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PUA.Win32.BSDownloader.AC

June 17, 2019
 Analysis by: Arvin Roi Macaraeg
 ALIASES:

W32/BrotherSoft.A.gen!Eldorado(FPROT);

 PLATFORM:

Windows

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

  • Threat Type: Potentially Unwanted Application

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This Potentially Unwanted Application 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:

673,984 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

14 Jun 2019

Arrival Details

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

Autostart Technique

This Potentially Unwanted Application adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
hao123Setting = "%User Temp%\bdg6E2E.exe http://jp.ha{BLOCKED}.com/?tn=brosoft_pay_hp_03_hao123_jp"

Other System Modifications

This Potentially Unwanted Application adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Baidu\
Hao123-jp\hao123desk
Desktop = "1"

HKEY_CURRENT_USER\Software\Baidu\
Hao123-jp\hao123desk
StartMenu = "1"

HKEY_CURRENT_USER\Software\Baidu\
Hao123-jp\hao123desk
QuickLaunch = "1"

HKEY_CURRENT_USER\Software\Baidu\
Hao123-jp\hao123desk
UseInstaller = "0"

HKEY_CURRENT_USER\Software\Baidu\
Hao123-jp\hao123desk
ToyPath = "%Application Data%\baidu\hao123-jp\hao123.1.0.0.1111.exe"

HKEY_CURRENT_USER\Software\Baidu\
Hao123-jp\hao123desk
BaiduTn = "tn=brosoft_pay_sc_03_hao123_jp"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
hao123desk-jp
DisplayIcon = ""%Application Data%\baidu\hao123-jp\hao123.1.0.0.1111.exe""

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
hao123desk-jp
DisplayName = "日本hao123ショートカット"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
hao123desk-jp
DisplayVersion = "1.0.0.1111"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
hao123desk-jp
HelpLink = "http://www.h{BLOCKED}.com/desk.html"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
hao123desk-jp
Publisher = "hao123"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
hao123desk-jp
UninstallString = ""%Application Data%\baidu\hao123-jp\hao123.1.0.0.1111.exe" -uninstall ""

HKEY_CURRENT_USER\Software\Baidu\
Hao123-jp\hao123desk
LaunchCount = "0"

HKEY_CURRENT_USER\Software\Baidu\
Hao123-jp\hao123desk
GUID = {GUID}

HKEY_CURRENT_USER\Software\Baidu\
Hao123-jp\hao123desk
NewBaiduTn = "tn=brosoft_pay_sc_03_hao123_jp"

Dropping Routine

This Potentially Unwanted Application drops the following files:

  • %Application Data%\baidu\hao123-jp\hao123.1.0.0.1111.exe
  • %User Temp%\bdg6E2E.exe
  • %User Temp%\nsf54D4.tmp\ns55B0.tmp
  • %User Temp%\nsf54D4.tmp\nsExec.dll
  • %Common Program%\日本hao123\Hao123.lnk
  • %Common Program%\日本hao123\hao123のアンインストール.lnk
  • {Malware path}\russia_pdf2_2_2_3_0_habit.zip.ob!

(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(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other Details

This Potentially Unwanted Application connects to the following possibly malicious URL:

  • http://downloaderfile.{BLOCKED}.com/download/bs_jp_hao123.html?n=PDF&icon=&soft=0&country=PH&ip=122.55.230.52
  • http://g.br{BLOCKED}ft.com/gads/downloader_down_ad.php

  SOLUTION

Minimum Scan Engine:

9.850

SSAPI PATTERN File:

2.185.00

SSAPI PATTERN Date:

20 Jun 2019

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 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

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_CURRENT_USER\Software\Baidu\Hao123-jp\hao123desk
    • Desktop = "1"
  • In HKEY_CURRENT_USER\Software\Baidu\Hao123-jp\hao123desk
    • StartMenu = "1"
  • In HKEY_CURRENT_USER\Software\Baidu\Hao123-jp\hao123desk
    • QuickLaunch = "1"
  • In HKEY_CURRENT_USER\Software\Baidu\Hao123-jp\hao123desk
    • UseInstaller = "0"
  • In HKEY_CURRENT_USER\Software\Baidu\Hao123-jp\hao123desk
    • ToyPath = "%Application Data%\baidu\hao123-jp\hao123.1.0.0.1111.exe"
  • In HKEY_CURRENT_USER\Software\Baidu\Hao123-jp\hao123desk
    • BaiduTn = "tn=brosoft_pay_sc_03_hao123_jp"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Uninstall\hao123desk-jp
    • DisplayIcon = ""%Application Data%\baidu\hao123-jp\hao123.1.0.0.1111.exe""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Uninstall\hao123desk-jp
    • DisplayName = "日本hao123ショートカット"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Uninstall\hao123desk-jp
    • DisplayVersion = "1.0.0.1111"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Uninstall\hao123desk-jp
    • HelpLink = "http://www.h{BLOCKED}3.com/desk.html"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Uninstall\hao123desk-jp
    • Publisher = "hao123"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Uninstall\hao123desk-jp
    • UninstallString = ""%Application Data%\baidu\hao123-jp\hao123.1.0.0.1111.exe" -uninstall ""
  • In HKEY_CURRENT_USER\Software\Baidu\Hao123-jp\hao123desk
    • LaunchCount = "0"
  • In HKEY_CURRENT_USER\Software\Baidu\Hao123-jp\hao123desk
    • GUID = "{GUID}""
  • In HKEY_CURRENT_USER\Software\Baidu\Hao123-jp\hao123desk
    • NewBaiduTn = "tn=brosoft_pay_sc_03_hao123_jp"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
    • hao123Setting = "%User Temp%\bdg6E2E.exe http://jp.h{BLOCKED}3.com/?tn=brosoft_pay_hp_03_hao123_jp"

Step 4

Search and delete these files

[ 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.
  • %Application Data%\baidu\hao123-jp\hao123.1.0.0.1111.exe
  • %User Temp%\bdg6E2E.exe
  • %User Temp%\nsf54D4.tmp\ns55B0.tmp
  • %User Temp%\nsf54D4.tmp\nsExec.dll
  • %Common Program%\日本hao123\Hao123.lnk
  • %Common Program%\日本hao123\hao123のアンインストール.lnk
  • {Malware path}\russia_pdf2_2_2_3_0_habit.zip.ob!

Step 5

Scan your computer with your Trend Micro product to delete files detected as PUA.Win32.BSDownloader.AC. 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 the following Trend Micro Support pages for more information:


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