Threat Signal Report

Microsoft Patch Tuesday Fixed Zero Day Elevation of Privilege Vulnerability (CVE-2023-21674)

description-logo Description

Microsoft has released 98 security patches for this month's January 2023 Patch Tuesday release. One of the fixes is for CVE-2023-21674 (Windows Advanced Local Procedure Call (ALPC) Elevation of Privilege Vulnerability). The vulnerability is rated critical, and exploitation of the vulnerability was observed in the field by Microsoft. This has a CVSS score of 8.8.


Why is this Significant?

This is significant because Microsoft observed CVE-2023-21674 being exploited as a 0-day, as such the patch should be applied as soon as possible. As CVE-2023-21674 is a local privilege escalation vulnerability, attackers need to either chain the exploit for CVE-2023-21674 with other exploit(s) or have already gain access to the victim's network, which lower the severity.


What is CVE-2023-21674?

CVE-2023-21674 is a Local Privilege Escalation vulnerability in Windows Advanced Local Procedure Call (ALPC), which attackers can exploit for a browser sandbox escape to gain SYSTEM privileges in vulnerable systems.


Has the Vendor Released an Advisory?

Yes, Microsoft released an advisory. See the Appendix for a link to "Windows Advanced Local Procedure Call (ALPC) Elevation of Privilege Vulnerability".


Has the Vendor Released a Patch for CVE-2023-21674?

Yes, Microsoft released a patch for CVE-2023-21674 as part of January Patch Tuesday on January 10, 2023.


What is the Status of Protection?

FortiGuard Labs has released the following IPS signature for CVE-2023-21674 in version 22.472 on January 10th, 2023:

  • MS.Windows.ALPC.CVE-2023-21674.Privilege.Elevation (default action is set to "pass")

Telemetry

Appendix

Windows Advanced Local Procedure Call (ALPC) Elevation of Privilege Vulnerability (Microsoft)

CVE-2022-21674 (MITRE)

MS.Windows.ALPC.CVE-2023-21674.Privilege.Elevation (Fortinet)


Definitions

Traffic Light Protocol

Color When Should it Be used? How may it be shared?

TLP: RED

Not for disclosure, restricted to participants only.		 Sources may use TLP:RED when information cannot be effectively acted upon by additional parties, and could lead to impacts on a party's privacy, reputation, or operations if misused. Recipients may not share TLP:RED information with any parties outside of the specific exchange, meeting, or conversation in which it was originally disclosed. In the context of a meeting, for example, TLP:RED information is limited to those present at the meeting. In most circumstances, TLP:RED should be exchanged verbally or in person.

TLP: AMBER

Limited disclosure, restricted to participants’ organizations.		 Sources may use TLP:AMBER when information requires support to be effectively acted upon, yet carries risks to privacy, reputation, or operations if shared outside of the organizations involved. Recipients may only share TLP:AMBER information with members of their own organization, and with clients or customers who need to know the information to protect themselves or prevent further harm. Sources are at liberty to specify additional intended limits of the sharing: these must be adhered to.

TLP: GREEN

Limited disclosure, restricted to the community.		 Sources may use TLP:GREEN when information is useful for the awareness of all participating organizations as well as with peers within the broader community or sector. Recipients may share TLP:GREEN information with peers and partner organizations within their sector or community, but not via publicly accessible channels. Information in this category can be circulated widely within a particular community. TLP:GREEN information may not be released outside of the community.

TLP: WHITE

Disclosure is not limited.		 Sources may use TLP:WHITE when information carries minimal or no foreseeable risk of misuse, in accordance with applicable rules and procedures for public release. Subject to standard copyright rules, TLP:WHITE information may be distributed without restriction.