Remote code execution in Microsoft Windows Print Spooler

1) Code Injection

EUVDB-ID: #VU53886

Risk: Critical

CVSSv4.0: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Red]

CVE-ID: CVE-2021-34527

CWE-ID: CWE-94 - Improper Control of Generation of Code ('Code Injection')

Exploit availability: Yes

Description

The vulnerability allows a remote user to execute arbitrary code on the target system.

The vulnerability exists due to improper input validation within the RpcAddPrinterDriverEx() function. A remote user can send a specially crafted request to the Windows Print Spooler and execute arbitrary code with SYSTEM privileges.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Note, the vulnerability is being considered a zero-day and dubbed PrintNightmare. This is a different vulnerability than #VU54508 (CVE-2021-1675).

Mitigation

Install update from vendor's website.

Vulnerable software versions

Windows: 7 - 10 2004 10.0.19041.264

Windows Server: 2008 - 2019 2004

CPE2.3

• cpe:2.3:o:microsoft:windows:*:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:8.1:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:8.1_RT:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:10:Mobile:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:10:Gold:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:10:S:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:10_1507:10.0.10240.16405:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:10_1511:10.0.10586.3:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server:*:*:*:*:*:*:*:*

External links

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34527

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.