Modify Existing Service
Windows service configuration information, including the file path to the service's executable or recovery programs/commands, is stored in the Registry. Service configurations can be modified using utilities such as sc.exe and Reg. Adversaries can modify an existing service to persist malware on a system by using system utilities or by using custom tools to interact with the Windows API. Use of existing services is a type of Masquerading that may make detection analysis more challenging. Modifying existing services may interrupt their functionality or may enable services that are disabled or otherwise not commonly used. Adversaries may also intentionally corrupt or kill services to execute malicious recovery programs/commands. (Citation: Twitter Service Recovery Nov 2017) (Citation: Microsoft Service Recovery Feb 2013)
Mitigations |
|
| Mitigation | Description |
|---|---|
| Audit |
Perform audits or scans of systems, permissions, insecure software, insecure configurations, etc. to identify potential weaknesses. |
| User Account Management |
Manage the creation, modification, use, and permissions associated to user accounts. |
| Modify Existing Service Mitigation |
Use auditing tools capable of detecting privilege and service abuse opportunities on systems within an enterprise and correct them. Limit privileges of user accounts and groups so that only authorized administrators can interact with service changes and service configurations. Toolkits like the PowerSploit framework contain the PowerUp modules that can be used to explore systems for Privilege Escalation weaknesses. (Citation: Powersploit) Identify and block potentially malicious software that may be executed through service abuse by using whitelisting (Citation: Beechey 2010) tools like AppLocker (Citation: Windows Commands JPCERT) (Citation: NSA MS AppLocker) that are capable of auditing and/or blocking unknown programs. |
Detection
Look for changes to service Registry entries that do not correlate with known software, patch cycles, etc. Changes to the binary path and the service startup type changed from manual or disabled to automatic, if it does not typically do so, may be suspicious. Tools such as Sysinternals Autoruns may also be used to detect system service changes that could be attempts at persistence. (Citation: TechNet Autoruns)
Service information is stored in the Registry at HKLM\SYSTEM\CurrentControlSet\Services.
Command-line invocation of tools capable of modifying services may be unusual, depending on how systems are typically used in a particular environment. Collect service utility execution and service binary path arguments used for analysis. Service binary paths may even be changed to execute cmd commands or scripts.
Look for abnormal process call trees from known services and for execution of other commands that could relate to Discovery or other adversary techniques. Services may also be modified through Windows system management tools such as Windows Management Instrumentation and PowerShell, so additional logging may need to be configured to gather the appropriate data.
References
- Russinovich, M. (2016, January 4). Autoruns for Windows v13.51. Retrieved June 6, 2016.
- Microsoft. (2013, February 22). Set up Recovery Actions to Take Place When a Service Fails. Retrieved April 9, 2018.
- The Cyber (@r0wdy_). (2017, November 30). Service Recovery Parameters. Retrieved April 9, 2018.
Связанные риски
Каталоги
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