Potential REMCOS Trojan Execution

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Potential REMCOS Trojan Execution

Identifies known execution traces of the REMCOS Remote Access Trojan. Remcos RAT is used by attackers to perform actions on infected machines remotely.

Rule type: eql

Rule indices:

endgame-*
logs-endpoint.events.registry-*
logs-endpoint.events.file-*
logs-m365_defender.event-*
logs-sentinel_one_cloud_funnel.*
logs-system.security*
logs-windows.sysmon_operational-*
winlogbeat-*

Severity: high

Risk score: 73

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

Domain: Endpoint
OS: Windows
Use Case: Threat Detection
Tactic: Command and Control
Resources: Investigation Guide
Data Source: Elastic Endgame
Data Source: Elastic Defend
Data Source: Sysmon
Data Source: SentinelOne
Data Source: Microsoft Defender for Endpoint
Data Source: Windows Security Event Logs

Version: 1

Rule authors:

Elastic

Rule license: Elastic License v2

Investigation guide

edit

Triage and analysis

Investigating Potential REMCOS Trojan Execution

Remcos RAT is used by attackers to perform actions on infected machines remotely.

Possible investigation steps

Review the origin of the REMCOS file and the execution chain to identify the initial vector..
Examine if the process is set to persist in the affected system via scheduled task, Startup folder or Run key.
Check the network, files and child processes activity associated with the every suspicious process in the execution chain of REMCOS.
Correlate the event with other security alerts or logs from data sources like Elastic Defend or Microsoft Defender for Endpoint to gather additional context and identify any related malicious activities.

Response and remediation

Immediately isolate the affected system from the network to prevent further unauthorized access or lateral movement by the attacker.
Terminate any suspicious processes identified in the alert, such as PowerShell, cmd.exe, or other flagged executables, to halt any ongoing malicious activity.
Review and revoke any unauthorized user accounts or privileges that may have been created or modified using tools like net.exe or schtasks.exe.
Conduct a thorough scan of the affected system using endpoint protection tools to identify and remove any malware or unauthorized software installed by the attacker.
Restore the system from a known good backup if any critical system files or configurations have been altered or compromised.
Escalate the incident to the security operations center (SOC) or incident response team for further investigation and to determine if additional systems are affected.
Implement enhanced monitoring and logging for ScreenConnect and other remote access tools to detect similar activities in the future, ensuring that alerts are promptly reviewed and acted upon.

Rule query

edit

any where host.os.type == "windows" and
(
 (event.category == "file" and event.type == "deletion" and file.path like "C:\\Users\\*\\AppData\\Local\\Temp\\TH????.tmp") or

 (event.category == "file" and file.path : "?:\\Users\\*\\AppData\\Roaming\\remcos\\logs.dat") or

 (event.category == "registry" and
  registry.value : ("Remcos", "Rmc-??????", "licence") and
  registry.path : (
      "*\\Windows\\CurrentVersion\\Run\\Remcos",
      "*\\Windows\\CurrentVersion\\Run\\Rmc-??????",
      "*\\SOFTWARE\\Remcos-*\\licence",
      "*\\Software\\Rmc-??????\\licence"
  )
 )
)

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Command and Control
- ID: TA0011
- Reference URL: https://attack.mitre.org/tactics/TA0011/
Technique:
- Name: Remote Access Tools
- ID: T1219
- Reference URL: https://attack.mitre.org/techniques/T1219/

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