BKDR_LECNA.AD
Trojan.Gen.2 (Symantec)
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.
TECHNICAL DETAILS
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:
- %Start Menu%\Programs\Opera 11.00 internal\BIN\opera.exe
(Note: %Start Menu% is the Start Menu folder, where it usually is C:\Documents and Settings\{user name}\Start Menu on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
It creates the following folders:
- %Start Menu%\Programs\Opera 11.00 internal
- %Start Menu%\Programs\Opera 11.00 internal\BIN
(Note: %Start Menu% is the Start Menu folder, where it usually is C:\Documents and Settings\{user name}\Start Menu on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
Other System Modifications
This backdoor deletes the following files:
- %Start Menu%\Programs\Opera 11.00 internal\BIN\KB985109.log
- %Common Startup%\Opera.lnk
- %Program Files%\Opera 11.00 internal\BIN\opera.exe
- %Start Menu%\Programs\Opera 11.00 internal\BIN\UpdateOpera.exe
- %Start Menu%\Programs\Opera 11.00 internal\BIN\OperaVista.exe
(Note: %Start Menu% is the Start Menu folder, where it usually is C:\Documents and Settings\{user name}\Start Menu on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %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.. %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 adds the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
CurrentNetInf
It adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
CurrentNetInf
lnk = "Pqfsb/mol"
HKEY_CURRENT_USER\Software\Microsoft\
CurrentNetInf
hostid = "78ca"
Dropping Routine
This backdoor drops the following files:
- %User Startup%\Opera.lnk
- %Start Menu%\Programs\Opera 11.00 internal\BIN\Temp.txt
- %Start Menu%\Programs\Opera 11.00 internal\BIN\OperaPlug.exe
(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.. %Start Menu% is the Start Menu folder, where it usually is C:\Documents and Settings\{user name}\Start Menu on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
Other Details
This backdoor connects to the following possibly malicious URL:
- {BLOCKED}1.138.41
- {BLOCKED}1.138.116
This report is generated via an automated analysis system.
SOLUTION
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
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_CURRENT_USER\Software\Microsoft
- CurrentNetInf
Step 3
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_CURRENT_USER\Software\Microsoft\CurrentNetInf
- lnk = "Pqfsb/mol"
- In HKEY_CURRENT_USER\Software\Microsoft\CurrentNetInf
- hostid = "78ca"
Step 4
Search and delete these components
- %User Startup%\Opera.lnk
- %Start Menu%\Programs\Opera 11.00 internal\BIN\Temp.txt
- %Start Menu%\Programs\Opera 11.00 internal\BIN\OperaPlug.exe
Step 5
Search and delete these folders
- %Start Menu%\Programs\Opera 11.00 internal
- %Start Menu%\Programs\Opera 11.00 internal\BIN
Step 6
Scan your computer with your Trend Micro product to delete files detected as BKDR_LECNA.AD. 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.
- %Start Menu%\Programs\Opera 11.00 internal\BIN\KB985109.log
- %Common Startup%\Opera.lnk
- %Program Files%\Opera 11.00 internal\BIN\opera.exe
- %Start Menu%\Programs\Opera 11.00 internal\BIN\UpdateOpera.exe
- %Start Menu%\Programs\Opera 11.00 internal\BIN\OperaVista.exe
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