## Triage and analysis

### Investigating Remotely Started Services via RPC

The Service Control Manager Remote Protocol is a client/server protocol used for configuring and controlling service
programs running on a remote computer. A remote service management session begins with the client initiating the
connection request to the server. If the server grants the request, the connection is established. The client can then
make multiple requests to modify, query the configuration, or start and stop services on the server by using the same
session until the session is terminated.

This rule detects the remote creation or start of a service by correlating a `services.exe` network connection and the
spawn of a child process.

#### Possible investigation steps

- Review login events (e.g., 4624) in the alert timeframe to identify the account used to perform this action. Use the
`source.address` field to help identify the source system.
- Review network events from the source system using the source port identified on the alert and try to identify the
program used to initiate the action.
- Investigate the process execution chain (parent process tree) for unknown processes. Examine their executable files
for prevalence, whether they are located in expected locations, and if they are signed with valid digital signatures.
- Investigate any abnormal behavior by the subject process such as network connections, registry or file modifications,
and any spawned child processes.
- Investigate other alerts associated with the user/host during the past 48 hours.
- Validate if the activity is not related to planned patches, updates, network administrator activity, or legitimate
software installations.
- Retrieve the process executable and determine if it is malicious:
  - Use a private sandboxed malware analysis system to perform analysis.
    - Observe and collect information about the following activities:
      - Attempts to contact external domains and addresses.
      - File and registry access, modification, and creation activities.
      - Service creation and launch activities.
      - Scheduled task creation.
  - Use the PowerShell `Get-FileHash` cmdlet to get the files' SHA-256 hash values.
    - Search for the existence and reputation of the hashes in resources like VirusTotal, Hybrid-Analysis, CISCO Talos, Any.run, etc.

### False positive analysis

- Remote management software like SCCM may trigger this rule. If noisy on your environment, consider adding exceptions.

### Response and remediation

- Initiate the incident response process based on the outcome of the triage.
- Isolate the involved hosts to prevent further post-compromise behavior.
- If the triage identified malware, search the environment for additional compromised hosts.
  - Implement temporary network rules, procedures, and segmentation to contain the malware.
  - Stop suspicious processes.
  - Immediately block the identified indicators of compromise (IoCs).
  - Inspect the affected systems for additional malware backdoors like reverse shells, reverse proxies, or droppers that
  attackers could use to reinfect the system.
- Remove and block malicious artifacts identified during triage.
- Investigate credential exposure on systems compromised or used by the attacker to ensure all compromised accounts are
identified. Reset passwords for these accounts and other potentially compromised credentials, such as email, business
systems, and web services.
- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and
malware components.
- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
- Using the incident response data, update logging and audit policies to improve the mean time to detect (MTTD) and the
mean time to respond (MTTR).