BKDR_FARFLI.AE

October 12, 2012
 ALIASES:

TrojanDropper:Win32/Farfli.E (Microsoft); Generic Dropper!1ok (McAfee); ERROR (Sunbelt); Dropped:Trojan.Generic.KDV.583247 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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 deletes itself after execution.

  TECHNICAL DETAILS

File Size:

449,536 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

04 Apr 2012

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 creates the following folders:

  • %Program Files%\Vrlx

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files.)

Other System Modifications

This backdoor deletes the following files:

  • %System%\syslog.dat
  • %Program Files%\Vrlx\Gqhgjmcfm.gif
  • %System Root%\Net-Temp.ini

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.. %Program Files% is the default Program Files folder, usually C:\Program Files.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\53155024

HKEY_LOCAL_MACHINE\SOFTWARE\53155024\
Parameters

HKEY_LOCAL_MACHINE\SOFTWARE\9855457

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\53155024\
Parameters
ServiceDll = "%Program Files%\Vrlx\Gqhgjmcfm.gif"

HKEY_LOCAL_MACHINE\SOFTWARE\9855457
imgsvc = "StiSvc,Mkknbt Tloqftjr Mpc"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\RemoteAccess\RouterManagers\
Ip
DLLPath = "%System Root%\1392500.dll"

(Note: The default value data of the said registry entry is {random values}.)

Dropping Routine

This backdoor drops the following files:

  • %System Root%\1392500.dll
  • %System Root%\NT_Path.jpg
  • %Program Files%\Vrlx\Gqhgjmcfm.gif

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %Program Files% is the default Program Files folder, usually C:\Program Files.)

Other Details

This backdoor deletes itself after execution.

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

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
    • 53155024
  • In HKEY_LOCAL_MACHINE\SOFTWARE\53155024
    • Parameters
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • 9855457

Step 3

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_LOCAL_MACHINE\SOFTWARE\53155024\Parameters
    • ServiceDll = "%Program Files%\Vrlx\Gqhgjmcfm.gif"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\9855457
    • imgsvc = "StiSvc,Mkknbt Tloqftjr Mpc"

Step 4

Restore this modified 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_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\RemoteAccess\RouterManagers\Ip
    • From: DLLPath = "%System Root%\1392500.dll"
      To: DLLPath = ""{random values}""

Step 5

Search and delete these files

[ Learn More ]
There may be some component 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.
  • %System Root%\1392500.dll
  • %System Root%\NT_Path.jpg
  • %Program Files%\Vrlx\Gqhgjmcfm.gif

Step 6

Search and delete this folder

[ 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%\Vrlx

Step 7

Scan your computer with your Trend Micro product to delete files detected as BKDR_FARFLI.AE. 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 8

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %System%\syslog.dat
  • %Program Files%\Vrlx\Gqhgjmcfm.gif
  • %System Root%\Net-Temp.ini


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