W97M.Ping.A | 
|
The W97M.Ping.A virus is a macro virus. The macro virus works in Microsoft Word 97 and potential later versions. This macro virus infects the This Document module inside of Microsoft Word 97 such that you may not see an additional macro under Tools | Macro | Macro like traditional macro viruses. Other than replicating, the W97M.Ping.A virus will attempt to ping four different hosts indefinitely potentially causing a denial of service and network congestion.
The W97M.Ping.A virus replicates when opening an infected document. First, W97M.Ping.A will deactivate the macro virus protection feature in Microsoft Word 97. This feature prompts you when opening a document with macros.
Next, the virus checks to see if the document or global template is already infected. The virus does this with a simple infection length check. If the length of the module exceeds the length of the virus, the virus assumes it is already infected. Thus, the virus may not infect all documents or templates.
If the document or template is not already infected, the virus copies itself into the This Document module. After successfully replicating itself, the virus then executes its payload.
The payload pings four different hosts. The pings are executed indefinitely with a static buffer size. These pings can cause network congestion and a denial of service.
Norton AntiVirus will repair by removing all the code in the This Document module.
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.
Norton AntiVirus users can protect themselves from this virus by downloading the current virus definitions either through LiveUpdate or from the following webpage:
http://www.symantec.com/avcenter/download.html
Write-up by: Eric Chien
|
