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BKDR_SHOTODOR.AX

May 01, 2014
 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:

1,122,768 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

01 May 2014

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 creates the following folders:

  • %System Root%\Documents and Settings\Wilbert
  • %User Profile%\lnsu6ybvaf
  • %User Profile%\Windows\Fl9iw0ctGi

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

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\RunOnce
lnsu6ybvaf = "%User Profile%\lnsu6ybvaf\25968.vbs"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\SOFTWARE\Fl9iw0ctGi

HKEY_CURRENT_USER\SOFTWARE\1376

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\MediaResources\msvideo

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Fl9iw0ctGi
ServerStarted = "4/20/2014 23:12:17 PM"

HKEY_CURRENT_USER\Software\Fl9iw0ctGi
InstalledServer = "%Windows%\Microsoft.NET\Framework\v2.0.50727\RegSvcs.exe"

HKEY_CURRENT_USER\Software\1376
Mutex = "Fl9iw0ctGi"

HKEY_CURRENT_USER\Software\Fl9iw0ctGi
NewGroup = "ARAB"

HKEY_CURRENT_USER\Software\Fl9iw0ctGi
NewId = "4tharriva"

HKEY_CURRENT_USER\Software\Fl9iw0ctGi
FirstExecution = "20/04/2014 23:12:21"

Dropping Routine

This backdoor drops the following files:

  • __tmp_rar_sfx_access_check_12410046
  • jDPFTtdFXx.VAW
  • fFSGMortIqeV.exe
  • ogFqKRUgSIk.CVF
  • pYwxubMl.DEF
  • %User Startup%\start.lnk
  • %User Profile%\Fl9iw0ctGi\Fl9iw0ctGi.nfo
  • %User Profile%\Fl9iw0ctGi\Fl9iw0ctGi.svr

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}112.41

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
    • Fl9iw0ctGi
  • In HKEY_CURRENT_USER\SOFTWARE
    • 1376
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\MediaResources
    • msvideo

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\RunOnce
    • lnsu6ybvaf = "%User Profile%\lnsu6ybvaf\25968.vbs"
  • In HKEY_CURRENT_USER\Software\Fl9iw0ctGi
    • ServerStarted = "4/20/2014 23:12:17 PM"
  • In HKEY_CURRENT_USER\Software\Fl9iw0ctGi
    • InstalledServer = "%Windows%\Microsoft.NET\Framework\v2.0.50727\RegSvcs.exe"
  • In HKEY_CURRENT_USER\Software\1376
    • Mutex = "Fl9iw0ctGi"
  • In HKEY_CURRENT_USER\Software\Fl9iw0ctGi
    • NewGroup = "ARAB"
  • In HKEY_CURRENT_USER\Software\Fl9iw0ctGi
    • NewId = "4tharriva"
  • In HKEY_CURRENT_USER\Software\Fl9iw0ctGi
    • FirstExecution = "20/04/2014 23:12:21"

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.
  • __tmp_rar_sfx_access_check_12410046
  • jDPFTtdFXx.VAW
  • fFSGMortIqeV.exe
  • ogFqKRUgSIk.CVF
  • pYwxubMl.DEF
  • %User Startup%\start.lnk
  • %User Profile%\Fl9iw0ctGi\Fl9iw0ctGi.nfo
  • %User Profile%\Fl9iw0ctGi\Fl9iw0ctGi.svr

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.
  • %System Root%\Documents and Settings\Wilbert
  • %User Profile%\lnsu6ybvaf
  • %User Profile%\Windows\Fl9iw0ctGi

Step 7

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