Windows Zero-day

Very recently patched Windows zero-day vulnerability (CVE-2019-0859) in win32k.sys let hackers take control of unpatched Windows systems.

Security researchers from Kaspersky team recent addressed this Zero-day vulnerability in win32k.sys while it made an attempt to exploit one of their customers Microsoft Windows operating system.

A Local Privilege Escalation vulnerability was then reported later to Microsoft and released a patch for Zero-day along with 74 other security vulnerabilities.

This is actually the fifth vulnerability that consecutive exploited Local Privilege Escalation vulnerability in Windows that uncovered by Kaspersky team researchers, here the previous zero-days in very recent past.

Zero-day Exploit Process in Windows win32k.sys

This Vulnerability is presented in the CreateWindowEx, a function that
creates an overlapped, pop-up, or child window with an extended style.

Attackers Exploiting this elevation of privilege vulnerability in Windows when Win32k component fails to properly handle objects in memory.

A PowerShell script mainly used by attackers for the post-exploitation process with a Base64 encoded command. 

The ultimate goal of this PowerShell script to download a second-stage script from https//pastebin.com.

This Second stage of the PowerShell executes the final stage which is also a PowerShell Script that you can see in below image.

Windows Zero-day
Third stage PowerShell script

According to Kaspersky, the third script is very simple and does the following:

  • Unpacks shellcode
  • Allocates executable memory
  • Copies shellcode to the allocated memory
  • Calls CreateThread to execute shellcode

At the final stage, the shellcode is to make a trivial HTTP reverse shell that leads to attackers gain complete control of the targeted victims Windows system.

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Also Read:

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