AppLocker Commander
Properly Hardening Your System: The 2 Core Rules for Maximum Security
Now that we have covered the basics and technologies, it is time for practice: What does an optimal hardening strategy look like? Basically, every effective application control builds on two simple rule types: Allow and Deny. Three criteria are available for implementation: paths, publisher certificates, and hash values.
Rule 1: Allow – The Path Strategy as the Gold Standard
The safest and most maintenance-friendly strategy is to allow programs to run exclusively from protected system folders (such as C:\Program Files or C:\Windows).
- Basic rule: Folders where regular users possess write permissions must never execute programs or scripts.
- Precision over convenience: If a program must run from a protected folder, do not whitelist the entire root directory—only the exact subdirectory required.
Exceptions & Compromises
What to do when an application must run from a folder with write permissions?
- 1. Publisher Certificates (Certificate Rules): Trust is placed in the trusted publisher of the software. Warning: This already weakens protection, as theoretical circumvention is possible here.
- 2. Hash Values (Digital Fingerprints): This can be remedied with a hash value: The program is only allowed to run if it is precisely that single file. This offers maximum security for this edge case, but makes the software harder to maintain (e.g., during updates).
Recommendation: Ideally, default to allowing only protected paths. Certificates and hash values should serve solely as targeted exceptions.
Rule 2: Deny – Locking Out Powerful Windows Tools
Attackers preferentially exploit built-in Windows tools ("Living off the Land") in everyday operations. Therefore, system hardening must include targeted blocking of these utilities.
- Standard: Deny all powerful Windows tools and script interpreters (such as
PowerShell,cmd.exe,cscript.exe,wscript.exe). These are not needed in normal day-to-day operations. - Practical Exception: If certain programs or scripts require these tools in network environments, allow only the strictly necessary ones and consistently disable the rest.
Pro Tip: Initially Blocking Script Interpreters for Administrators
To minimize security risks during ongoing operations—without having to rebuild existing processes immediately—dangerous script interpreters should first be specifically blocked for administrators.
- The Benefit: Everyday scripts of regular users continue to function smoothly. At the same time, it effectively prevents (potentially compromised) administrator accounts from executing scripts with high privileges on legacy systems, thereby causing massive damage.
- Long-term Goal (.exe instead of script): To completely eliminate the risk later, required scripts should gradually be replaced by
.exefiles. Thanks to modern AI tools, a script can be converted into a small executable in just a few seconds—completely without programming skills. This.execan then be cleanly whitelisted via AppLocker, so that script interpreters can ultimately be disabled network-wide.
Conclusion
Anyone who consistently implements the combination of Allow (protected paths) and Deny (Windows tools/script interpreters) elevates their operating system to the level of a high-security environment—exactly as required in mission-critical infrastructures.
Part 7: Third-Party Market & Summary
An overview of alternatives and the grand conclusion of our series.