Analysis by: Vincent Martin Hermosura
ALIASES:

RDN/Generic PWS.y!b2q (Mcafee), Trojan.Win32.Generic!BT (Sunbelt), TR/Symmi.43093 (Antivir), W32/Banker.ABAG!tr.spy (Fortinet), Trojan-Dropper.Agent (Ikarus), a variant of Win32/Spy.Banker.ABAG trojan, a variant of Win32/Spy.Banker.ABAG trojan (Esset), Trj/Chgt.C (Panda), is suspected of Trojan.Downloader.gen.h (Vba32)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

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.

  TECHNICAL DETAILS

File Size: 482,816 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 22 Aug 2014
Payload: Connects to URLs/IPs, Downloads files

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:

  • %User Temp%\aviso.txt

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It creates the following folders:

  • %Application Data%\Google\Chrome\User Data\Default\Extensions\{random characters 1}
  • %Application Data%\Google\Chrome\User Data\Default\Extensions\{random characters 1}\1.0_0
  • %Application Data%\Google\Chrome\User Data\Default\Extensions\{random characters 1}\1.0_0\img
  • %Application Data%\Google\Chrome\User Data\Default\Extensions\{random characters 2}
  • %Application Data%\Google\Chrome\User Data\Default\Extensions\{random characters 3}

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

Backdoor Routine

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

  • http://{BLOCKED}.{BLOCKED}.203.163/rename/00003/notify.php

Download Routine

This backdoor connects to the following URL(s) to download its component file(s):

  • http://{BLOCKED}.{BLOCKED}4.com/pluginchrome.zip - It saves the downloaded file as %Application Data%\Google\Chrome\User Data\Default\pluginchrome.zip - detected as BREX_QULKONWI.K

NOTES:

This backdoor executes %System%\ping.exe -n 1 g.{BLOCKED}4.com to check for connection. It drops and extracts %Application Data%\Google\Chrome\User Data\Default\pluginchrome.zip into the folder %Application Data%\Google\Chrome\User Data\Default\Extensions\{random characters 1}\1.0_0, which contains the following files/components:

  • getPagesSource.js
  • img\flash128.png
  • img\flash48.png
  • img\Thumbs.db
  • manifest.json
  • popup.html
  • popup.js

It may use the following backdoor commands:

  • BBABORT
  • BBALL
  • BBCANCEL
  • BBCLOSE
  • BBHELP
  • BBIGNORE
  • BBNO
  • BBOK
  • BBRETRY
  • BBYES
  • CDROM
  • CLOSEDFOLDER
  • CURRENTFOLDER
  • DLGTEMPLATE
  • DVCLAL
  • EXECUTABLE
  • FLOPPY
  • HARD
  • KNOWNFILE
  • NETWORK
  • OPENFOLDER
  • PACKAGEINFO
  • PREVIEWGLYPH
  • RAM
  • TFORM1
  • UNKNOWNFILE

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 11.110.02
FIRST VSAPI PATTERN DATE: 26 Aug 2014
VSAPI OPR PATTERN File: 11.111.00
VSAPI OPR PATTERN Date: 26 Aug 2014

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

Remove grayware/spyware files dropped/downloaded by BKDR_QULKONWI.K

    • BREX_QULKONWI.K

Step 4

Restart in Safe Mode

[ Learn More ]

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 Temp%\aviso.txt

Step 6

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.
  • %Application Data%\Google\Chrome\User Data\Default\Extensions\{random characters 1}
  • %Application Data%\Google\Chrome\User Data\Default\Extensions\{random characters 2}
  • %Application Data%\Google\Chrome\User Data\Default\Extensions\{random characters 3}

Step 7

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

The following created files/folders/registry keys/registry entries cannot be identified by the user since there are no reference values in the created key. The only way it can be identified is by comparing the present system information with a backup. Note that the said components do not have to be deleted since it won't be harmful to the system.

  • %Application Data%\Google\Chrome\User Data\Default\Extensions\{random characters 1}


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