W97M.Marker

W97M.Marker is a common macro virus with a unique payload. Similar to W97M.Class, it adds its viral code to the "ThisDocument" VBA5 module, which by default is always in Microsoft Word 97 documents and templates. It also uses a randomly-named temporary text file while infecting. The random name is HSFxxxx.sys where xxxx is a randomly-generated number.

Type: Macro, Virus

Infection Length: one VBA5 module

Wild

Threat Metrics

Wild: Low	Damage: Low	Distribution: Low

W97M.Marker will keep a log of the date and time of the infection, as well as the registered user information from Microsoft Word. When the payload in this virus activates on the 1st of each month, it will attempt to upload this information to an FTP site. It will only upload the information once. The virus tracks or marks the uploading through the LogFile value in the registry key:
HKEY_CURRENT_USER\Software\Microsoft\ MS Setup (ACME)\User Info

NOTE: This key is a common registry entry that is created by many Microsoft program setup routines.

The Value data of LogFile" is set to TRUE if the virus has successfully uploaded the user information (name and address) to the FTP site. Once the value is TRUE, the virus does not attempt another upload of the user information.

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.

To remove this virus:

Run LiveUpdate to make sure that you have the most recent virus definitions.
Start Norton AntiVirus (NAV), and then run a full system scan, making sure that NAV is set to scan all files.
If any files are detected as infected by W97M.Marker, choose Repair.
(Optional). This macro virus uses a temporary text file, C:\Netldx.vxd while executing its payload routine, and the file HSFxxxx.sys (where xxxx is a randomly-generated number) while executing its infection routine. You can delete these text files if desired, although leaving them will no do any damage.
(Optional) Delete the LogFile value from the registry key:

HKEY_CURRENT_USER\Software\Microsoft\ MS Setup (ACME)\User Info

NOTE: Leaving it there will not cause any harm. In fact, if it's already set to TRUE, it will prevent the uploading of the user information (name and address).

Write-up by: Jennifer Hirons