TROJ_SHARIK.AJA

August 25, 2017
 Analysis by: Rheniel Rhay Ramos
 ALIASES:

Backdoor.Win32.Androm.nokd (Kaspersky); TrojanDownloader:Win32/Dofoil.AC (Microsoft);

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet

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 connects to certain websites to send and receive information. It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

204,288 bytes

Memory Resident:

Yes

Initial Samples Received Date:

27 Jun 2017

Payload:

Connects to URLs/IPs

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.

Installation

This Trojan adds the following mutexes to ensure that only one of its copies runs at any one time:

  • hashed computer name and volume serial number

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

  • explorer.exe
  • created svchost.exe

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{installed program name in the system} = “%Application Data%\{random folder name}\{random file name}.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run
{installed program name in the system} = “%Application Data%\{random folder name}\{random file name}.exe"

It drops the following shortcut pointing to its copy in the User Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\{random1}.lnk

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

Other Details

This Trojan connects to the following URL(s) to check for an Internet connection:

  • http://www.bing.com

It connects to the following website to send and receive information:

  • http://{BLOCKED}erinborisinafrolova.ru
  • http://{BLOCKED}nformaciiimexanikiops.com
  • http://{BLOCKED}rnmayakinternacional.ru

It does the following:

  • It performs several checks before performing its malicious routines:
    • The following flags of its PEB structure must not indicate that it is being debugged:
      • IsDebugging
      • NtGlobalFlag
    • Module filename must not contain the string “sample"
    • Volume serial number should not be:
      • 0xCD1A40 (ThreatExpert)
      • 0x70144646 (Malwr)
    • Registry data under HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Disk\Enum must not contain the following strings:
      • qemu
      • virtual
      • vmware
      • xen
      • fffcce24 (VBox)
    • The following modules should not be loaded:
      • dbghelp
      • sbiedll
  • It terminates other programs related to process and network monitoring, and debugging.

It deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine:

9.850

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 value

[ 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\Windows\CurrentVersion\Run
    • {installed program name in the system} = “%Application Data%\{random folder name}\{random file name}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run
    • {installed program name in the system} = “%Application Data%\{random folder name}\{random file name}.exe"

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 Startup%\{random1}.lnk

Step 6

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

Step 7

Scan your computer with your Trend Micro product to delete files detected as TROJ_SHARIK.AJA. 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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