Before looking at the specific ...MachineOnly... function, let’s understand what cryptext.dll is. The file is a genuine Microsoft-signed system DLL located in C:\Windows\System32 . Its full name is “Microsoft Windows Cryptographic Extensions” or “Crypto Shell Extensions”.
DWORD CryptExtAddCERMachineOnlyAndHwnd( HWND hWnd, LPCWSTR lpszFileName, DWORD dwStoreLocation, DWORD dwAddFlags );
Given that cryptextdll is an internal library, Microsoft recommends using documented APIs for production code: cryptextdll cryptextaddcermachineonlyandhwnd work
While legitimate software uses this to install necessary security credentials, it is also a point of interest for security analysts:
An NSIS (Nullsoft Scriptable Install System) forum post from 2012 provides a glimpse into how developers tried to call this function programmatically. The user explored calling the CryptExtAddCER function using the System plug-in: Before looking at the specific
Import-Certificate -FilePath "cert.cer" -CertStoreLocation "Cert:\LocalMachine\Root"
Automated Malware Analysis Report for root.cer - Joe Sandbox Share public link To observe these functions in
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To observe these functions in action:
The command rundll32.exe cryptext.dll,CryptExtAddCERMachineOnlyAndHwnd is a specialized Windows system call used to directly into the local machine's certificate store.