W32.Cblade.Worm

SUMMARY

W32.Cblade.Worm is a Microsoft SQL Server worm that infects only computers on which SQL Server is installed and which have the default installation where the Administrator account has no password.

Behavior

Symptoms

Transmission

Protection

• Virus Definitions (Intelligent Updater) November 24, 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

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

Microsoft SQL Server is vulnerable if it has the default installation where the Administrator account has no password. It uses this vulnerability to send itself to other vulnerable Microsoft SQL Servers.

When it is executed, W32.Cblade.Worm does the following:

It calls xp_cmdshell, which enables the worm to run DOS commands directly from SQL Server. This permits the worm to run xp_cmdshell and to remotely execute commands on other SQL Servers.

It uses FTP to connect to an FTP server at the IP address 207.29.192.160.

The worm then logs in as:

User: ftp
Password: foo.com

Next, the worm attempts to use the FTP "get" command to download the file Dnsservice.exe. (The Dnsservice.exe file is the worm itself.) It then attempts to execute Dnsservice.exe. (At this time, the Dnsservice.exe file has been removed from the FTP site.)

The worm also attempts to connect to an IRC server and send information about the compromised system, such as the IP address of the computer. This could allow a hacker to quickly discover the system and attempt to upload other Trojans, such as backdoors. This is only possible if the Administrator account has no password.

The worm also adds the value

TaskReg

to the registry key

HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun

so that the worm runs when you start Windows.

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 worm, delete files detected as W32.Cblade.Worm and remove the value that it added to the registry.

To remove the worm:

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
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 W32.Cblade.Worm.

To edit the registry:

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

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_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
4. In the right pane, delete the following value:
   
   TaskReg
   
5. Exit the Registry Editor.