Unauthenticated NTLM coercion via LSARPC EFSRPC call
Published Aug 12, 2021 · Updated Aug 10, 2026
LSA spoofing in Microsoft Windows Server allows remote attackers to coerce a domain controller into NTLM authentication via LSARPC. The unauthenticated EfsRpcOpenFileRaw method accepts an attacker-controlled UNC path and makes the target authenticate to that host with its machine account. Network access to LSARPC is sufficient; relaying the credential to a susceptible AD CS endpoint allows certificate issuance and full Active Directory compromise.
Summary
What happened
LSA spoofing in Microsoft Windows Server allows remote attackers to coerce a domain controller into NTLM authentication via LSARPC. The unauthenticated EfsRpcOpenFileRaw method accepts an attacker-controlled UNC path and makes the target authenticate to that host with its machine account. Network access to LSARPC is sufficient; relaying the credential to a susceptible AD CS endpoint allows certificate issuance and full Active Directory compromise.
The record
- CVE
- CVE-2021-36942
- Published
- Aug 12, 2021
- Updated
- Aug 10, 2026
- Vendor
- Microsoft
- Product
- Windows Server 2019
- Classifications
- CWE-200, T1187
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 12, 2021CVE publishedPublication date reported by the CVE source.
- Nov 3, 2021Exploitation reportedCISA Known Exploited Vulnerabilities catalog entry
- Aug 10, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=10.0.17763.0 <10.0.17763.2114
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- PetitPotamfunctional · demonstrated
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Reported exploitation
- CISA Known Exploited Vulnerabilities catalog entryknown exploited catalog
Technologies
Your stack
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Your stack
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