Using code signing ensures that any third-party libraries or DLLs are signed by a trusted source before they are loaded by the application. This method helps mitigate the risk of DLL injection by ensuring the integrity and origin of the code being executed. DLL injection attacks typically involve the introduction of an unauthorized DLL into the application's process space. Code signing does not prevent the presence of third-party DLLs but verifies their legitimacy. Digital certificates are used in conjunction with code signing, but they do not directly prevent DLL injection; they are part of the broader code signing validation process. Restricting admin privileges prevents unauthorized changes to system files and configurations but does not specifically target the risk of loading malicious DLLs. Sandboxing isolates the application but does not specifically verify the integrity of loaded DLLs.