Microsoft releases emergency Internet Explorer security update

Microsoft launched an out-of-band emergency security update for Internet Explorer on September 23, 2019 for all supported variations of Windows.

The emergency update is simply out there on the Microsoft Update Catalog web site on the time of writing and never by means of Windows Update or WSUS.

Some assist articles present little info. The Windows 10 update description merely states “
Updates to enhance security when utilizing Internet Explorer” with out going into additional element. The web page hyperlinks to the Security Update Guide which, after some digging, results in the CVE of the vulnerability.

internet explorer security out of band

The assist web page for the cumulative update for Internet Explorer gives extra info and a direct hyperlink to the CVE.

It states:

This security update resolves a vulnerability in Internet Explorer. A distant code execution vulnerability exists in the best way that the scripting engine handles objects in reminiscence in Internet Explorer. The vulnerability might corrupt reminiscence in such a manner that an attacker might run arbitrary code within the context of the present consumer. The security update addresses the vulnerability by altering how the scripting engine handles objects in reminiscence.

The similar info is supplied on the CVE web page as effectively. Microsoft notes that an attacker might take management of the attacked system if the assault succeeds which might enable the attacker to put in or take away applications, view, change or delete recordsdata, or create new consumer accounts.

The security difficulty is exploited actively in line with Microsoft; an attacker might create a particularly ready web site to take advantage of the problem in Internet Explorer.

Microsoft revealed a workaround to guard techniques if the launched updates can’t be put in at this level. The workaround might cut back performance “for elements or options that depend on jscript.dll”.

The instructions must be run from an elevated command immediate.

Workaround for 32-bit techniques:

  • takeown /f %windirpercentsystem32jscript.dll
  • cacls %windirpercentsystem32jscript.dll /E /P everybody:N

Workaround for 64-bit techniques:

  • takeown /f %windirpercentsyswow64jscript.dll
  • cacls %windirpercentsyswow64jscript.dll /E /P everybody:N
  • takeown /f %windirpercentsystem32jscript.dll
  • cacls %windirpercentsystem32jscript.dll /E /P everybody:N

The workaround may be undone by working the next instructions from an elevated command immediate:

Undo 32-bit:

  • cacls %windirpercentsystem32jscript.dll /E /R everybody

Undo 64-bit

  • cacls %windirpercentsystem32jscript.dll /E /R everybody
  • cacls %windirpercentsyswow64jscript.dll /E /R everybody

List of updates that repair the vulnerability:

What about Windows Updates?

Microsoft has not launched the update by way of Windows Update or WSUS. Susan Bradley notes that the corporate might launch the update on September 24, 2019 by way of Windows Update and WSUS however that has not been confirmed by Microsoft.

It is a bit puzzling that Microsoft releases an out-of-band security update that addresses a difficulty that’s exploited within the wild however chooses to launch it as an update that must be downloaded and put in manually solely.

Closing Words

Should or shouldn’t you put in the update instantly? It is a security update however it’s only out there by way of the Microsoft Update Catalog web site on the time of writing.

I nonetheless would suggest putting in it however it is best to create a system backup, e.g. utilizing Macrium Reflect or Paragon Backup & Recover Free, earlier than you accomplish that as one by no means is aware of lately updates introduce undesirable uncomfortable side effects or problems with their very own.

Now You: set up or wait, what’s your place?

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