The following analytic detects when reg.exe modify registry keys that define Windows services and their configurations in Windows to detect potential threats earlier and mitigate the risks. This detection is made by a Splunk query that searches for specific keywords in the process name, parent process name, user, and process ID. This detection is important because it suggests that an attacker has modified the registry keys that define Windows services and their configurations, which can allow them to maintain access to the system and potentially move laterally within the network. It is a common technique used by attackers to gain persistence on a compromised system and its impact can lead to data theft, ransomware, or other damaging outcomes. False positives can occur since legitimate uses of reg.exe to modify registry keys for Windows services can also trigger this alert. Next steps include reviewing the process and user context of the reg.exe activity and identify any other concurrent processes that might be associated with the attack upon triage.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2023-04-27
- Author: Steven Dick, Teoderick Contreras, Splunk
- ID: 25212358-948e-11ec-ad47-acde48001122
Kill Chain Phase
- CIS 10
1 2 3 4 5 6 7 | tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Registry WHERE (Registry.registry_path="*\\SYSTEM\\CurrentControlSet\\Services*" Registry.registry_value_name = ImagePath) BY _time span=1h Registry.dest Registry.user Registry.registry_path Registry.registry_key_name Registry.registry_value_name Registry.registry_value_data Registry.process_guid | `drop_dm_object_name(Registry)` | where isnotnull(registry_value_data) | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_service_creation_using_registry_entry_filter`
The SPL above uses the following Macros:
windows_service_creation_using_registry_entry_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
To successfully implement this search, you need to be ingesting logs with the registry value name, registry path, and registry value data from your endpoints. If you are using Sysmon, you must have at least version 2.0 of the offical Sysmon TA. https://splunkbase.splunk.com/app/5709
Known False Positives
Third party tools may used this technique to create services but not so common.
Associated Analytic Story
- Active Directory Lateral Movement
- Suspicious Windows Registry Activities
- Windows Persistence Techniques
- Windows Registry Abuse
- Brute Ratel C4
|64.0||80||80||A Windows Service was created on a endpoint from $dest$ using a registry entry|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
source | version: 3