Differences between Hook injection, Virtual memory injection, DLL injection, Direct injection

Hook injection: This technique allows the malware to intercept messages or function calls destined for the target application (e.g., the keyboard driver). By hooking the appropriate function, the keylogger can capture keystrokes before they are processed by the legitimate program.

Virtual memory injection: While technically possible, virtual memory injection is a more complex technique and might not be the most efficient way for a keylogger to achieve its goal.

DLL injection: DLL injection can be used by keyloggers, but it doesn't necessarily involve hooks. The injected DLL could contain the keylogging functionality itself.

Direct injection: Similar to virtual memory injection, directly injecting machine code is a more complex approach and might not be the preferred method for keyloggers compared to hook injection.

How Keyloggers Use Hook Injection:

Target Hooks: Keyloggers typically target hooks related to keyboard input, such as the WH_KEYBOARD_LL hook. This hook allows the malware to intercept messages containing information about every keystroke.

Capturing Keystrokes: Once the hook is established, the keylogger can capture the key data from the intercepted messages and potentially log them to a file or transmit them to a remote server.

Here are some additional points to consider:

Some keyloggers might combine techniques. For example, a keylogger might use DLL injection to load its core functionality and then use hook injection to intercept keystrokes.

Hook injection can also be used by other types of malware, not just keyloggers.

By understanding how hook injection works, security professionals can develop detection mechanisms and employ tools to monitor system hooks for suspicious activity.