Techniques
Sample rules
Detect Regsvcs with Network Connection
- source: splunk
- technicques:
- T1218.009
Description
The following analytic identifies instances of Regsvcs.exe establishing a network connection to a public IP address, excluding private IP ranges. This detection leverages Sysmon EventID 3 logs to monitor network connections initiated by Regsvcs.exe. This activity is significant as Regsvcs.exe, a legitimate Microsoft-signed binary, can be exploited to bypass application control mechanisms and establish remote Command and Control (C2) channels. If confirmed malicious, this behavior could allow an attacker to escalate privileges, persist in the environment, and exfiltrate sensitive data. Immediate investigation and remediation are recommended.
Detection logic
`sysmon` EventID=3 dest_ip!=10.0.0.0/8 dest_ip!=172.16.0.0/12 dest_ip!=192.168.0.0/16 process_name=regsvcs.exe
| stats count min(_time) as firstTime max(_time) as lastTime by dest, user, process_name, src_ip, dest_ip
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `detect_regsvcs_with_network_connection_filter`
Detect Regsvcs with No Command Line Arguments
- source: splunk
- technicques:
- T1218.009
Description
The following analytic detects instances of regsvcs.exe running without command line arguments. This behavior typically indicates process injection, where another process manipulates regsvcs.exe. The detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names, IDs, and command-line executions. This activity is significant as it may signal an attempt to evade detection and execute malicious code. If confirmed malicious, the attacker could achieve code execution, potentially leading to privilege escalation, persistence, or access to sensitive information.
Detection logic
| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes where `process_regsvcs` by _time span=1h Processes.process_id Processes.process_name Processes.dest Processes.user Processes.process_path Processes.process Processes.parent_process_name
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| regex process="(?i)(regsvcs\.exe.{0,4}$)"
| `detect_regsvcs_with_no_command_line_arguments_filter`