T1556.008_network-provider-dll

T1556.008 Network Provider DLL

Sub-technique of: T1556

High-Level 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. 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.

Adversaries can configure a malicious network provider DLL to receive credentials from mpnotify.exe. 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.

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.

Kill Chain Phase

• Credential Access (TA0006)
• Defense Evasion (TA0005)
• Persistence (TA0003)

Platforms: Windows

What to Check

• Identify if Network Provider DLL technique is applicable to target environment
• Check Windows systems for indicators of Network Provider DLL
• Verify mitigations are bypassed or absent (3 known mitigations)
• Assess detection coverage (1 detection strategies)

How to Test

Manual Testing

1. Identify Attack Surface: Determine if the target environment is susceptible to Network Provider DLL by examining the target platforms (Windows).

2. Assess Existing Defenses: Review whether mitigations for T1556.008 are in place. If defenses are absent or misconfigured, this technique may be exploitable.

3. Execute Test: Use tools and methods described in the MITRE ATT&CK page and external references below.

Note: No Atomic Red Team tests available for this technique. See Atomic Red Team GitHub for updates.

Remediation Guide

M1024 Restrict Registry Permissions

Restrict Registry permissions to disallow the modification of sensitive Registry keys such as HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\NetworkProvider\Order.

M1047 Audit

Periodically review for new and unknown network provider DLLs within the Registry (HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\<NetworkProviderName>\NetworkProvider\ProviderPath).

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 corresponding service subkey pointing to a DLL at HKEY_LOCAL_MACHINE\SYSTEM\CurrentC ontrolSet\Services\<NetworkProviderName>\NetworkProvider.

M1028 Operating System Configuration

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.

Detection

Detect Network Provider DLL Registration and Credential Capture

Risk Assessment

CWE Categories

References

• NPPSPY - Huntress
• NPPSPY Video
• NPPSPY
• Network Provider API
• NPLogonNotify
• Atomic Red Team - T1556.008
• MITRE ATT&CK - T1556.008