BKDR_LECNA.CJ
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)
Windows
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
40,960 bytes
EXE
No
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
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
Step 3
Delete this registry key
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
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
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""
- From: forceguest = "0"
Step 6
Search and delete these components
- %Windows%\netscv.exe
- %Windows%\netsvc.exe
Step 7
Search and delete this folder
- %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
Did this description help? Tell us how we did.