arrow_back
search
close

BKDR_POISON.BUO

September 05, 2013
 Analysis by: Adrian Cofreros
 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:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


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:

61,440 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

30 Aug 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:

  • %Windows%\block.exe

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

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
PreviewTool

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
PreviewTool\Recent File List

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
PreviewTool\Settings

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{random}

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{random}
StubPath = "%Windows%\block.exe"

Other Details

This backdoor connects to the following possibly malicious URL:

  • https://{BLOCKED}a.{BLOCKED}a.com

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.256.05

FIRST VSAPI PATTERN DATE:

03 Sep 2013

VSAPI OPR PATTERN File:

10.257.00

VSAPI OPR PATTERN Date:

04 Sep 2013

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
    • Local AppWizard-Generated Applications
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
    • {random}

Step 4

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


Did this description help? Tell us how we did.