServiceObjectDelayLoad
   
4. Loads Thrh1032.dl by running Rundll32.exe and passing the viral .dll file as a parameter.

Viral .dll
When the Viral .dll is loaded, it performs the following actions:

1. Creates the "ThirdReich10" mutex. This mutex allows only one instance of Backdoor.Hitcap to execute in memory.
2. Connects to an IRC server, joins a specific channel, and notifies a hacker by sending a private message.
3. Waits for commands from the remote client. The commands allow the hacker to perform any of the following actions:
   • Deliver system information to the hacker
   • Download files
   • Execute files

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

These instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

1. Update the virus definitions.
2. Restart the computer in Safe mode.
3. Reverse the changes that the Trojan made to the registry.
4. Run a full system scan and delete all the files detected as Backdoor.Hitcap, Trojan dropper, or Trojan.Downloader.Inor.

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

1. 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.

2. Restarting the computer in Safe mode
All the Windows 32-bit operating systems, except Windows NT, can be restarted in Safe mode. For instructions on how to do this, read the document, "How to start the computer in Safe Mode."


3. Reversing the changes 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 the specified keys only. Read the document, "How to make a backup of the Windows registry," for instructions.

1. Click Start, and then click Run. (The Run dialog box appears.)
2. Type regedit
   
   Then click OK. (The Registry Editor opens.)
   
3. Navigate to the key:
   
   HKEY_CURRENT_USERSoftwareINTELVIDEOCHIP
   
4. In the right pane, delete these values:
   
   chk0
   chs1
   chs2
   chsA
   cht0
   cls1
   cls2
   cls3
   cls4
   cnk9
   
5. Navigate to and delete the following key:
   
   HKEY_CURRENT_USERSoftwareClassesCLSID
   {10193F30-1559-6F09-051B-700B2B614800}
   
6. Navigate to the following key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows
   CurrentVersionShellServiceObjectDelayLoad
   
7. In the right pane, delete the following value:
   
   Windows Development Features    {10193F30-1559-6F09-051B-700B2B614800}
   
8. Exit the Registry Editor.

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.Hitcap, Trojan dropper, or Trojan.Downloader.Inor, click Delete.