Microsoft has warned millions of their windows users and issued an advisory about the unpatched zero-day vulnerability in Internet Explorer (IE) that is not being yet patched and currently being exploited under wild.
Microsoft said they were working on a fix and would release later on. Microsoft also said they were aware that the zero-day of Internet Explorer was being exploited in wild and described these attacks as limited target attacks i.e. they ere not being exploited broadly these attacks were being limited to the small number of users.
The vulnerability was listed as CVE-2020-0674 and rated moderate risk. Microsoft technically described this vulnerability as a remote code execution that exists in the scripting engine handles objects in memory in Internet Explorer which triggers through JScript.dll library.
The vulnerability could corrupt memory in such a way that an attacker could execute arbitrary code in the context of the current user. An attacker who successfully exploited the vulnerability could gain the same user rights as the current user,
The advisory
If the current user is logged on with administrative user rights, an attacker who successfully exploited the vulnerability could take control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights
Microsoft
Although Internet Explorer is yet not the default browser but still installed windows OS. Microsoft also said that all supported versions of Windows i.e. Windows 7, Windows 10, Windows 8.1 and Internet Explorer 9, Internet Explorer 10, and Internet Explorer 11 were impacted to this zero-day.
How to defend this attack
According to an advisory, preventing the loading of the JScript.dll library can manually block the exploitation of this vulnerability. To restrict access to JScript.dll run following commands in Windows
For 32-bit systems:
takeown / f% windir% \ system32 \ jscript.dll
cacls% windir% \ system32 \ jscript.dll / E / P everyone: N
For 64-bit systems:
takeown / f% windir% \ syswow64 \ jscript.dll
cacls% windir% \ syswow64 \ jscript.dll / E / P everyone: N
takeown / f% windir% \ system32 \ jscript.dll
cacls% windir% \ system32 \ jscript.dll / E / P everyone: N
After the patch is available reverse/ undo this by typing the following command.
For 32-bit systems:
cacls %windir%\system32\jscript.dll /E /R everyone
For 64-bit systems:
cacls %windir%\system32\jscript.dll /E /R everyone
cacls %windir%\syswow64\jscript.dll /E /R everyone
