Analysis by: Joselyn Canuela
ALIASES:

Trojan.Win32.Farfli.hl (Kaspersky), Backdoor:Win32/Zegost.DG (Microsoft), Found Luhe.Fiha.A (AVG)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware, 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: 157,208 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 04 Mar 2017
Payload: Steals information, Connects to URLs/IPs

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 files:

  • {Malware Path}\Myinfo.ini - contains install date information

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

  • cs999.xyl081217.com

Autostart Technique

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

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ghijkl Nopqrstu Wxy dsfasd
Type = "16"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ghijkl Nopqrstu Wxy dsfasd
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ghijkl Nopqrstu Wxy dsfasd
ErrorControl = "0"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ghijkl Nopqrstu Wxy dsfasd
DisplayName = "Ghijkl Nopqrstu Wxyabcde Ghij dsfsdf"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ghijkl Nopqrstu Wxy dsfasd
Security = "{hex values}"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ghijkl Nopqrstu Wxy dsfasd
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ghijkl Nopqrstu Wxy dsfasd
0 = "Root\LEGACY_GHIJKL_NOPQRSTU_WXY_DSFASD\0000"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ghijkl Nopqrstu Wxy dsfasd
Count = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ghijkl Nopqrstu Wxy dsfasd
NextInstance = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ghijkl Nopqrstu Wxy dsfasd
ImagePath = "{Malware Path and Filename}.exe"

Other System Modifications

This Backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ghijkl Nopqrstu Wxy dsfasd

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Enum\Root\LEGACY_GHIJKL_NOPQRSTU_WXY_DSFASD

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Enum\Root\LEGACY_GHIJKL_NOPQRSTU_WXY_DSFASD
NextInstance = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Enum\Root\LEGACY_GHIJKL_NOPQRSTU_WXY_DSFASD\
0000\Control
*NewlyCreated* = "0"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Enum\Root\LEGACY_GHIJKL_NOPQRSTU_WXY_DSFASD\
0000
Service = "Ghijkl Nopqrstu Wxy dsfasd"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Enum\Root\LEGACY_GHIJKL_NOPQRSTU_WXY_DSFASD\
0000
Legacy = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Enum\Root\LEGACY_GHIJKL_NOPQRSTU_WXY_DSFASD\
0000
ConfigFlags = "0"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Enum\Root\LEGACY_GHIJKL_NOPQRSTU_WXY_DSFASD\
0000
Class = "LegacyDriver"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Enum\Root\LEGACY_GHIJKL_NOPQRSTU_WXY_DSFASD\
0000
ClassGUID = "{GUID}"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Enum\Root\LEGACY_GHIJKL_NOPQRSTU_WXY_DSFASD\
0000
DeviceDesc = "Ghijkl Nopqrstu Wxyabcde Ghij dsfsdf"

Backdoor Routine

This Backdoor opens the following port(s) where it listens for remote commands:

  • TCP 2003

It executes the following commands from a remote malicious user:

  • Open/Close a printer - Print a document
  • Screen Capture
  • Get Connection Information
  • Get System Information
  • Send Stolen Information
  • Execute Shell Command
  • Download File

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

  • cs999.{BLOCKED}217.com

Information Theft

This Backdoor gathers the following data:

  • Host's Name
  • OS Version
  • Drive Information
  • Processor Information
  • Log keyboard and mouse activities

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.256.08
FIRST VSAPI PATTERN DATE: 04 Mar 2017
VSAPI OPR PATTERN File: 13.257.00
VSAPI OPR PATTERN Date: 05 Mar 2017

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

Disable this malware service

[ Learn More ]
  • Ghijkl Nopqrstu Wxy dsfasd

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Ghijkl Nopqrstu Wxy dsfasd
  • HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\Root\LEGACY_GHIJKL_NOPQRSTU_WXY_DSFASD

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.
  • {Malware Path}\Myinfo.ini

Step 6

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