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Summary

A report of a potential local privilege escalation vulnerability was submitted to ESET by the Zero Day Initiative (ZDI). It potentially allows an attacker to misuse the AMSI scanning feature in specific cases. ESET mitigated the issue and recommends using the most recently released product versions, as detailed below.

Details

On November 18, 2021, ESET became aware of a potential vulnerability of local privilege escalation in its products for Windows. According to the report, submitted by the Zero Day Initiative (ZDI), an attacker who is able to get SeImpersonatePrivilege can misuse the AMSI scanning feature to elevate to NT AUTHORITY\SYSTEM in some cases. The SeImpersonatePrivilege is by default available to the local Administrators group and the device's Local Service accounts, which are already highly privileged and thus limit the impact of this vulnerability.

ESET investigated and verified this report and prepared new builds of its products that are not susceptible to this vulnerability.

The CVE ID reserved by ESET for this vulnerability is CVE-2021-37852 with the following CVSS v3 vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

To the best of our knowledge, there are no existing exploits that take advantage of this vulnerability in the wild.

Solution

ESET prepared the following fixed product versions that are not susceptible to the vulnerability and recommends that users upgrade to them as soon as possible:

• ESET NOD32 Antivirus, ESET Internet Security, ESET Smart Security and ESET Smart Security 15.0.19.0 (released on December 8, 2021)
• ESET Endpoint Antivirus for Windows and ESET Endpoint Security for Windows 9.0.2032.6 and 9.0.2032.7 (released on December 16, 2021)
• ESET Endpoint Antivirus for Windows and ESET Endpoint Security for Windows 8.0.2028.3, 8.0.2028.4, 8.0.2039.3, 8.0.2039.4, 8.0.2044.3, 8.0.2044.4, 8.1.2031.3, 8.1.2031.4, 8.1.2037.9 and 8.1.2037.10 (released on January 25, 2022)
• ESET Endpoint Antivirus for Windows and ESET Endpoint Security for Windows 7.3.2055.0 and 7.3.2055.1 (released on January 31, 2022)
• ESET Server Security for Microsoft Windows Server 8.0.12010.0 (released on December 16, 2021)
• ESET File Security for Microsoft Windows Server 7.3.12008.0 (released on January 12, 2022)
• ESET Security for Microsoft SharePoint Server 8.0.15006.0 (released on December 16, 2021)
• ESET Security for Microsoft SharePoint Server 7.3.15002.0 (released on January 12, 2022)
• ESET Mail Security for IBM Domino 8.0.14006.0 (released on December 16, 2021)
• ESET Mail Security for IBM Domino 7.3.14003.0 (released on January 26, 2021)
• ESET Mail Security for Microsoft Exchange Server 8.0.10018.0 (released on December 16, 2021)
• ESET Mail Security for Microsoft Exchange Server 7.3.10014.0 (released on January 26, 2022)

Users of ESET Server Security for Microsoft Azure are advised to upgrade ESET File Security for Microsoft Azure to the latest version of ESET Server Security for Microsoft Windows Server.

Affected programs and versions

The following product versions are susceptible to the vulnerability when running on Windows 10 and later or Windows Server 2016 and later:

• ESET NOD32 Antivirus, ESET Internet Security, ESET Smart Security and ESET Smart Security Premium from version 10.0.337.1 to 15.0.18.0
• ESET Endpoint Antivirus for Windows and ESET Endpoint Security for Windows from version 6.6.2046.0 to 9.0.2032.4
• ESET Server Security for Microsoft Windows Server 8.0.12003.0 and 8.0.12003.1, ESET File Security for Microsoft Windows Server from version 7.0.12014.0 to 7.3.12006.0
• ESET Server Security for Microsoft Azure from version 7.0.12016.1002 to 7.2.12004.1000
• ESET Security for Microsoft SharePoint Server from version 7.0.15008.0 to 8.0.15004.0
• ESET Mail Security for IBM Domino from version 7.0.14008.0 to 8.0.14004.0
• ESET Mail Security for Microsoft Exchange Server from version 7.0.10019 to 8.0.10016.0