![]() Luckily Windows 7 comes with a new feature that prevent the user from running a particular executable called AppLocker which can be used to block all but authorised internet browsers. Another reason IT Administrators might want to block running third-party browsers is the lack of group policy support which makes it very difficult for administrators configured the browser to corporate standards (e.g. ![]() Also having multiple browsers on network could mean that you have totally patched one browser using your patch management system only to have user use a different type of browser that is completely un-patches. This is even more exacerbated by the very large number of security updates associate with running multiple browsers. Is was released on November 9th, 2011.One of the problem that face IT Administrators today is keeping up with all the security updates you need to deploy to your computers to keep them secure. Update: hotfix KB2532445 fixes this issue (MS internal fix was KB370118). A new registry key (disabling the use completely) or linking them to a specific AppLocker rule (only allowing the use when a certain AppLocker rule is matched) would do nicely. I have submitted the code to Microsoft, asking them to fix this by adding a control mechanism for using the LOAD_IGNORE_CODE_AUTHZ_LEVEL and SANDBOX_INERT flags. Place the cursor inside the Sub RunExe().Paste the content of runexe.txt into the new module.Right mouse button on “Normal” -> Insert -> Module.Select the text you just typed, in this example select “C:\test.exe” without the newline.In an MS Word document, type in the path to an executable that is not allowed by SRP/AppLocker.This was my first ever Visual Basic script which shows how easy it is to write this bypass with all the needed information already out in the open. The macro is just a translation to VB of the C code written by Didier Stevens, so all the credit goes to him. I have written a proof of concept macro that allows you to select the full path to an executable which will be executed bypassing all AppLocker restrictions. This means that from within Microsoft Office applications like Word and Excel, the AppLocker restrictions are easily bypassed. While allowing Perl or Python on a locked down Windows system is probably not a good idea, Visual Basic for Applications is something most power users can’t do without. This includes whitelisted applications, shellcode injected into a running process by an exploit, or (whitelisted) scripting languages. Every single process with access to the Windows API can. The problem with this design is that not only windows installer files can set these flags. With these flags set, AppLocker will not block the DLLs and executables, ever. ![]() So Microsoft designed 2 special API flags for this case: LOAD_IGNORE_CODE_AUTHZ_LEVEL for LoadLibraryEx() to load DLLs and SANDBOX_INERT for CreateRestrictedToken() to load executables. Adding the %TEMP% directory to the AppLocker whitelist would be insecure. Installer (msi) files often contain executables and DLLs that are placed in a temporary location and then executed during the installation process. (I don’t quite get what the point of using a whitelist is when users are still allowed to install new programs.) This poses an potential deadlock. ![]() The default AppLocker rules allow users to run Windows installer files. Apparently one challenge Microsoft faced when designing AppLocker was the installation of new software. An anonymous comment pointed out an even bigger issue: starting new processes (=programs) that are not permitted by AppLocker.īefore you think these are l33t hacks that will be fixed soon, read those blog entries. While I was looking into the usefulness of Windows AppLocker Belgian security researcher Didier Steven posted a blog entry explaining that he found a way to load DLLs that are not permitted by AppLocker.
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