Home/CVE/Microsoft Windows SAM Local Privilege Escalation Vulnerability
CVE

CVE-2021-36934

Microsoft Windows SAM Local Privilege Escalation Vulnerability

<p>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.</p> <p>An attacker must have the ability to execute code on a victim system to exploit this vulnerability.</p> <p>After installing this security update, you <em>must</em> manually delete all shadow copies of system files, including the SAM database, to fully mitigate this vulnerabilty. <strong>Simply installing this security update will not fully mitigate this vulnerability.</strong> See <a href="https://support.microsoft.com/topic/1ceaa637-aaa3-4b58-a48b-baf72a2fa9e7">KB5005357- Delete Volume Shadow Copies</a>.</p>.

HIGH · CVSS 7.8 ⚠ CISA KEV EPSS 0.90423
Act now
  • Listed on CISA KEV (known exploited in the wild)
  • SSVC exploitation status: active
  • EPSS ≥ 0.50 - high probability of exploitation in the next 30 days
  • EPSS percentile: top 0% of all CVEs by exploitation likelihood
  • Public exploit or PoC is available
  • CVSS base score ≥ 7.0
Sigma rules10 YARA rules0
⬢

Required Remediation

Apply updates per vendor instructions.

◆

Threat Actors Linked

1
actorAPT29
▤

Affected Products & Versions

5
microsoft windows 10 1809< 10.0.17763.2114
microsoft windows 10 1909< 10.0.18363.1734
microsoft windows 10 2004< 10.0.19041.1165
microsoft windows 10 20h2< 10.0.19042.1165
microsoft windows 10 21h1< 10.0.19043.1165
⚠

Public Exploits & PoCs

1
pocpacketstormsecurity.com · HiveNightmare-AKA-SeriousSAM.htmlpacketstormsecurity.com
◈

Sigma Hunt Rules

10
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
relatedcriticalAntivirus Password Dumper Detection
relatedcriticalHacktool Execution - Imphash
relatedcriticalHackTool - Rubeus Execution
relatedcriticalPotential Credential Dumping Via LSASS Process Clone
relatedcriticalWCE wceaux.dll Access
relatedcriticalHackTool - QuarksPwDump Dump File
▣

Scoring & Timeline

7.8
HIGH · CVSS v3.1 · secure@microsoft.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD22 Jul 2021 · 07:15 AM
CVSS VectorCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
active
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

4
cisaKEV-CVE-2021-36934
msrcCVE-2021-36934Elevation of Privilege
splunk-security-content9251299c-ea5b-11eb-a8de-acde48001122
splunk-security-content57551656-ebdb-11eb-afdf-acde48001122
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36934PatchVendor Advisory
https://www.kb.cert.org/vuls/id/506989Third Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36934US Government Resource
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