CVEs / CVE-2021-36934
CVE-2021-36934: Microsoft Windows SAM Local Privilege Escalation Vulnerability
- Known exploited in the CISA KEV catalog since 10 Feb 2022
- medium 4.6 CVSS 2.0 (NVD)
- EPSS 67.2% chance of exploitation in the next 30 days, higher than 99% of CVEs (30 Oct 2026)
- Last changed at its sources
Are you affected? Check your servers with Stackurity: it lists the software on each server and the vulnerabilities to fix first.
Check your servers with Stackurity Already using Stackurity? Search for CVE-2021-36934
Summary
If a Volume Shadow Copy (VSS) shadow copy of the system drive is available, users can read the SAM file which would allow any user to escalate privileges to SYSTEM level.
Description
An elevation of privilege vulnerability exists because of overly permissive Access Control Lists (ACLs) on multiple system files, including the Security Accounts Manager (SAM) database. An attacker who successfully exploited this vulnerability could run arbitrary code with SYSTEM privileges. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. An attacker must have the ability to execute code on a victim system to exploit this vulnerability. After installing this security update, you must manually delete all shadow copies of system files, including the SAM database, to fully mitigate this vulnerabilty. Simply installing this security update will not fully mitigate this vulnerability. See KB5005357- Delete Volume Shadow Copies.
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| Microsoft Windows 10 Version 1809 | from 10.0.17763.0, before 10.0.17763.2114 | 10.0.17763.2114 |
| Microsoft Windows 10 Version 1809 | from 10.0.0, before 10.0.17763.2114 | 10.0.17763.2114 |
| Microsoft Windows 10 Version 1909 | from 10.0.0, before 10.0.18363.1734 | 10.0.18363.1734 |
| Microsoft Windows 10 Version 2004 | from 10.0.0, before 10.0.19041.1165 | 10.0.19041.1165 |
| Microsoft Windows 10 Version 20H2 | from 10.0.0, before 10.0.19042.1165 | 10.0.19042.1165 |
| Microsoft Windows 10 Version 21H1 | from 10.0.0, before 10.0.19043.1165 | 10.0.19043.1165 |
Exploitation
| In CISA KEV since | 10 Feb 2022 |
|---|---|
| Due date for US federal agencies | 24 Feb 2022 |
| Used in ransomware campaigns | Unknown |
| Required action | Apply updates per vendor instructions. |
Severity
| CVSS 2.0 | 4.6 mediumAV:L/AC:L/Au:N/C:P/I:P/A:PScored by NVD |
|---|
References
- CVE-2021-36934 on NVD
- CVE-2021-36934 in the CISA KEV catalog
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36934 Patch, Vendor Advisory
- http://packetstormsecurity.com/files/164006/HiveNightmare-AKA-SeriousSAM.html Third Party Advisory, VDB Entry
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36934 Patch, Vendor Advisory
- https://www.kb.cert.org/vuls/id/506989 Third Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36934 US Government Resource
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.