Get running processes using JNA

Question

I am trying to obtain a list of all currently running processes on a windows machine.

I am trying it with winapi calls via JNA to EnumProcesses -> OpenProcess -> GetModuleBaseNameW -> CloseHandle It fails at the OpenProcess call. GetLastError returns 5 (ERROR_ACCESS_DENIED).

This is my code:

public static final int PROCESS_QUERY_INFORMATION = 0x0400;
public static final int PROCESS_VM_READ = 0x0010;
public static final int PROCESS_VM_WRITE = 0x0020;
public static final int PROCESS_VM_OPERATION = 0x0008;


public interface Psapi extends StdCallLibrary {
    Psapi INSTANCE = (Psapi) Native.loadLibrary("Psapi", Psapi.class);

    boolean EnumProcesses(int[] ProcessIDsOut, int size, int[] BytesReturned);

    DWORD GetModuleBaseNameW(Pointer hProcess, Pointer hModule, byte[] lpBaseName, int nSize);

}

public interface Kernel32 extends StdCallLibrary {
    Kernel32 INSTANCE = (Kernel32) Native.loadLibrary("Kernel32", Kernel32.class);

    Pointer OpenProcess(int dwDesiredAccess, boolean bInheritHandle, int dwProcessId);

    boolean CloseHandle(Pointer hObject);

}

public static void main(String[] args) {
    int[] processlist = new int[1024];
    int[] dummylist = new int[1024];
    Psapi.INSTANCE.EnumProcesses(processlist, 1024, dummylist);

    for (int pid : processlist) {
        System.out.println(pid);
        Pointer ph = Kernel32.INSTANCE.OpenProcess(PROCESS_VM_READ, false, pid);

        try {
            Thread.sleep(1000);
        } catch (Exception ignore) {
        }

        System.err.println(com.sun.jna.platform.win32.Kernel32.INSTANCE.GetLastError()); // <- 5
        System.err.println(ph); // <- null
        if (ph != null) {
            byte[] filename = new byte[512];
            Psapi.INSTANCE.GetModuleBaseNameW(ph, new Pointer(0), filename, 512);

            try {
                Thread.sleep(1000);
            } catch (Exception ignore) {
            }

            System.err.println(Native.toString(filename));
            Kernel32.INSTANCE.CloseHandle(ph);
        }

    }

}

Answer 1

Calling OpenProcess with PROCESS_VM_READ means that you want to read the memory of that process. To do this, you need the SE_DEBUG_PRIVLEGE . Your application doesn't have that privilege which is why you are getting access denied.

Check the MSDN article for ReadProcessMemory . There is some community content on how to acquire that privilege.