CVE-2019-0803 Windows flaw exploited to deliver PowerShell Backdoor
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2019-0803 +1 in the same advisory: …0859 | Local Privilege Escalation in Microsoft Win32k Kernel Component CVE-2019-0803 is a privilege escalation flaw in Microsoft's Win32k kernel component caused by improper handling of objects in memory. It is triggered locally when code already running on a Windows system reaches the vulnerable Win32k object-handling path, allowing memory corruption that the attacker can leverage. Successful exploitation lets the attacker run arbitrary code in kernel mode, elevating from a low-privileged account to full system-level control. Per the available data, the affected component is Microsoft Win32k across Windows installations, though specific affected Windows versions and builds are not enumerated in the source data and should be confirmed against Microsoft's advisory. Exploitation is confirmed in the wild: CISA added it to the KEV catalog on 2021-11-03 with known ransomware use, and EPSS assigns a 45.2% probability of exploitation within 30 days (99th percentile). Do: Apply Microsoft Windows security updates per vendor instructions — this flaw was fixed in Microsoft's April 2019 security updates, so ensure systems are running those or later cumulative updates and verify by checking OS build numbers. Prioritize patching endpoints and servers where untrusted or low-privileged users can execute code, given documented ransomware chaining. Treat KEV status as a deadline: systems unpatched for this Win32k flaw should be considered actively targeted. | 7.8 | 45% | KEV ransomware |
| masshundreds of millions of Windows desktops and servers (Win32k is a core component shipped with essentially all Windows installations) |
Full article370 words · extracted from securityaffairs.com · click to collapse
A recently fixed local privilege escalation flaw in windows (CVE-2019-0803) had been exploited by bad actors to deliver PowerShell Backdoor.
April 2019 Patch Tuesday security updates addressed a local privilege escalation flaw in Windows operating system, tracked as CVE-2019-0859 that had been exploited by threat actors to deliver a PowerShell backdoor.
The flaw could allow an attacker to escalate privileges on the target system, it exists due to the way the Win32k component handles objects in memory. The flaw could allow an authenticated attacker to execute arbitrary code in kernel mode.
The CVE-2019-0859 was the fifth Windows zero-day discovered by Kaspersky experts in a few months. The previously reported flaws had been exploited in targeted campaigns carries out by several threat actors, including FruityArmor and SandCat.
The vulnerability was discovered by Kaspersky Lab that reported it to the tech giant on March 17.
“In early March, our proactive security technologies uncovered an attempt to exploit a vulnerability in Microsoft Windows. The analysis revealed a zero-day vulnerability in our old friend win32k.sys, in which similar vulnerabilities have been discovered four times already.” “We reported the problem to the developer, and the vulnerability was fixed with a patch, released on April 10.” reads the post published by Kaspersky.
According to the analysis published by Kaspersky, the CVE-2019-0859 is a Use-After-Free issue that ties with the CreateWindowEx function.
The security firm revealed that the vulnerability has been used by an unnamed threat actor to execute PowerShell, Microsoft’s task automation and configuration management framework.
After the successful exploitation of the CVE-2019-0859, the exploit executed PowerShell with a Base64 encoded command to download a second-stage script from https//pastebin.com. This second stage PowerShell executes the final third stage, which is also a PowerShell script that unpacks shellcode and executes it.
Attackers used the shellcode to create an HTTP reverse shell that allows them to take complete control of the targeted device.
“The exploit we found in the wild was targeting 64-bit versions of Windows (from Windows 7 to older builds of Windows 10) and exploited the vulnerability using the well-known HMValidateHandle technique to bypass ASLR,” continue the researchers.
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(SecurityAffairs – CVE-2019-0803, Zero-day
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Text extracted automatically; images, tables and formatting may be missing. Original: https://securityaffairs.com/83903/hacking/cve-2019-0803-windows-flaw.html