Threats / Microsoft / CVE-2021-36934
CVE-2021-36934
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft Windows vulnerability
Windows SAM file exposure through Volume Shadow Copy allows local privilege escalation to SYSTEM level when VSS shadow copies are accessible on the system drive.
Verdict
Today item — known-exploited.
A local attacker with user-level access can read the SAM database from available Volume Shadow Copies to extract credential material and escalate privileges to SYSTEM, compromising full system control.
CISA KEV Yes · 2022-02-105EPSS 0.67252 (verify live)6Exploit Public PoC7CVSS 7.83CISA SSVC Exploitation: active · Automatable: no · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Public proof-of-concept exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
6 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-02-10).
Probability (EPSS)
EPSS 0.67252 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 7.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:T/RC:C) · Affected: Microsoft, Windows. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
Weakness (CWE)
Mapped to CWE-1220 CWE-1220.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 203 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
Public exploit available
Public exploit tooling is catalogued for this CVE (a public proof-of-concept / detection template). Catalog entries: Metasploit module. We link the catalog page(s) only — no payload or code is hosted or restated here.Link, never host — the catalog page is the source; basicsecurity.net does not redistribute payloads.
WeaknessCWE-1220 · CWE-1220
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I identify that Volume Shadow Copies exist on the target system drive.
Business
System backup and recovery mechanisms create an unintended credential exposure vector.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I access and read the SAM file from an available VSS shadow copy without requiring administrative permissions.
Business
Authentication material stored in SAM becomes readable to any local user account.
3
Lateral reach — past segmentation narrative 3
Attacker
I extract password hashes or credentials from the SAM database and perform offline cracking or pass-the-hash attacks.
Business
User account credentials are compromised, enabling lateral movement and persistence.
4
Data at risk — exfiltration narrative 4
Attacker
I escalate my privileges from user level to SYSTEM level using the recovered credentials or authentication tokens.
Business
Attacker gains unrestricted control over the entire Windows system and all hosted services.
5
Lights out — disruption & extortion narrative 5
Attacker
I maintain persistent access and execute arbitrary code with maximum privileges.
Business
Complete system compromise enables data exfiltration, malware deployment, and lateral attacks on the network.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05