Analysis by: Rika Joi Gregorio




  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes


Infection Channel: Downloaded from the Internet, Dropped by other malware

This is one of the Trend Micro detections on the recent Stegoloader malware that affected healthcare organizations in North America. Steganography is a technique where malicious codes are embedded in image files to avoid detection.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

As of this writing, the said sites are inaccessible.

It connects to certain websites to send and receive information. It deletes itself after execution.


File Size: 475,136 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 27 May 2015
Payload: Connects to URLs/IPs, Steals information, Downloads files

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.


This Trojan drops the following files:

  • %User Temp%\~{random digits}.tmp - contains system information

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, and 8.)

It injects codes into the following process(es):

  • explorer.exe

Other System Modifications

This Trojan adds the following registry keys:


Download Routine

This Trojan accesses the following websites to download files:

  • http://{BLOCKED}
  • http://{BLOCKED}

As of this writing, the said sites are inaccessible.

Information Theft

This Trojan gathers the following data:

  • OS Version
  • Computer Name
  • Host Name
  • Running process

Other Details

This Trojan connects to the following website to send and receive information:

  • http://{BLOCKED}.{BLOCKED}.166.33/report_N_0013_{hex value}_{report status}

It deletes itself after execution.


The term {report status} may be any of the following:

  • already_active
  • already_ok
  • crc_ok
  • except
  • except_detail_
  • executed_ok
  • finished
  • gdiplus_not_ok
  • gdiplus_ok
  • image_not_ok
  • image_ok
  • image_size_not_ok
  • image_size_ok
  • image_type_not_ok
  • image_type_ok
  • mark_already
  • mark_not_setted
  • mark_ok
  • mark_setted
  • page_err
  • page_ok
  • payload_executed
  • payload_file_delete_ok
  • payload_file_name_ok
  • payload_file_run_ok
  • payload_file_wait_ok
  • payload_file_write_ok
  • payload_mem_not_ok
  • payload_mem_ok
  • payload_no_ok
  • payload_ok
  • payload_size_ok
  • payload_type_bad
  • payload_type_exe
  • payload_type_exe_wait_del
  • payload_type_shell
  • process_
  • started_ext_
  • step_0
  • step_1
  • step_2
  • step_3
  • step_4
  • watch2_err_1

It terminates itself if any of the conditions are met:

  • If any of the following processes is present in the system:
    • aswVBoxClient.exe
    • PEiD.exe
    • SandboxieDcomLaunch.exe
  • If the following registry is present:
    • HKEY_CURRENT_USER\Software\Wine

This malware relies on steganography to evade detection. It connects to specific URLs to download a stock image, where majority of its routines are embedded. It then extracts the following from the downloaded image:

  • Arbitrary code
  • List of URLs to be accessed


Minimum Scan Engine: 9.750

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft
    • EventSubsystem

Step 5

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %User Temp%\~{random digits}.tmp

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_GATAK.SMJV. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Did this description help? Tell us how we did.