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BKDR_FARFLI.XXZF

May 17, 2017
 Modified by: Byron Jon Gelera
 ALIASES:

Win32/Farfli.BGG (ESET-NOD32)

 PLATFORM:

Windows

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

  • 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:

536,576 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

10 May 2017

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%\Windows NT\winlogin.exe

(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.)

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\SYSTEM\CurrentControlSet\
Services\Microsoft .NET3
ImagePath = "%Program Files%\Windows NT\winlogin.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Microsoft .NET3
DisplayName = "Microsoft .NET Framework NGEN v2.0.5273"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Microsoft .NET3
Description = "Microsoft .NET Framework NGEN"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Microsoft .NET3
ConnectGroup = "ĬÈÏ·Ö×é"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Microsoft .NET3
ErrorControl = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Microsoft .NET3
MarkTime = {Date of malware execution}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Microsoft .NET3
ObjectName = LocalSystem

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Microsoft .NET3
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Microsoft .NET3
Type = "272"

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Microsoft .NET3

Other Details

This Backdoor connects to the following possibly malicious URL:

  • http://users.{BLOCKED}e.qq.com/fcg-bin/cgi_get_portrait.fcg?uins=450318992
  • {BLOCKED}9.110.67
  • {BLOCKED}30.86
  • {BLOCKED}3.210.212

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.398.04

FIRST VSAPI PATTERN DATE:

11 May 2017

VSAPI OPR PATTERN File:

13.399.00

VSAPI OPR PATTERN Date:

12 May 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

Restart in Safe Mode

[ Learn More ]

Step 3

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\SYSTEM\CurrentControlSet\ Services
    • Microsoft .NET3

Step 4

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