BKDR_LECNA.CJ


 ALIASES:

Backdoor:Win32/Lecna.M!dha (Microsoft); BackDoor-CSB (McAfee); W32.Lecna.E (Symantec); Backdoor.Win32.Lecna.w (Kaspersky); Troj/Lecna-S (Sophos); Trojan.Win32.Generic!SB.0 (Sunbelt); Found Win32/DH{IIESEx4XAwgJD3wkIiU} (AVG)

 PLATFORM:

Windows

 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.

It disables Task Manager, Registry Editor, and Folder Options.

  TECHNICAL DETAILS

File Size:

40,960 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

12 May 2015

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%\Internet Exp1orer\IEXPLORE.EXE

(Note: %Program Files% is the Program Files folder, where it usually is C:\Program Files on all Windows operating system versions; C:\Program Files (x86) for 32-bit applications running on Windows 64-bit operating systems.)

It creates the following folders:

  • %Program Files%\Internet Exp1orer

(Note: %Program Files% is the Program Files folder, where it usually is C:\Program Files on all Windows operating system versions; C:\Program Files (x86) for 32-bit applications running on Windows 64-bit operating systems.)

Other System Modifications

This backdoor deletes the following files:

  • %Windows%\netsvcs.exe
  • %Temp%\scs4.tmp
  • %Temp%\scs7.tmp
  • %Temp%\scsB.tmp
  • %Temp%\scsE.tmp

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

It adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\
CurrentNetInf

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
CurrentNetInf
pid = "9c5382278766898cf2:99685557236fbf6154bdb"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
CurrentNetInf
hostid = "2138"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
CurrentNetInf
pid = "JFYQMPSF/FYF"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\Lsa
forceguest = "0"

(Note: The default value data of the said registry entry is 1.)

It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run
IEXPLORE.EXE = "%Program Files%\Internet Exp1orer\IEXPLORE.EXE"

Dropping Routine

This backdoor drops the following files:

  • %Windows%\netscv.exe
  • %Windows%\netsvc.exe

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

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}.229.25

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.750

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

Enable Registry Editor, Task Manager, and Folder options

[ Learn More ]
By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware.

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\Software\Microsoft
    • CurrentNetInf
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • Run

Step 4

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\CurrentNetInf
    • pid = "9c5382278766898cf2:99685557236fbf6154bdb"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\CurrentNetInf
    • hostid = "2138"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\CurrentNetInf
    • pid = "JFYQMPSF/FYF"

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Lsa
    • From: forceguest = "0"
      To: forceguest = ""1""

Step 6

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.
  • %Windows%\netscv.exe
  • %Windows%\netsvc.exe

Step 7

Search and delete this folder

[ 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%\Internet Exp1orer

Step 8

Scan your computer with your Trend Micro product to delete files detected as BKDR_LECNA.CJ. 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 9

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.

  • %Windows%\netsvcs.exe
  • %Temp%\scs4.tmp
  • %Temp%\scs7.tmp
  • %Temp%\scsB.tmp
  • %Temp%\scsE.tmp


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