Network Provider DLL
Network Provider DLL [T1556.008]
Information
Name: Network Provider DLL
ID: T1556.008
Technique: T1556
Introduction
Network Provider DLL (T1556.008) is a sub-technique within the MITRE ATT&CK framework categorized under Credential Access (T1556). Attackers exploit this method by leveraging malicious Dynamic Link Libraries (DLLs) registered as network providers. Network provider DLLs are legitimate Windows components that manage network connections and authentication processes. Adversaries abuse these DLLs to intercept user credentials, enabling persistent credential harvesting and facilitating lateral movement within compromised environments.
Deep Dive Into Technique
Network provider DLLs in Windows are used to manage authentication and connection requests to network resources. Legitimate network providers are registered in the Windows Registry under the following key:
Attackers exploiting this technique typically follow these steps:
DLL Creation and Deployment:
Craft a malicious DLL file that implements the required interfaces and functions for network providers, such as
NPLogonNotify,NPPasswordChangeNotify, and others.Place the malicious DLL into a directory accessible by the targeted system, usually within system directories (
C:\Windows\System32) to blend in with legitimate files.
Registry Modification:
Modify the registry key mentioned above to add the malicious DLL as a network provider. Specifically, attackers add the DLL's name to the registry value
ProviderOrder.Example registry modification:
Credential Interception:
Once installed and registered, the malicious DLL intercepts authentication requests, capturing plaintext credentials or hashes during user login attempts or network resource access.
Credentials harvested can be stored locally or exfiltrated to remote command-and-control (C2) servers.
Persistence and Stealth:
Leveraging network provider DLLs provides attackers persistent access to credentials across system reboots.
Malicious DLLs typically mimic legitimate DLL naming conventions and behaviors to evade detection.
When this Technique is Usually Used
Attackers commonly utilize Network Provider DLL techniques in various stages of the cyber kill chain, particularly in:
Credential Access Stage:
To harvest valid credentials from compromised systems, enabling lateral movement and privilege escalation within the network.
Persistence Stage:
Establishing long-term footholds by ensuring credential interception continues across system restarts, updates, or user logouts.
Lateral Movement Stage:
Using captured credentials to move laterally within the network environment, escalating privileges, and compromising additional hosts.
Advanced Persistent Threat (APT) Scenarios:
Highly sophisticated adversaries, including nation-state actors, frequently adopt this technique due to its stealthy nature and effectiveness in credential harvesting.
How this Technique is Usually Detected
Detection of malicious Network Provider DLLs requires proactive monitoring and robust defensive measures, including:
Registry Monitoring:
Continuously monitor and alert on modifications to the registry key:
Tools such as Sysmon, Event Log Forwarding, and Endpoint Detection and Response (EDR) solutions can detect and alert on suspicious registry changes.
DLL File Integrity Monitoring:
Implement file integrity monitoring (FIM) solutions to detect unauthorized DLL files added to system directories, particularly those named similarly to legitimate network provider DLLs.
Endpoint Detection and Response (EDR) Solutions:
EDR platforms can detect anomalous DLL loading behaviors, suspicious credential access patterns, and malicious network activity indicative of credential exfiltration.
Behavioral Analytics and Anomaly Detection:
Monitor for unusual authentication activities, unexpected credential usage, or abnormal login patterns that could indicate credential interception and misuse.
Indicators of Compromise (IoCs):
Suspicious DLL files appearing in system directories (e.g., unusual file names or unknown digital signatures).
Unusual modifications to the ProviderOrder registry key.
Unexpected outbound network traffic from systems, potentially indicating credential exfiltration activities.
Why it is Important to Detect This Technique
Early detection of Network Provider DLL attacks is critically important due to their severe potential impacts:
Credential Theft and Compromise:
Attackers gain continuous access to valid user credentials, enabling further compromise of sensitive systems, accounts, and data.
Persistent Access and Stealth:
Malicious DLLs registered as network providers often remain undetected for extended periods, providing adversaries persistent and stealthy credential harvesting capabilities.
Lateral Movement and Privilege Escalation:
Harvested credentials facilitate lateral movement across internal networks, allowing attackers to escalate privileges, compromise additional hosts, and access sensitive resources.
Data Theft and Breaches:
Persistent credential interception can lead to unauthorized access to critical data, intellectual property theft, and significant data breaches.
Compliance and Regulatory Risks:
Failure to detect and remediate such attacks promptly can result in compliance violations, regulatory fines, reputational damage, and loss of customer trust.
Examples
Real-world examples demonstrating the exploitation of Network Provider DLL techniques include:
APT10 (MenuPass Group):
APT10, a known Chinese threat actor group, has been observed leveraging malicious network provider DLLs to intercept credentials and maintain persistence within compromised networks.
They deployed malicious DLLs registered as network providers to silently capture user credentials during authentication events, enabling subsequent lateral movement and data exfiltration.
FIN7 (Carbanak Group):
FIN7 has utilized advanced credential harvesting techniques, including malicious network provider DLLs, to intercept credentials and persistently maintain access to targeted financial institutions.
Their malicious DLLs intercepted authentication requests, allowing FIN7 to escalate privileges and access sensitive financial systems.
TrickBot Malware:
TrickBot has been observed deploying modules that utilize malicious network provider DLLs to capture credentials from infected hosts.
This enabled TrickBot operators to expand their foothold within compromised networks, facilitating further attacks such as ransomware deployment (e.g., Ryuk ransomware).
Attack scenarios typically involve:
Deployment of malicious DLL files via phishing emails, watering hole attacks, or supply chain compromises.
Registry modifications executed through compromised administrative accounts or privilege escalation exploits.
Credential interception used to facilitate lateral movement, privilege escalation, and data theft.
Tools frequently leveraged alongside this technique include Cobalt Strike, Metasploit, and custom-built malware frameworks designed for stealthy credential harvesting and persistence.
Impacts of these attacks have included:
Significant financial losses due to unauthorized access and theft.
Intellectual property theft and espionage activities.
Prolonged persistence and stealthy compromise within organizational networks, causing extensive damage and remediation efforts.
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