Description of Internet Explorer 3.0b/3.01b Security Update

ID: q165163

The information in this article applies to:

Microsoft Internet Explorer versions 3.0, 3.01 for Windows 95
Microsoft Internet Explorer versions 3.0, 3.01 for Windows NT 4.0

SUMMARY

Microsoft has released Internet Explorer versions 3.0b and 3.01b. This version is a comprehensive update that addresses several security issues in Internet Explorer versions 3.0 and 3.01 for Windows 95 and Windows NT 4.0. This version replaces the Internet Explorer 3.0a and 3.01a update that was released previously. If the version of Internet Explorer that you are using has been updated with the 3.0b or 3.01b patch, one of the following versions is reported when you click About Internet Explorer on the Help menu:

Version 3.0b (4.70.1155)
Version 3.0b (4.70.1158)
Version 3.01b (4.70.1215)

This article describes the problems that Internet Explorer 3.0b and 3.01b addresses, as well as the changes that it makes to your computer.

For more information about the availability of Internet Explorer security updates, see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q157923
   TITLE     : Internet Explorer Security Breach Patch Available

MORE INFORMATION

Fixes in Internet Explorer 3.0b and 3.01b

Internet Explorer 3.0b and 3.01b includes the following fixes:

3.0a/3.01a Security Update: Fix for the "Cybersnot" bug. This patch causes Internet Explorer to prompt you with the following warning when you open a Windows shortcut or link (.lnk) or Internet shortcut (.url):
```
      Opening:
      <file> from <server>
```
```
      Some files can contain viruses or otherwise be harmful to your
      computer. It is important to be certain that this file is from a
      trustworthy source. What would you like to do with this file?
```
You are then prompted to either open the file or save it to disk. Note that the "Always ask before opening this type of file" option is disabled when you are opening .lnk and .url file types as a result of the 3.0b/3.01b fix.
If you have installed the 3.0a/3.01a patch, you should upgrade to Internet Explorer 3.0b or 3.01b. To determine whether the version of Internet Explorer that you are using has been updated with the 3.0a/3.01a patch, click About Internet Explorer on the Help menu. One of the following versions is listed if you have updated to the 3.0a/3.01a patch:
```
    - Version 3.0a (470.1155)
    - Version 3.0a (470.1158)
    - Version 3.01a (4.70.1215)
```
A fix for the MIT variation of the "Cybersnot" bug that causes Internet Explorer to prompt you with the same warning as the "Cybersnot" bug when you open any of the following "unsafe" file types:
```
    - Executable file (.exe)
    - Zip file (.zip)
    - MS-DOS batch file (.bat)
    - MS-DOS program information file (.pif)
    - Setup information file (.inf)
    - Windows registry file (.reg)
    - Windows NT command script file (.cmd)
    - Qbasic file (.bas)
    - Internet shortcut (.url)
    - Internet link (.lnk)
    - MS-DOS program file (.com)
```
Note that the "Always ask before opening this type of file" option is disabled when you are opening any of the "unsafe" file types listed above as a result of the 3.0b/3.01b fix.
When you open any file that is not on the "unsafe" list, Internet Explorer prompts you with same warning, but you are able to enable or disable the "Always ask before opening this type of file" option.
A fix for the "UMD" bug that causes Internet Explorer to prompt you with the following warning when you open any file from a shell (folder) view within Internet Explorer:
```
      Some files can contain viruses or otherwise be harmful to your
      computer. It is important to be certain that this file is from a
      trustworthy source. Do you want to continue opening this file?
```
If you click OK, the file opens; if you click Cancel, the operation stops and the file is not opened or downloaded.
NOTE: This applies to "top-level browsing" using the Internet Explorer Address bar [that is, typing "C:\" or "\\<server>\<share>" (without quotation marks), where <server> is the computer and <share> is the folder or drive that contains the resources that you are accessing], or browsing local or remote folders in a frame on a Web page.
An update to the user agent string. The user agent string allows Web sites to detect the type of browser being used to access the site.
After installing Internet Explorer 3.0b/3.01b, the user agent string reported is one of the following, depending on the version of Internet Explorer:
```
    - 3.00 - NT - Mozilla/2.0 (compatible; MSIE 3.0; Update B;
      Windows NT)
    - 3.00 - Win95 - Mozilla/2.0 (compatible; MSIE 3.0; Update B; Windows
      95)
    - 3.01 - NT-Mozilla/2.0 (compatible; MSIE 3.01; Update B; Windows NT)
    - 3.01- Win95 - Mozilla/2.0 (compatible; MSIE 3.01; Update B; Windows
      95)
```
If you are not running patch B, the user agent string returned for version 3.01 is "Mozilla/2.0 (compatible; MSIE 3.01; Windows 95)." Similarly, the user agent string for version 3.0 is "Mozilla/2.0 (compatible; MSIE 3.0; Windows 95)."

Changes Made by Internet Explorer 3.0b/3.01b

The following files in the Windows\System folder are updated:

   File name      Size      Date     Version
   ---------------------------------------------
   Shdocvw.dll    507,760   3/7/97   4.70.1215
   Mshtml.dll     899,696   3/7/97   4.70.1215
   Isign32.dll     44,032   3/7/97   4.70.1087
   Advpack.dll     69,904   3/3/97   4.71.0603.0
   W95inf16.dll      2304   3/3/97   4.71.0016.0
   W95inf32.dll      4608   3/3/97   4.71.0016.0

Additional query words: 3.00 ie30 ie301 patch b ie3b ie30b ie301b

Keywords          : kbenv msiew95 msient 
Version           : 3.0 3.01
Platform          : WINDOWS

Last Reviewed: April 10, 1998