Description
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)
Platforms
Mitigations (3)
Restrict Registry PermissionsM1024
Restrict Registry permissions to disallow the modification of sensitive Registry keys such as HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\NetworkProvider\Order.
AuditM1047
Periodically review for new and unknown network provider DLLs within the Registry (HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\).
Ensure only valid network provider DLLs are registered. The name of these can be found in the Registry key at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\NetworkProvider\Order, and have correspondin
Operating System ConfigurationM1028
Starting in Windows 11 22H2, the EnableMPRNotifications policy can be disabled through Group Policy or through a configuration service provider to prevent Winlogon from sending credentials to network providers.(Citation: EnableMPRNotifications)
References
- Dray Agha. (2022, August 16). Cleartext Shenanigans: Gifting User Passwords to Adversaries With NPPSPY. Retrieved March 30, 2023.
- Grzegorz Tworek. (2021, December 14). How winlogon.exe shares the cleartext password with custom DLLs. Retrieved March 30, 2023.
- Grzegorz Tworek. (2021, December 15). NPPSpy. Retrieved March 30, 2023.
- Microsoft. (2021, January 7). Network Provider API. Retrieved March 30, 2023.
- Microsoft. (2021, October 21). NPLogonNotify function (npapi.h). Retrieved March 30, 2023.
Frequently Asked Questions
What is T1556.008 (Network Provider DLL)?
T1556.008 is a MITRE ATT&CK technique named 'Network Provider DLL'. It belongs to the Defense Impairment, Persistence, Credential Access tactic(s). 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 interf...
How can T1556.008 be detected?
Detection of T1556.008 (Network Provider DLL) typically involves monitoring system logs, network traffic, and endpoint telemetry. Use SIEM rules, EDR solutions, and behavioral analytics to identify suspicious activity associated with this technique.
What mitigations exist for T1556.008?
There are 3 documented mitigations for T1556.008. Key mitigations include: Restrict Registry Permissions, Audit, Operating System Configuration.
Which threat groups use T1556.008?
While specific threat group attribution may vary, this technique has been observed in various real-world attacks. Check the MITRE ATT&CK website for the latest threat intelligence.