Analysis by: Christopher Daniel So

 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: 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. It connects to a website to send and receive information.

It logs a user's keystrokes to steal information.

  TECHNICAL DETAILS

File Size: 85,373 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 23 Apr 2014
Payload: Steals information, Compromises system security, 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 copies of itself into the affected system:

  • %Windows%\winieupdates\ieupdates.exe

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

It creates the following folders:

  • %Windows%\winieupdates

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

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{71C15375-874E-8E89-DB04-4ABE3438255E}
stubpath = "%Windows%\winieupdates\ieupdates.exe s"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\fxsdsdsd

HKEY_LOCAL_MACHINE\SOFTWARE\fxsdsdsd

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Download a file
  • Upload a file
  • Get file details (file size, last modified time)
  • Create a folder
  • Delete a folder
  • Open a file using ShellExecute
  • Execute a command line
  • Rename a file
  • Enumerate all windows and their process IDs
  • Close a window
  • Move a window to the foreground
  • Hide a window
  • Send keystrokes to a window
  • Send mouse events to a window
  • Terminate a process
  • Get display resolution
  • Upload contents of %Windows%\winieupdates\klog.dat
  • Capture screenshot or webcam image

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

It connects to the following websites to send and receive information:

  • {BLOCKED?}news.flnet.org:443

Dropping Routine

This backdoor drops the following file(s), which it uses for its keylogging routine:

  • %Windows%\winieupdates\klog.dat

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

Information Theft

This backdoor logs a user's keystrokes to steal information.

NOTES:
This malware is also capable of using the Tor network in communicating with its command-and-control server.

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 10.744.03
FIRST VSAPI PATTERN DATE: 23 Apr 2014
VSAPI OPR PATTERN File: 10.745.00
VSAPI OPR PATTERN Date: 24 Apr 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

Identify and terminate files detected as BKDR_BIFROSE.ZTBG-A

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

Delete these registry values

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator’s help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{71C15375-874E-8E89-DB04-4ABE3438255E}
    • stubpath = "%Windows%\winieupdates\ieupdates.exe s"

Step 5

Delete this registry key

[ Learn More ]

=Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator’s help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software
    • fxsdsdsd
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • fxsdsdsd

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.
  • %Windows%\winieupdates

Step 7

Scan your computer with your Trend Micro product to delete files detected as BKDR_BIFROSE.ZTBG-A. 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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