Microsoft’s Internet Explorer zero-day workaround is breaking printing

Graham Cluley
Graham Cluley
@[email protected]

Microsoft's Internet Explorer zero-day workaround is breaking printers

As I reported earlier this month, there’s an unpatched zero-day vulnerability in Internet Explorer that is being exploited in targeted attacks.

Microsoft still hasn’t issued an official patch for what is technically known as CVE-2020-0674, but did detail what it described as a “workaround” in its security advisory, suggesting that concerned users might want to consider restricting access to JScript.dll.

But wait, there’s a problem.

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Users are now reporting on Reddit that after they applied the workaround they began to see errors when printing.

Reddit message

Microsoft says it is only aware of “limited targeted attacks” related to the Internet Explorer zero-day vulnerability. You’ll be the best judge as to whether your organisation needs to take that threat seriously, or whether it would prefer to have working printers.

If you need to undo the workaround, here are Microsoft’s instructions from the original security advisory:

How to undo the workaround

For 32-bit systems, enter the following command at an administrative command prompt:

cacls %windir%system32jscript.dll /E /R everyone

For 64-bit systems, enter the following command at an administrative command prompt:

cacls %windir%system32jscript.dll /E /R everyone
cacls %windir%syswow64jscript.dll /E /R everyone

Stay safe folks.

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Graham Cluley is a veteran of the cybersecurity industry, having worked for a number of security companies since the early 1990s when he wrote the first ever version of Dr Solomon's Anti-Virus Toolkit for Windows. Now an independent analyst, he regularly makes media appearances and is an international public speaker on the topic of cybersecurity, hackers, and online privacy. Follow him on Twitter, Mastodon, Bluesky, or drop him an email.

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