Injector / loader component

Hunt Hypothesis

The detection identifies potential injector/loader components used by adversaries to load malicious payloads into a system, which may indicate initial compromise or persistence. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage threats before they escalate.

YARA Rule

rule Trojan_Win32_Plakpers
{

    meta:
        author = "Microsoft"
        description = "Injector / loader component"
        original_sample_sha1 = "fa083d744d278c6f4865f095cfd2feabee558056"
        unpacked_sample_sha1 = "3a678b5c9c46b5b87bfcb18306ed50fadfc6372e"
        activity_group = "Platinum"
        version = "1.0"
        last_modified = "2016-04-12"

    strings:
        $str1 = "MyFileMappingObject"
        $str2 = "[%.3u] %s %s %s [%s:" wide
        $str3 = "%s\\{%s}\\%s" wide

    condition:
        $str1 and $str2 and $str3
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

• Microsoft Defender for Endpoint — Custom indicators / advanced hunting
• Email Gateway — Attachment scanning
• File Share Monitoring — Periodic scanning of shared drives
• YARA CLI — Manual threat hunting on endpoints

This rule contains 3 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: Scheduled system maintenance using schtasks
  Description: A legitimate scheduled task runs a script that uses a loader or injector mechanism to execute maintenance scripts.
  Filter/Exclusion: process.parent_process_name == "schtasks.exe" or process.command_line_contains("schtasks")

• Scenario: Windows Update deployment using Group Policy
  Description: A Group Policy update process may use a loader or injector to deploy updates silently.
  Filter/Exclusion: process.parent_process_name == "gpupdate.exe" or process.command_line_contains("gpupdate")

• Scenario: Admin task using PowerShell with Invoke-Command
  Description: An administrator uses PowerShell to remotely invoke commands that may trigger a loader or injector pattern.
  Filter/Exclusion: process.parent_process_name == "powershell.exe" and process.command_line_contains("Invoke-Command")

• Scenario: Software deployment using SCCM (System Center Configuration Manager)
  Description: SCCM may use a loader or injector component to deploy software silently to endpoints.
  Filter/Exclusion: process.parent_process_name == "ccmexec.exe" or process.command_line_contains("ccmexec")

• Scenario: Debugging with Process Explorer or Procmon
  Description: A security analyst uses tools like Process Explorer or Procmon to inspect processes, which may trigger loader/injector patterns.
  Filter/Exclusion: process.parent_process_name == "procmon.exe" or process.parent_process_name == "procexp.exe"