诺顿杀毒软件从2003年10月1日开始，对3721的广告说不！认定3721的广告为广告病毒，并提供杀除方法在诺顿的网站上，下面是摘录诺顿网站的内容，还有相关链接。不知道这对于各位网友是福是悲，3721是做得过分了，但是诺顿呢？我想他们两家可能会有一些协商吧，西部E网会追踪报道！

Type:	Adware
Systems Affected:	Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows Server 2003, Windows XP
Systems Not Affected:	DOS, Linux, Macintosh, OS/2, UNIX
Removal:	Low
Damage:	Low

Intelligent Updater Definitions* October 01, 2003 LiveUpdate™ Definitions ** October 01, 2003 * Intelligent Updater definitions are released daily, but require manual download and installation. Click here to download manually. ** LiveUpdate definitions are usually released every Wednesday. Click here for instructions on using LiveUpdate.

This threat can be detected only by Symantec products that support expanded threats. For more information on expanded threats, please go here.

Behavior
Adware.CNS3721 is an adware program that changes the Internet Explorer home page and contacts the Web site, cns.3721.com, for advertising purposes.

Symptoms
Your home page is changed to we.cn.gs.

Transmission
This adware component must be manually installed or installed as a component of another program that you install.

File names: Linmeimei.exe; Wupdate.exe

When Adware.CNS3721 is executed, it performs the following actions:

1. Copies itself to %System%\Wupdate.exe.
   
   

   ---

   Note: %System% is a variable. The worm locates the folder (by default, this is C:\Windows\System or C:\Winnt\System32) and copies itself to that location.

   ---

   
   
2. Adds the value:
   
   "Windows Update" =  %System%\Wupdate.exe
   
   to the registry key:
   
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
   
   so that the adware runs when you start Windows.
   
   
3. Changes the Internet Explorer home page to we.cn.gs.
   
   
4. Opens a browser window and displays a flash animation downloaded from the Internet.
   
   
5. May contact the Web site, cns.3721.com, for advertising purposes.
   
   
6. May download itself, or its updated version, from we.cn.gs.

• Running LiveUpdate, which is the easiest way to obtain virus definitions: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate).
• Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater).
  
  The Intelligent Updater virus definitions are available: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

1. Start Norton AntiVirus and make sure that it is configured to scan all the files. For more information, read the document, "How to configure Norton AntiVirus to scan all files."
2. Run a full system scan.
3. If any files are detected as infected with Adware.CNS3721, click Delete.
   
   

1. Click Start, and then click Run. (The Run dialog box appears.)
2. Type regedit
   
   Then click OK. (The Registry Editor opens.)
   
   
3. Navigate to the key:
   
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
   
   
4. In the right pane, delete any values pertaining to "Windows Update"
   
   
5. Exit the Registry Editor.

1. Start Microsoft Internet Explorer.
2. Connect to the Internet and go to the page that you want to set as your home page.
3. Click Tools > Internet Options.
4. In the Home page section of the General tab, click Use Current >OK.
5. On the Programs tab, click Reset Web Settings.

Write-up by: Tony Lee

原文请见：http://securityresponse.symantec.com/avcenter/venc/data/adware.cns3721.html

相关报道

金羊网-新快报：杀毒软件又错把3721当病毒 3721出面澄清

　　新快报讯 日前3721又险些被误认为是病毒。但后据3721方面表示，诺顿病毒清单中的并非为3721产品，仅仅是病毒名称中含有3721字眼，不会影响用户正常使用。

　　据了解，诺顿在10月1日诺顿公司列出了一长串的广告类病毒名单，其中第十五个“Adware.CNS3721File”可以弹出3721广告。但3721否认是该病毒文件的制造者。

　　记者了解到，1999年9月，3721也曾被诺顿认为含有病毒，使得用户在使用中文网址时，会频繁弹出病毒报警框。后来3721及时修改了相关的软件内容应变。