Adversaries may register malicious network provider dynamic link libraries (DLLs) to capture cleartext user credentials during the authentication process. Network provider DLLs allow Windows to interface with specific network protocols and can also support add-on credential management functions.(Citation: Network Provider API) During the logon process, Winlogon (the interactive logon module) sends credentials to the local `mpnotify.exe` process via RPC. The `mpnotify.exe` process then shares the credentials in cleartext with registered credential managers when notifying that a logon event is happening.(Citation: NPPSPY - Huntress)(Citation: NPPSPY Video)(Citation: NPLogonNotify) 

Adversaries can configure a malicious network provider DLL to receive credentials from `mpnotify.exe`.(Citation: NPPSPY) Once installed as a credential manager (via the Registry), a malicious DLL can receive and save credentials each time a user logs onto a Windows workstation or domain via the `NPLogonNotify()` function.(Citation: NPLogonNotify)

Adversaries may target planting malicious network provider DLLs on systems known to have increased logon activity and/or administrator logon activity, such as servers and domain controllers.(Citation: NPPSPY - Huntress)
Network Provider DLL
source_name: mitre-attack  url: https://attack.mitre.org/techniques/T1556/008  external_id: T1556.008     source_name: NPPSPY - Huntress  description:  Dray Agha. (2022, August 16). Cleartext Shenanigans: Gifting User Passwords to Adversaries With NPPSPY. Retrieved March 30, 2023.  url: https://www.huntress.com/blog/cleartext-shenanigans-gifting-user-passwords-to-adversaries-with-nppspy     source_name: NPPSPY Video  description: Grzegorz Tworek. (2021, December 14). How winlogon.exe shares the cleartext password with custom DLLs. Retrieved March 30, 2023.  url: https://www.youtube.com/watch?v=ggY3srD9dYs     source_name: NPPSPY  description: Grzegorz Tworek. (2021, December 15). NPPSpy. Retrieved March 30, 2023.  url: https://github.com/gtworek/PSBits/tree/master/PasswordStealing/NPPSpy     source_name: Network Provider API  description: Microsoft. (2021, January 7). Network Provider API. Retrieved March 30, 2023.  url: https://learn.microsoft.com/en-us/windows/win32/secauthn/network-provider-api     source_name: NPLogonNotify  description: Microsoft. (2021, October 21). NPLogonNotify function (npapi.h). Retrieved March 30, 2023.  url: https://learn.microsoft.com/en-us/windows/win32/api/npapi/nf-npapi-nplogonnotify     