Time Providers

Time Providers [T1547.003]

Information

• Name: Time Providers

• ID: T1547.003

• Tactics: TA0003, TA0004

• Technique: T1547

Introduction

Time Providers (T1547.003) is a sub-technique within the MITRE ATT&CK framework under the "Boot or Logon Autostart Execution" technique (T1547). Attackers leverage this sub-technique to establish persistence and execute malicious payloads by registering a malicious DLL as a Windows Time Service provider. Once configured, the malicious DLL is loaded and executed automatically when the Windows Time Service (W32Time) starts, providing attackers with a stealthy and persistent foothold in compromised environments.

Deep Dive Into Technique

The Windows Time Service (W32Time) is responsible for synchronizing time across systems within Active Directory domains and standalone Windows systems. It supports custom time providers, implemented as DLL files, that can extend or replace the default time synchronization functionality.

Attackers exploit this capability by:

• Creating or modifying registry keys to register a malicious DLL as a custom time provider.

• Typically placing the malicious DLL in a location accessible by the Windows Time Service (e.g., system directories such as %SystemRoot%\System32\).

• Restarting or waiting for the Windows Time Service to start, triggering the loading and execution of the malicious DLL.

Registry keys commonly targeted by attackers include:

• HKLM\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\

Attackers may configure specific subkeys under this path, such as:

• NtpClient

• NtpServer

These subkeys contain values like:

• DllName: Specifies the DLL to load.

• Enabled: Indicates whether the time provider is active (set to 1).

Once configured, every time the W32Time service starts, the malicious DLL is loaded into memory and executed, providing attackers persistent execution without relying on more obvious startup mechanisms.

When this Technique is Usually Used

Attackers commonly utilize the Time Providers technique at several stages of an intrusion, primarily to maintain persistence and stealth within compromised environments. Typical scenarios include:

• Post-exploitation persistence: After initial compromise, attackers establish long-term persistence through legitimate Windows services.

• Privilege escalation scenarios: Attackers who have gained administrative privileges may use this technique to ensure continued access, even after reboots or system updates.

• Advanced persistent threats (APTs): Sophisticated threat actors prefer subtle persistence methods, such as Time Providers, to evade detection and remain hidden for extended periods.

• Situations where more obvious persistence mechanisms (e.g., scheduled tasks, startup folders, registry run keys) are closely monitored by defenders, prompting attackers to leverage less commonly monitored methods.

How this Technique is Usually Detected

Detection of malicious Time Providers persistence mechanisms can be challenging but achievable through vigilant monitoring and proactive configuration management. Effective detection methods include:

• Monitoring registry modifications:

  • Track changes to registry keys under HKLM\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\.

  • Alert on new or modified DllName and Enabled values.

• Auditing DLL loads by the Windows Time Service:

  • Utilize tools like Sysmon, configured to log DLL loads (Event ID 7).

  • Identify unusual or unexpected DLLs loaded by svchost.exe processes hosting W32Time.

• Endpoint detection and response (EDR) solutions:

  • EDR platforms may detect suspicious DLL behavior or unusual service interactions.

• Analyzing system logs:

  • Regularly review Windows event logs for unexpected W32Time service restarts or errors.

• File integrity monitoring (FIM):

  • Monitor critical system directories (%SystemRoot%\System32\) for new or modified DLL files.

• Indicators of compromise (IoCs) to look for:

  • Unrecognized DLL files in system directories.

  • Suspicious registry entries referencing unknown DLLs.

  • Unusual outbound network connections initiated by the Windows Time Service process.

Why it is Important to Detect This Technique

Early detection of malicious Time Providers persistence is critical due to its potential severe impacts and stealthy nature. Key reasons include:

• Persistent foothold:

  • Attackers maintain long-term, stealthy access, allowing them to escalate privileges, move laterally, and exfiltrate sensitive data.

• Difficulty in detection:

  • Legitimate services like W32Time rarely raise suspicion, enabling attackers to evade standard detection mechanisms.

• Potential privilege escalation:

  • Malicious DLLs loaded by system-level processes may execute with elevated privileges, enabling further compromise of the system and network.

• Stability and reliability threats:

  • Malicious DLLs may destabilize critical system services, leading to system crashes, downtime, or degraded performance.

• Data exfiltration and espionage:

  • Attackers may leverage persistent access to exfiltrate sensitive data, intellectual property, or personally identifiable information (PII).

• Compliance and regulatory risks:

  • Undetected persistence mechanisms may violate compliance standards, leading to regulatory penalties or loss of customer trust.

Examples

Real-world examples and scenarios involving malicious use of Time Providers include:

• APT29 (Cozy Bear):

  • Russian threat actor known to leverage Time Providers for persistence.

  • Registered malicious DLLs under the W32Time service to maintain stealthy, persistent access to compromised networks.

  • Utilized this technique to evade detection while conducting espionage activities and data exfiltration.

• Proof-of-Concept Tools and Research:

  • Security researchers have demonstrated this technique publicly through proof-of-concept (PoC) code, showcasing how attackers could leverage Time Providers.

  • Tools such as "Atomic Red Team" include tests simulating malicious Time Providers usage, allowing defenders to validate detection capabilities.

• Hypothetical Attack Scenario:

  • An attacker gains initial access via phishing or vulnerability exploitation.

  • After privilege escalation, the attacker registers a malicious DLL as a W32Time provider.

  • The DLL executes malicious payloads, communicates with command-and-control (C2) servers, and ensures persistent access even after system restarts.

  • Persistent access enables long-term espionage, lateral movement, and data exfiltration.

These examples highlight the practical use of Time Providers as a stealthy persistence mechanism by advanced attackers and underscore the importance of robust detection and mitigation strategies.