Mimikatz is a powerful credential-harvesting tool that started life as a legitimate security research project but has become one of the most widely abused utilities in modern cyberattacks. Originally developed by French security researcher Benjamin Delpy to demonstrate Windows authentication vulnerabilities, this open-source application can extract plaintext passwords, password hashes, PIN codes, and Kerberos tickets from a running Windows system's memory. While penetration testers use it legally to audit network security, threat actors deploy it routinely in ransomware campaigns, corporate espionage, and lateral movement attacks across networks.
If your Windows computer has been compromised with Mimikatz, the attacker likely already has administrative access and may be using your stored credentials to access other systems on your network. The presence of this tool is a serious indicator that your machine has been deeply compromised, and immediate action is required to prevent further damage.
Threat Profile
| Canonical Name | Mimikatz |
| Threat Type | Credential Dumping Tool / Post-Exploitation Utility |
| Platform | Windows (all versions from XP through Windows 11) |
| File Type | Windows PE Executable (.exe), PowerShell scripts, reflective DLL injection |
| First Observed | 2011 (public release) |
| Last Updated | Actively maintained as of September 2026 |
| Detection Rate | High (90%+ by major AV engines when unobfuscated) |
| Common Aliases | MimiKatz, mimikatz.exe, mimilib.dll, kiwi (Metasploit module) |
| Prevalence | Extremely high — found in majority of advanced persistent threat campaigns |
| Severity | Critical (enables complete credential compromise) |
| Legitimate Use | Yes — widely used by security professionals for authorized penetration testing |
| Typical Payload Size | 1-2 MB (standalone executable), varies with obfuscation/packing |
How It Spreads
Mimikatz itself doesn't spread like traditional malware. It's a post-exploitation tool, meaning attackers deploy it after they've already gained access to your system through other means. Think of it as the crowbar a burglar uses once they're inside your house — not the method they used to break in. The initial compromise typically comes from phishing emails, software vulnerabilities, weak passwords, or other malware that establishes a foothold on your machine.
Once an attacker has administrative access, they download or inject Mimikatz into memory to harvest credentials. Because Mimikatz is open-source and freely available on GitHub, attackers don't need specialized skills to obtain it. They often disguise it by renaming the executable, compiling modified versions, or using PowerShell-based implementations that run entirely in memory without touching the disk.
Common deployment methods include:
- Phishing attachments — Macro-laden Office documents or executable files that drop Mimikatz after initial infection
- Exploited vulnerabilities — Attackers use software flaws (like EternalBlue) to gain system access, then deploy Mimikatz
- Compromised RDP sessions — Weak Remote Desktop passwords allow attackers to log in and manually run the tool
- Trojanized software — Fake installers or cracked applications that bundle Mimikatz with legitimate programs
- Lateral movement — After stealing credentials from one machine, attackers use those credentials to deploy Mimikatz across an entire network
- PowerShell Empire / Metasploit — Automated attack frameworks that include Mimikatz modules for credential harvesting
What It Does On Your Machine
Mimikatz targets the Local Security Authority Subsystem Service (LSASS), a Windows process that handles authentication and stores credentials in memory. When you log into Windows, type a password, or connect to network resources, those credentials temporarily exist in LSASS memory to facilitate authentication. Mimikatz exploits this by reading directly from that protected memory space, extracting plaintext passwords, NTLM hashes, Kerberos tickets, and other authentication tokens.
On older Windows versions (before Windows 8.1/Server 2012 R2), LSASS stored plaintext passwords in memory by default, making credential theft trivial. Microsoft implemented protections like Credential Guard in newer versions, but Mimikatz continues to evolve with new techniques. Even with protections enabled, it can often extract password hashes that attackers can use for "pass-the-hash" attacks to authenticate without knowing the actual password.
The tool includes numerous modules beyond basic credential dumping. It can generate Kerberos "Golden Tickets" that grant permanent domain administrator access, elevate privileges on a local machine, extract credentials from Registry hives and memory dumps, and even manipulate smart card authentication. In a typical ransomware scenario, attackers use Mimikatz to harvest domain administrator credentials, then use those credentials to deploy encryption payloads across hundreds of machines simultaneously.
You won't see obvious symptoms like pop-ups or system slowdowns with Mimikatz. It runs silently, completes its work in seconds, and terminates. The real damage becomes apparent later — unauthorized logins to your accounts, lateral movement to other computers on your network, or a full-blown ransomware attack using your stolen credentials. Most users only discover Mimikatz was used after forensic investigation of a larger breach.
Manual Removal — Step by Step
Disconnect from all networks immediately
Unplug your Ethernet cable and disable Wi-Fi. If you're on a corporate network, notify your IT department before proceeding. Mimikatz is often part of an active attack — isolation prevents further credential harvesting and lateral movement to other systems.
Boot into Safe Mode with Networking
Restart your computer and repeatedly press F8 (or Shift+F8 on newer systems) during boot. Select "Safe Mode with Networking" from the menu. This loads Windows with minimal drivers and prevents most malware from auto-starting, while still allowing you to download tools if needed.
Check running processes for suspicious executables
Open Task Manager (Ctrl+Shift+Esc) and examine the Processes tab. Look for unfamiliar .exe files in unusual locations like C:\Users\Public\, C:\Windows\Temp\, or C:\ProgramData\. Right-click suspicious entries and select "Open file location." Mimikatz may be renamed to mimic legitimate Windows processes (svchost.exe, lsass.exe, etc.) but located in wrong directories.
Scan for malicious files and registry changes
Run a full system scan with an updated anti-malware tool (Malwarebytes, Microsoft Defender Offline, or similar). Pay special attention to detection of "HackTool:Win32/Mimikatz" or similar classifications. Check HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\WDigest in Registry Editor — if "UseLogonCredential" is set to 1, change it to 0 or delete the value entirely to disable plaintext credential caching.
Delete identified malicious files
Based on scan results and manual investigation, delete all Mimikatz-related files. Common locations include user temp directories, Downloads folders, and system directories attackers have write access to. Be certain of file identity before deletion — if you're unsure whether a file is legitimate, document its location and hash before removing it.
Search for evidence of initial compromise
Review Windows Event Viewer (Security logs, particularly Event IDs 4624, 4625, 4672 for logins). Check browser download history and email attachments from the past 30 days. Identify how the attacker gained access originally — this might be a phishing email, exploited vulnerability, or weak password. Address this entry point or reinfection is likely.
Change ALL passwords from a clean device
This is critical: assume every password you've used on the compromised machine has been stolen. From a different, known-clean computer or smartphone, change passwords for email accounts, banking, work systems, cloud storage — everything. Enable two-factor authentication wherever possible. For corporate networks, your IT team must reset domain credentials and revoke existing Kerberos tickets.
Apply Windows security updates
Run Windows Update and install all available patches, especially security updates. Enable Credential Guard on Windows 10/11 Enterprise editions if available (requires UEFI, Secure Boot, and virtualization support). Configure Windows Defender Credential Guard through Group Policy or Device Guard Readiness Tool to prevent future memory-based credential theft.
Monitor for signs of persistent access
For the next 2-4 weeks, watch for unauthorized account logins, unexpected network traffic, or new scheduled tasks. Check Startup programs (msconfig or Task Manager > Startup tab) and Windows Services for unfamiliar entries. Advanced attackers often establish multiple persistence mechanisms beyond Mimikatz itself.
Consider professional forensic analysis
If this is a business machine, if you handle sensitive data, or if you've observed other indicators of advanced attack (ransomware notes, data exfiltration, multiple compromised machines), professional incident response is warranted. Mimikatz is rarely used in isolation — it's typically part of a sophisticated, multi-stage attack that requires expert remediation.
Prevention
- Enable Credential Guard and Remote Credential Guard on supported Windows 10/11 systems to isolate LSASS using virtualization-based security, making memory-scraping attacks significantly harder.
- Restrict administrative privileges to the absolute minimum number of users. Run daily operations with standard user accounts — Mimikatz requires administrative access to read LSASS memory, so privilege limitation is your primary defense.
- Implement network segmentation and least-privilege access so that even if credentials are stolen, attackers can't move laterally across your entire network with domain admin accounts.
- Deploy endpoint detection and response (EDR) tools that monitor for suspicious LSASS access patterns, memory injection, and credential dumping behaviors rather than relying solely on signature-based antivirus.
- Disable WDigest authentication on all Windows systems by setting HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\WDigest\UseLogonCredential to 0, preventing storage of plaintext credentials in memory.
- Use Windows Defender Application Control or AppLocker to whitelist approved executables and prevent unauthorized tools from running, even if an attacker gains access to your system.
- Keep all systems patched and current — attackers often use known vulnerabilities to gain the initial foothold that allows Mimikatz deployment. Automated patch management eliminates this entry point.
- Train users to recognize phishing attempts since social engineering remains the most common way attackers gain the initial access needed to deploy post-exploitation tools like Mimikatz.
Bring It In
Mimikatz infections indicate serious security breaches that extend beyond simple malware removal. If you've discovered this tool on your system, you're likely dealing with credential theft, potential data exfiltration, and possibly an ongoing attack targeting your network. Our technicians at Computer Repair Roswell have forensic-level experience investigating these sophisticated compromises — we'll identify not just the Mimikatz presence, but how the attacker gained access, what credentials were exposed, and what other persistence mechanisms they may have established.
We're located at 1735 Hembree Road, Suite 200, Roswell, GA 30076, and available at (770) 679-9432. For situations like this, we recommend bringing your machine in immediately for emergency service. We'll perform complete forensic analysis, credential remediation consultation, and security hardening to prevent reinfection. Whether you're an individual user or managing a small business network, Mimikatz represents a critical threat that demands expert attention — call us today to ensure the breach is fully contained and your credentials are secured.