DLL Injection: Executing and Testing DLL's

DLL (Dynamic Link Library) Injection is the process of loading a DLL into target process so that code in the DLL might be executed in the context of the target process.

Example Code Snippet

How to test DLL
RUNDLL32.EXE dll_name,EntryPoint [options]

AppInit_DLLs value is found at
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Windows
We have to set Appinit_DLLs key value of the type REG_SZ to DLL's Path. Executables that do not link with User32.dll do not load AppInit DLLs.

NOTE: Above registry change might cause inconvenience as you might see too many pop-ups

References
http://www.exploit-db.com/exploits/14740/
http://www.exploit-db.com/papers/14813/
http://www.exploit-db.com/wp-content/themes/exploit/docs/242.pdf
http://www.ericphelps.com/batch/rundll/
http://blog.opensecurityresearch.com/2013/01/windows-dll-injection-basics.html