W97M.Cali.A

W97M.Cali.A is a macro virus. This MS Word 97 macro virus will add a VBA module called "Caligula" into infected document/template.

Also Known As:	W97M/Caligula
Type:	Macro
Infection Length:	1 VBA Module

Wild Number of infections: 0 - 49 Number of sites: 0 - 2 Geographical distribution: Low Threat containment: Easy Removal: Easy

Threat Metrics Wild: Low Damage: Low Distribution: Low

Damage

• Payload: 1. While closing an infected document, the virus, modifies the following File Summary Information fields: · Author = "Opic" · Title = "WM97/Caligula Infection" · Subject = "A Study In Espionage Enabled Viruses." · Comments = "The Best Security Is Knowing The Other Guy Hasn't Got Any." · Keywords = " | Caligula | Opic | CodeBreakers | " File Summary Information is accessible from File-Properties menu in MS Word 97. 2. The second payload demonstrates the growing trend of virus writer to use the Internet connectivity for a virus' payload. While closing an infected document, the virus search for Pretty Good Privacy (PGP) secret key ring file (SECRING.SKR) if PGP is installed. If it finds this file, it tries to upload this file into the ftp site of the virus's author. While uploading the file, the virus creates a temporary text file "C:\CDBRK.VXD" The virus marks a successful upload in a boolean entry "Caligula" in the following Win95 registry key: HKEY_CURRENT_USER\Software\Microsoft\MS Setup (ACME)\User Info Thus, it will only do this process once. Although this could give the virus author access to a user PGP Secret Key Ring file, the virus author still needs the user's PGP password to decrypt a PGP-encrypted file sent to the user, and only if the virus author can get the encrypted file in the first place. Moreover, one can always creates a new PGP Secret Key Ring file
  • Modifies files: Normal.dot

Distribution

• Target of infection: MS Word 97 document

While infecting a document or global template, this macro virus uses a temporary text file "C:\IO.VXD"

This macro virus tries to hide itself (stealth) by disabling the following menu:
· File-Template
· Tools-Customize
· Tools-Macro
· Tools-Macro-VisualBasicEditor
· View-Toolbars
· View-Status-bar

By disabling these menu command, the virus prevents any user from listing the macro / VBA module in a document to check for infection.

To hide its infection activity, it also disables the following options:

With these options disabled, MS Word 97 will not display a warning that the document contains macros or prompt when saving the NORMAL.DOT when opening a document with macros in it.

While closing an infected document on the 31st of any month, it displays a message box entitled "WM97/Caligula (c) Opic [CodeBreakers 1998]" :

No cia,

No nsa,

No satellite,

Could map our veins.

This virus was submitted to the Symantec AntiVirus Research Center on January 21, 1999 through Norton Anti-Virus Scan-and-Deliver system.

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.

Although the temporary text file "C:\IO.VXD" and "C:\CDBRK.VXD" itself created by the virus are harmless, deleting them manually is recommended.

The Word’s options and menu-commands altered by the virus can be restored by deleting NORMAL.DOT. Word will automatically create a new NORMAL.DOT when it is launched.

Write-up by: Raul K. Elnitiarta