Analysis by: Nikko Tamana
 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: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan 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: 74,240 bytes
Memory Resident: Yes
Initial Samples Received Date: 25 Nov 2013

Arrival Details

This Trojan 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 Trojan drops the following copies of itself into the affected system:

  • %System%\{random file name}.exe

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

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\bfsvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\bfsvc\Enum

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\bfsvc\Security

It adds the following registry entries as part of its installation routine:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\bfsvc
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\bfsvc
Start = "3"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\bfsvc
ErrorControl = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\bfsvc
ImagePath = "%System%\drivers\bfsvc.sys"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\bfsvc
DisplayName = "bfsvc Driver"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\bfsvc\Security
Security = "{hex values}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\bfsvc\Enum
Count = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\bfsvc\Enum
NextInstance = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\bfsvc\Enum
INITSTARTFAILED = "1"

Other Details

This Trojan connects to the following URL(s) to get the affected system's IP address:

  • http://checkip.dyndns.org/

It connects to the following possibly malicious URL:

  • http://lestari.{BLOCKED}rill.my/sbl/?c
  • http://lestari.{BLOCKED}rill.my/sbl/?o={OS Version},{IP Address},{random hex values}
  • http://lestari.{BLOCKED}rill.my/sbl/ls.tmp
  • http://lestari.{BLOCKED}rill.my/sbl/ls.tmp

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 10.432.04
FIRST VSAPI PATTERN DATE: 25 Nov 2013
VSAPI OPR PATTERN File: 10.433.00
VSAPI OPR PATTERN Date: 26 Nov 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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • bfsvc

Step 4

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