Summary of what the program really does

1. Masquerades as a Realtek audio component
   • Strings such as “Realtek Audio Driver2”, “rtkdrv2.exe”, “rtksys2.exe”.
   • Tries to run as a Windows service under the same benign-looking name.

2. Self-installation & persistence
   • Command-line options
   --install → copies itself and adds a Run key
   --systeminstall → installs itself as an auto-start service with  sc create "Realtek Audio Driver2" binPath= "<self>" start= auto
   • If the program is started without those options (e.g. by SCM) it calls StartServiceCtrlDispatcherA and enters its service code.

3. Registry Run-key persistence
   ShellExecuteW "reg" ADD HKCU\Software\Microsoft\Windows\CurrentVersion\Run /v "<service-name>" /d "<self-path>"

4. Drops and launches a secondary copy
   • Builds a path like %TEMP%\rtkdrv2.exe and starts it with CreateProcessW.
   • Keeps the new process alive and restarts it if it exits.

5. Single-instance enforcement & process tampering
   • Builds a global mutex named “Global%08X%08X”.
   • Walks every running process (CreateToolhelp32Snapshot / Process32First/Next)

   • If another copy holding that mutex is found, this instance terminates.
     • If a previous child process is still around it is force-killed with TerminateProcess.

6. Service-mode watchdog
   In service mode the parent waits 30 s, duplicates the mutex handle into the child, then blocks in WaitForSingleObject. When the child dies it either restarts it or removes the persisted artefacts.

7. No legitimate audio driver functionality
   Nothing in the code touches audio APIs or hardware. Its only purposes are installation, persistence, process control and self-defence.

8. Anti-analysis hints
   • Uses IsDebuggerPresent / GetSystemTimeAsFileTime entropy, custom checksum, etc.
   • Sets the process error-mode to hide serious faults.

Why it is malicious

• Disguises itself as a well-known vendor component.
• Gains SYSTEM-level persistence by creating a fake service.
• Creates Run-key and service entries without user consent.
• Drops and executes additional binaries.
• Force-terminates other processes and duplicates handles to evade detection.
• Performs no legitimate task advertised by its name.

There is nothing in the binary that provides user value; every action is oriented toward covert installation and survival. It therefore classifies as malicious software (a dropper / loader with watchdog functionality).

Recommended actions

1. Do NOT run it on a production system.
2. Remove the service “Realtek Audio Driver2” and associated Run key if already executed.
3. Delete any dropped files (rtkdrv2.exe, rtksys2.exe, updatea*.bin).
4. Restore from backup or re-image if the machine was exposed; further payloads may have been deployed.
5. Submit the sample to your AV/EDR vendor for signature coverage.*

In short: this binary is a loader that pretends to be a Realtek audio driver, installs itself as a service or via Run-key, spawns a copy of itself, and uses mutexes and process manipulation to stay resident. It is definitely malicious.

Incident Analysis Report
Sample SHA-256: fead0633975c6c08f5509a7bd5c34d29bfdcacd3da47562efbf33121726f77b0
Date: <insert date>
Analyst: <your name / team>

1. Executive Summary

The submitted executable is a malicious dropper/loader that masquerades as a “Realtek Audio Driver”.
Its sole purpose is to install itself persistently (service + Run-key), deploy a secondary payload (rtkdrv2.exe / rtksys2.exe), and maintain continuous execution through a watchdog loop. No legitimate audio-driver functionality is present.

Threat classification: Trojan / Loader (persistence & watchdog)
Risk: High – SYSTEM-level persistence, arbitrary payload execution.

2. Technical Details

File information • Type……. PE 32-bit executable (Windows)
• Size……. ≈ 100 KB (exact: see hash)
• Entry….. 0x401E61 (labelled “entry”)

Key behaviors A. Installation paths
– Command-line “--install” → Adds HKCU\…\Run key:
HKCU\Software\Microsoft\Windows\CurrentVersion\Run<Realtek Audio Driver2> = “<self>”
– Command-line “--systeminstall” → Creates auto-start service:
sc create "Realtek Audio Driver2" binPath= "<self>" start= auto
– Without parameters it registers with Service Control Manager and runs as a service.

B. Payload deployment
– Copies itself as “%TEMP%\rtkdrv2.exe” (or “rtksys2.exe”, “updatea*.bin”).
– Launches the copy with CreateProcessW and restarts it if it exits.*

C. Watchdog & single-instance control
– Creates global mutex “Global<rnd>” to mark running instance.
– Enumerates processes; if duplicate found it terminates that process or exits.
– Duplicates mutex handle into child process; parent waits 30 s, then monitors child forever.

D. Anti-analysis / stealth
– IsDebuggerPresent, error-mode suppression, checksum.
– Uses benign names and legitimate Windows tools (sc.exe, reg.exe, cmd.exe).

No interaction with audio APIs or legitimate driver frameworks was detected.

3. Indicators of Compromise (IoCs)

Files/paths
• %TEMP%\rtkdrv2.exe
• %TEMP%\rtksys2.exe
• %TEMP%\updatea.bin / updatea2.bin
• Original executable wherever executed

Registry
• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\“Realtek Audio Driver2”
Service
• “Realtek Audio Driver2” (display name) – ImagePath points to malicious exe

Mutex
• Global???????????????? (hex value changes each run)

Network
– None observed in static analysis (runtime traffic unknown).

4. Potential Impact

• Privilege escalation to SYSTEM via service install
• Automatic execution on every boot/login
• Ability to execute or download additional malware (secondary payload placeholder)
• Potential interference with running processes (TerminateProcess usage)

5. Recommendations

1. Immediate containment
   – Block/ quarantine the hash in AV/EDR and email/web gateways.
2. Eradication
   – Remove service “Realtek Audio Driver2” (sc delete), delete Run-key, delete dropped files.
3. Recovery
   – Reboot and verify no mutex-holding processes remain; re-scan system.
4. Detection engineering
   – Alert on creation of services or Run-keys with “Realtek Audio Driver” naming but non-signed binaries.
   – Hunt for mutex pattern “Global\????????????????”.
5. Further investigation
   – If executed, capture memory/traffic of “rtkdrv2.exe” to identify follow-on payloads.

6. Appendices

A. Strings of interest
“Realtek Audio Driver2” “rtkdrv2.exe” “ADD HKEY_CURRENT_USER\…Run”
“create "Realtek Audio Driver2" binPath= "%s"”
B. Relevant Windows API calls
StartServiceCtrlDispatcherA, CreateToolhelp32Snapshot, DuplicateHandle,
CreateMutexW/OpenMutexW, CreateProcessW, TerminateProcess, ShellExecute*
C. Full static call-graph and de-compiled functions available upon request.*

End of Report