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BKDR_LECNA.AW

August 20, 2013
 ALIASES:

BackDoor-FATG!4107484111AB (McAfee); Trojan-Downloader.Win32.Genome.dnlr (Kaspersky); Trojan.Win32.Generic.pak!cobra (Sunbelt)

 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:

36,864 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

18 May 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:

  • %Program Files%\Mozilla Firefox\bin\firefox.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).)

It creates the following folders:

  • %Program Files%\Mozilla Firefox
  • %Program Files%\Mozilla Firefox\bin

(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).)

Other System Modifications

This backdoor deletes the following files:

  • %Program Files%\Mozilla Firefox\bin\UpdateFirefox.exe
  • %Program Files%\Mozilla Firefox\bin\FirefoxPlug.exe
  • %Program Files%\Mozilla Firefox\bin\FirefoxVista.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).)

It adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\
CurrentListenInf

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
CurrentListenInf
lnk = "Np{jmmb!Gjsfgpy/mol"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
CurrentListenInf
hostid = "281"

Dropping Routine

This backdoor drops the following files:

  • %Common Startup%\Mozilla Firefox.lnk

(Note: %Common Startup% is the system's shared Startup folder, which is usually C:\Documents and Settings\All Users\Start Menu\Programs\Startup on Windows 2000, XP, and Server 2003.)

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://www.{BLOCKED}m.com/Forward-mci/Guest.txt
  • http://www.{BLOCKED}m.com/Forward-mci/applan.txt
  • http://www.{BLOCKED}m.com/Forward-mci/hostlistlan.txt
  • http://www.{BLOCKED}m.com/Forward-mci/verlan.txt
  • http://www.{BLOCKED}m.com/Forward-mci/SomeUpVerlan.txt

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_LOCAL_MACHINE\Software\Microsoft
    • CurrentListenInf

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\CurrentListenInf
    • lnk = "Np{jmmb!Gjsfgpy/mol"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\CurrentListenInf
    • hostid = "281"

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.
  • %Common Startup%\Mozilla Firefox.lnk

Step 5

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.
  • %Program Files%\Mozilla Firefox
  • %Program Files%\Mozilla Firefox\bin

Step 6

Scan your computer with your Trend Micro product to delete files detected as BKDR_LECNA.AW. 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.

Step 7

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %Program Files%\Mozilla Firefox\bin\UpdateFirefox.exe
  • %Program Files%\Mozilla Firefox\bin\FirefoxPlug.exe
  • %Program Files%\Mozilla Firefox\bin\FirefoxVista.exe


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