ALIASES:

TrojanDropper:Win32/Small.CE (Microsoft); MultiDropper-CE (McAfee); Trojan Horse (Symantec); Trojan-Dropper.Win32.Joiner.bk (Kaspersky); BehavesLike.Win32.Malware.wsc (mx-v) (Sunbelt); ERROR (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.

  TECHNICAL DETAILS

File Size: 69,152 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 28 Dec 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.

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
putil = "%Windows%\~2.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
msreg.exe = "%Windows%\msreg.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Memory Check = "%Windows%\MemChk.exe"

Other System Modifications

This backdoor deletes the following files:

  • %Temp%\temp.dll

(Note: %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp.)

It adds the following registry keys:

HKEY_CURRENT_USER\SOFTWARE\Mirabilis\
ICQ\NewOwners

HKEY_LOCAL_MACHINE\SOFTWARE\Miranda

HKEY_LOCAL_MACHINE\SOFTWARE\Mirabilis\
ICQ\DefaultPrefs

HKEY_CURRENT_USER\SOFTWARE\Mirabilis\
ICQ\DefaultPrefs

HKEY_CURRENT_USER\SOFTWARE\RIT\
The Bat!

HKEY_CURRENT_USER\Identities\{341F68BA-C841-4200-A7B4-3D5CFF202166}\
SOFTWARE\Microsoft\Internet Account Manager\
Accounts

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
Trillian

HKEY_CURRENT_USER\Software\Far\
Plugins\FTP\Hosts

HKEY_CURRENT_USER\Software\Ghisler\
Windows Commander

HKEY_CURRENT_USER\Software\Ghisler\
Total Commander

HKEY_LOCAL_MACHINE\Software\Ghisler\
Windows Commander

HKEY_LOCAL_MACHINE\Software\Ghisler\
Total Commander

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
&RQ

Dropping Routine

This backdoor drops the following files:

  • %User Temp%\~1.exe
  • %User Temp%\~2.exe
  • %User Temp%\~3.exe
  • %User Temp%\~4.exe
  • %Windows%\msreg.exe
  • %System%\svchostc.exe
  • %System%\svchosts.exe
  • %Windows%\~2.exe
  • %Temp%\temp.dll
  • %Windows%\MemChk.exe

(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.. %Windows% is the Windows folder, which is usually C:\Windows.. %System% is the Windows system folder, which is usually C:\Windows\System32.. %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.300

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_CURRENT_USER\SOFTWARE\Mirabilis\ICQ
    • NewOwners
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • Miranda
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Mirabilis\ICQ
    • DefaultPrefs
  • In HKEY_CURRENT_USER\SOFTWARE\Mirabilis\ICQ
    • DefaultPrefs
  • In HKEY_CURRENT_USER\SOFTWARE\RIT
    • The Bat!
  • In HKEY_CURRENT_USER\Identities\{341F68BA-C841-4200-A7B4-3D5CFF202166}\SOFTWARE\Microsoft\Internet Account Manager
    • Accounts
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
    • Trillian
  • In HKEY_CURRENT_USER\Software\Far\Plugins\FTP
    • Hosts
  • In HKEY_CURRENT_USER\Software\Ghisler
    • Windows Commander
  • In HKEY_CURRENT_USER\Software\Ghisler
    • Total Commander
  • In HKEY_LOCAL_MACHINE\Software\Ghisler
    • Windows Commander
  • In HKEY_LOCAL_MACHINE\Software\Ghisler
    • Total Commander
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
    • &RQ

Step 4

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\Microsoft\Windows\CurrentVersion\Run
    • putil = "%Windows%\~2.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • msreg.exe = "%Windows%\msreg.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Memory Check = "%Windows%\MemChk.exe"

Step 5

Search and delete these components

[ Learn More ]
There may be some components 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%\~1.exe
  • %User Temp%\~2.exe
  • %User Temp%\~3.exe
  • %User Temp%\~4.exe
  • %Windows%\msreg.exe
  • %System%\svchostc.exe
  • %System%\svchosts.exe
  • %Windows%\~2.exe
  • %Temp%\temp.dll
  • %Windows%\MemChk.exe

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_BIFROSE.BG. 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 7

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.

  • %Temp%\temp.dll


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