BKDR_FYNLOS.SMIA

 Analysis by: MarfelTi
 Modified by: Sabrina Lei Sioting

 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:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • 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 modifies certain registry entries to disable Security Center functions. Doing this allows this malware to execute its routines without being detected.

  TECHNICAL DETAILS

File Size:

674,304 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

13 Apr 2013

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:

  • %System%\Windupdt\winupdate.exe

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

It creates the following folders:

  • %System%\Windupdt

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

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
winupdater = "%System%\Windupdt\winupdate.exe"

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,%System%\Windupdt\winupdate.exe"

(Note: The default value data of the said registry entry is %System%\userinit.exe,.)

Other System Modifications

This backdoor adds the following registry keys as part of its installation routine:

HKEY_CURRENT_USER\Software\DC3_FEXEC

It modifies the following registry entries to disable Security Center functions:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
AntiVirusDisableNotify = "1"

(Note: The default value data of the said registry entry is 0.)

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}ount3.no-ip.org

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

8.236.06

FIRST VSAPI PATTERN DATE:

20 Jun 2011

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

Identify and delete files detected as BKDR_FYNLOS.SMIA using either the Startup Disk or Recovery Console

[ 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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

 
  • In HKEY_CURRENT_USER\Software
    • DC3_FEXEC

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
    • winupdater = "%System%\Windupdt\winupdate.exe"

Step 5

Restore this modified 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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Userinit = "%System%\userinit.exe,%System%\Windupdt\winupdate.exe"
      To: Userinit = %System%\userinit.exe,
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • From: AntiVirusDisableNotify = "1"
      To: AntiVirusDisableNotify = 0

Step 6

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.
  • %System%\Windupdt

Step 7

Scan your computer with your Trend Micro product to delete files detected as BKDR_FYNLOS.SMIA. 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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