CVE-2021-27070: 
vulnerability analysis and mitigation

Windows 10 Update Assistant Elevation of Privilege Vulnerability (CVE-2021-27070) was disclosed on March 11, 2021. The vulnerability affects Microsoft Windows 10 versions 20H2 and 2004, as well as Windows Server 2016 versions 20H2 and 2004. This security flaw was initially reported to Microsoft on November 11, 2020, and was publicly disclosed on March 17, 2021 (ZDI Advisory).

The vulnerability exists within the Windows Update Assistant and stems from incorrect permissions on a directory. It has received a CVSS v3.1 base score of 7.8 (High) from NIST with the vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, while Microsoft assigned it a slightly lower score of 7.3 with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H. The vulnerability is classified under CWE-732 (Incorrect Permission Assignment for Critical Resource) (NVD).

If successfully exploited, this vulnerability allows attackers to escalate privileges and execute arbitrary code in the context of Administrator. The high severity ratings across confidentiality, integrity, and availability indicate that successful exploitation could result in complete system compromise (ZDI Advisory).

To exploit this vulnerability, an attacker must first obtain the ability to execute low-privileged code on the target system. The attack requires local access and user interaction for successful exploitation (ZDI Advisory).

Microsoft has released security updates to address this vulnerability. Users should apply the appropriate patches (KB5000802) for their affected systems to mitigate this security risk (NVD).