Analysis by: Janus Agcaoili


Trojan-Dropper.Win32.VB.deol (Kaspersky), Trojan:Win32/Skeeyah.A!rfn (Microsoft)




  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes


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

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.

It terminates itself if it detects it is being run in a virtual environment.


File Size: 94,208 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 09 Oct 2015
Payload: Connects to URLs/IPs, 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 adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Global\{random}
  • Global\a0bp-{ID}

It injects threads into the following normal process(es):

  • explorer.exe
  • svchost.exe
  • csrss.exe
  • lsass.exe

Other System Modifications

This Trojan adds the following registry keys:


Other Details

This Trojan terminates itself if it detects it is being run in a virtual environment.

It does the following:

  • It connects to certain URLs to download possibly malicious files:
    • {URL}?img=1
    • {URL}?img=2
  • The downloaded files' codes will be saved as Data of the following Registry:
    • HKEY_USERS\{USER SID}\Software\Classes\CLSID\{ID}
    Reads the data in the following registry onto memory and execute it, thus exhibiting its malicious routine in the affected system:
    • HKEY_USERS\{USER SID}\Software\Classes\CLSID\{ID}
  • Creates copy of the following as %User Temp%\{random}.:
    • %System%\ActionQueue.dll
    • %System%\advapi32.dll
  • Injects codes to the copies created.
  • Terminates self if the following VM related-strings are found in the registry:
    • Software\Trusteer\Rapport
  • Terminates self if the malware's file name is of the following:
    • C:\TEST\sample.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It terminates itself if any of the following file(s) are present:

  • SysAnalyzer.exe


{ID} is malware generated based from the volume serial ID.

{URL} is based on data decrypted in the malware code. However, as of this writing, this particular sample does not contain the intended codes.

The malware checks the data of the following registry to determine whether or not to proceed in its routine to gain system-priviledges for the malware without user consent:


Minimum Scan Engine: 9.750
VSAPI OPR PATTERN File: 11.971.00
VSAPI OPR PATTERN Date: 10 Oct 2015

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_USERS\{USER SID}\Software\Classes\CLSID
    • {ID}

Step 5

Search and delete these files

[ 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}."

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_MOKER.A. 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.

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