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BKDR_KLOVBOT.E

January 08, 2015
 Analysis by: Michael John Marcos
 ALIASES:

TrojanDownloader:Win32/VB.TJ (Microsoft), Win32/Injector.KQO (ESET)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet

This backdoor may be unknowingly downloaded by a user while visiting malicious websites.

It executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size:

98,304 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

09 Nov 2011

Payload:

Connects to URLs/IPs, Compromises system security

Arrival Details

This backdoor may be unknowingly downloaded by a user while visiting malicious websites.

Installation

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

  • %Windows%\csrcs.exe

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • byvOlk

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Microsofts = %Windows%\csrcs.exe

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Adds or modifies the affected system's HOSTS files
  • Visit Website (Hidden) - visits url without user's knowledge
  • Download and Execute file
  • Extract stored credentials from affected system (e.g. Filezilla)
  • Navigate Website (visible) - visit url using the affected system's default web browser

It connects to the following websites to send and receive information:

  • http://{BLOCKED}ss.net/winupdate

It posts the following information to its command and control (C&C) server:

  • Logged-on Username
  • IP Address
  • Country
  • OS version
  • Date and Time

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

8.562.02

VSAPI OPR PATTERN File:

8.563.00

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 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\CurrentVersion\Run
    • Microsofts = %Windows%\csrcs.exe

Step 4

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.
  • %Windows%\csrcs.exe

Step 5

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