Analysis by: John Kevin Sanchez

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet

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

It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size: 128,023 bytes
File Type: EXE, DLL
Memory Resident: Yes
Initial Samples Received Date: 09 Mar 2015
Payload: Connects to URLs/IPs, Steals information

Arrival Details

This Backdoor 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 Backdoor drops the following copies of itself into the affected system:

  • %Program Files%\{random folder}\{random filename}.jpg

(Note: %Program Files% is the Program Files folder, where it usually is C:\Program Files on all Windows operating system versions; C:\Program Files (x86) for 32-bit applications running on Windows 64-bit operating systems.)

It creates the following folders:

  • %Program Files%\{random folder}

(Note: %Program Files% is the Program Files folder, where it usually is C:\Program Files on all Windows operating system versions; C:\Program Files (x86) for 32-bit applications running on Windows 64-bit operating systems.)

It is injected into the following processes running in memory:

  • svchost.exe

Autostart Technique

This Backdoor registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\{Random Key 1}\
Parameters
ServiceDll = "%Program Files%\{random folder}\{random filename}.jpg"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random key 2}\Parameters
ServiceDll = "%Program Files%\{random folder}\{random filename}.jpg"

Other System Modifications

This Backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\{Random Key 1}

HKEY_LOCAL_MACHINE\SOFTWARE\{Random Key 1}\
Parameters

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random key 2}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random key 2}\Parameters

It modifies the following registry key(s)/entry(ies) as part of its installation routine:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
imgsvc = "StiSvc {random key 2}"

Backdoor Routine

This Backdoor executes the following commands from a remote malicious user:

  • Download and execute files
  • Browses and manages files
  • Start/Stop services
  • Delete services
  • Enumerate running processes
  • Create processes
  • Get drive information
  • Get or change system information
  • Perform remote shell
  • View desktop
  • Creates screen captures
  • Record audio and webcam video
  • Log keyboard and mouse activities
  • Logs the user off
  • Manipulate registry
  • Get OS Version
  • Get Host Name
  • Shutdown Computer
  • Open/Close a printer - Print a document
  • Send stolen information

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • qq87459418.{BLOCKED}2.org
  • {BLOCKED}.{BLOCKED}.66.222
  • kr.{BLOCKED}i.kr
  • {BLOCKED}n900619.f3322.org

Information Theft

This Backdoor gathers the following data:

  • OS Version
  • Host Name
  • System Information
  • Drive Information
  • Keystrokes

  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, and then 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_LOCAL_MACHINE\SOFTWARE
    • {Random Key 1}
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • {random key 2}

Step 4

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
    • From: imgsvc = "StiSvc {random key 2}"
      To: imgsvc = "StiSvc"

Step 5

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.  
  • %Program Files%\{random folder}

Step 6

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