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  • Yet another JScript vulnerability

    Home Forums AskWoody blog Yet another JScript vulnerability

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      • #2086420
        woody
        Manager

        Internet Explorer, the gift that keeps on giving. Looks like we have a brand new JScript bug. According to ADV200001: A remote code execution vulnerab
        [See the full post at: Yet another JScript vulnerability]

        5 users thanked author for this post.
      • #2086433
        abbodi86
        AskWoody_MVP

        Yes, let’s hope they don’t repeat September debacle šŸ™‚

        2 users thanked author for this post.
      • #2086474
        fernlady
        AskWoody Lounger

        I’m a home user with one windows7 computer and have Firefox 72.0.1 as my default browser, should I disable JScript in IE11?

        Under Scripting there are 3 areas that are enabled, Active scripting, Enable XSS filter & Scripting of Java applets. Allow Programmatic clipboard access which is set to Prompt. Disable all???

        Windows 7 Home Premium x64 AMD Group A Realtek PCLe GBE Family Controller

        • This reply was modified 1 year, 8 months ago by fernlady.
        • #2086540
          anonymous
          Guest

          I would open Control Panel and go to Programs and Features. Then on the top left click on “Turn Windows Features on or off”.

          Next find Internet Explorer 11 and uncheck the box.

          I did this a couple of years ago and it hasn’t affected other programs or websites for me.

          Consider using NoScript with Firefox and although there is a bit of a learning curveĀ  any inconvenience will give you a more secure system as payback. Also HTTPS Everywhere is another secure option.

          1 user thanked author for this post.
          • #2086602
            fernlady
            AskWoody Lounger

            That was easy. Thank you, so far no problems.

            Windows 7 Home Premium x64 AMD Group A Realtek PCLe GBE Family Controller

            • #2110097
              Moonbear
              AskWoody Lounger

              If you do ever need to re-enable Internet Explorer, It may not recreate the desktop icon when you do.

              Just something to watch out for.

               

      • #2086555
        Microfix
        AskWoody MVP

        Looks like MSFT has issued a temporary workaround for the IE vulnerability with instructions how to implement and undo for when a hot-fix-patch is released.

        https://portal.msrc.microsoft.com/en-us/security-guidance/advisory/ADV200001

        MSFT catalog patch for Windows 7 only? dunno, time will tell..

        | Quality over Quantity |
        1 user thanked author for this post.
        • #2086562
          woody
          Manager

          Yep, that’s the “Turn off JScript” fix I mentioned.

          Nice of them to announce this on a Friday evening before a three-day (US) weekend…

          1 user thanked author for this post.
        • #2086829
          anonymous
          Guest

          As usual MS forgot to mention in the FAQ,Ā  this temporary workaround also break Windows Media Player on Win 10. You’ll get a “Server execution failedĀ error” when trying to play an MP4.

          3 users thanked author for this post.
        • #2086857
          EstherD
          AskWoody Lounger

          It also causes “sfc” on Win7 to emit a cryptic error message, something about files it tried to restore but couldn’t, presumably because “sfc” also can no longer read the jscript.dll files after the workaround is implemented. Since the logfile generated by “sfc” is effectively unparsable by mere mortals, it is difficult to determine exactly what “sfc” is complaining about. Therefore, you may not want to implement this workaround if you rely on “sfc” to validate the health of your Win7 system.

          3 users thanked author for this post.
      • #2086604
        Moonbear
        AskWoody Lounger

        If your not directly using Internet Explorer to access the internet, should this be worried about?

        I have IE’s outbound connection blocked with Windows Firewall, should I also block the inbound connection as well?

        • #2086914
          woody
          Manager

          Not using IE is kind of a baseline security precaution.

          I don’t know if you’re vulnerable outside of IE, but I would guess that if the exposure were really all that significant, we would have a patch by now.

          4 users thanked author for this post.
          • #2087274
            Moonbear
            AskWoody Lounger

            In that case I’m leaving it alone, especially considering the issues being reported from using the workaround

      • #2086921
        AmbularD
        AskWoody Plus

        Interesting.Ā  I disabled jscript per the advisory, and Internet Explorer still worked fine (not that I use it much anymore,) but Firefox crashed at startup until I enabled it again.Ā  Waterfox, Pale Moon, and IceDragon, however, did not seem to be affected.

        Disabling jscript may also have broken Panda Dome, though I’m not sure about that, as this as a possible cause of the issues it was having did not occur to me until after I’d already given up in frustration and replaced it with Avast.

        i7-10700k - ASROCK Z590 Pro4 - 1TB 970 EVO Plus M.2 - DDR4 3200 x 32GB - GeForce RTX 3060 Ti FTW - Windows 10 Pro

        4 users thanked author for this post.
      • #2087082
        Mitja Kolsek
        AskWoody Plus

        We @0patch are planning to issue a micropatch for this next week which will prevent Internet Explorer from loading jscript.dll. This will not affect the permissions on jscript.dll and will likely keep the sfc command unaffected. It would be nice to learn from other users implementing Microsoft’s workaround what else that workaround breaks.

        5 users thanked author for this post.
      • #2087468
        Grargfar
        AskWoody Plus

        The workaround breaks printing to “Microsoft Print to PDF”. I had to revert it.

        1 user thanked author for this post.
      • #2110388
        MrToad28
        AskWoody Lounger

        I use Win7 PC’s and never use IE..Use Firefox, Firefox variant Pale moon & Chrome. Would I be affected by this Jscript issue?

        • #2110524
          Paul T
          AskWoody MVP

          Probably not, but it’s worth checking the browser web sites to see what they say about it.

          cheers, Paul

      • #2111606
        PKCano
        Manager

        @Mitja-Kolsek

        There are some other consequenses of the JavaScript bug posted here.

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