W32.Fusic@mm

SUMMARY

W32.Fusic@mm is a mass-mailing worm with backdoor capabilities that replicates by email. It uses MAPI to send itself to the contacts in the Windows Address Book. The email message has the following (randomly chosen) characteristics :

Subject: To be my friend?
Message Body: To be my friend?Please look at my photos in the attachment
Attachment: My introduction and photos.exe

Subject: resume
Message Body: Please look at my resume
Attachment: My resume.exe

Subject: Funny movie
Message Body: Funny flash movie
Attachment: Funny movie.exe

Subject: Document you want
Message Body: What you want is in the attachment
Attachment: Readme.exe

Protection

• Virus Definitions (LiveUpdate™ Weekly) November 28, 2002
• Virus Definitions (Intelligent Updater) November 22, 2002

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
• Modifies Files: Modifies system registry.
• Releases Confidential Info: Intercept confidential information by hooking any keystrokes.

Distribution

• Distribution Level: Medium
• Subject of Email: Variable
• Name of Attachment: Variable

TECHNICAL DETAILS

When W32.Fusic@mm runs, it performs the following actions:

It copies itself as %system%KernelKernel32.exe.

It creates the following files:

• %system%FuncDLL.dll
• %system%IEHelper.dll

NOTE: %system% is a variable. The worm 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).

Both .dll files are used by the Trojan component to intercept keystrokes. FuncDLL.dll can intercept keystrokes by hooking keyboard messages. IEHelper.dll can handling Internet Explorer events that are triggered by the browser whenever you enter data into input fields. Both file log intercepted data and the URL into %system%Passlogx.log. The presence of this file may indicate the infection, and you can, if needed, look at the file to determine what information was intercepted. Both .dll files are detected by Symantec antivirus products as PWS.Hooker.Trojan.

The worm creates the value

kernel    %system%kernelkernel32.exe

in the registry key

HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun

so that the worm starts when you start or restart Windows.

Also, it creates the following registry keys:

• HKEY_LOCAL_MACHINESOFTWAREkernel
• HKEY_LOCAL_MACHINESOFTWAREkernelA09b37xz

The keys contain values that store internal configuration data.

If the operating system is Windows 95/98/Me, the worm registers itself as a service process to continue to run after you log off. In this case, W32.Fusic@mm will close only when the system is shut down.

The worm installs hook procedures into a hook chain to monitor the system for any keyboard and mouse messages. The keyboard and mouse hook procedures process the messages and pass the hook information to the next hook procedure in the current hook chain. This permits W32.Fusic@mm to intercept any key strokes.

Once installed, W32.Fusic@mm waits for commands from the remote client. The commands allow the hacker to perform any of the following actions:

• Deliver system and network information to the hacker
• Terminate processes
• Intercept confidential information by hooking any keystrokes

The worm inventories contacts in the Windows Address Book and sends itself using MAPI. If it cannot locate the address book file, it tries to obtain the location of Wab32.dll. Then it loads that .dll and calls WABOpen() to open the Address Book.

Next, the worm checks the Locale ID.

If it is not Chinese (PRC), then the email message has the following randomly chosen characteristics:

Subject: To be my friend?
Message Body: To be my friend?Please look at my photos in the attachment
Attachment: My introduction and photos.exe

Subject: resume
Message Body: Please look at my resume
Attachment: My resume.exe

Subject: Funny movie
Message Body: Funny flash movie
Attachment: Funny movie.exe

Subject: Document you want
Message Body: What you want is in the attachment
Attachment: Readme.exe

It the Locale ID is Chinese (PRC), the messages are composed in Chinese.

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 W32.Fusic@mm.
3. Reverse the changes that the worm made to the registry.
   

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 W32.Fusic@mm, click Delete.

To delete the value from 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_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
4. In the right pane, delete the value
   
   kernel    %system%kernelkernel32.exe
   
5. Navigate to and then delete the following registry keys:
   
   HKEY_LOCAL_MACHINESOFTWAREkernel
   
   HKEY_LOCAL_MACHINESOFTWAREkernelA09b37xz
   
6. Exit the Registry Editor.