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BKDR_POISON.BTT

September 06, 2013
 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:

1,009,880 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

06 Sep 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.

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\WinRAR SFX

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\AppCompatFlags\
Layers

It adds the following registry entries:

HKEY_CURRENT_USER\Software\WinRAR SFX
C%%WINDOWS%system32 = "%System%"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\AppCompatFlags\
Layers
%System%\crypt.exe = "~ RUNASADMIN"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\MD ServicesB1
Description = "Thank you"

Dropping Routine

This backdoor drops the following files:

  • __tmp_rar_sfx_access_check_60468
  • crypt.exe
  • adminreg.reg
  • admin.vbs
  • %Program Files%\Internet Explorer\Svcwtyh.exe

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

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

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
    • WinRAR SFX
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags
    • Layers

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\WinRAR SFX
    • C%%WINDOWS%system32 = "%System%"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers
    • %System%\crypt.exe = "~ RUNASADMIN"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\MD ServicesB1
    • Description = "Thank you"

Step 4

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_60468
  • crypt.exe
  • adminreg.reg
  • admin.vbs
  • %Program Files%\Internet Explorer\Svcwtyh.exe

Step 5

Scan your computer with your Trend Micro product to delete files detected as BKDR_POISON.BTT. 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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