WORM_LAPKA.AI


 ALIASES:

DDoS:Win32/Nitol.A (Microsoft); Rootkit.Win32.Lapka.an (Kaspersky); Trojan.Lapka (Symantec)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This worm arrives by connecting affected removable drives to a system. It 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:

52,736 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

05 May 2014

Arrival Details

This worm arrives by connecting affected removable drives to a system.

It 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 worm drops the following files:

  • %Windows%\{random}.exe
  • %User Temp%\{random}.tmp

(Note: %Windows% is the Windows folder, which is usually C:\Windows.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It drops the following copies of itself into the affected system:

  • %System%\hra33.dll
  • %Desktop%\lpk.dll
  • %User Temp%\lpk.dll
  • %User Temp%\{random folder}\lpk.dll
  • %User Temp%\{random folder}\uesetup\lpk.dll

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Desktop on Windows Vista and 7.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It creates the following folders:

  • %User Temp%\{random folder}
  • %User Temp%\{random folder}\uesetup

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Other System Modifications

This worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_.NET_CLR

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\.Net CLR

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Hardware Profiles\Current\Software\
Microsoft\windows\CurrentVersion\
Internet Settings
ProxyEnable = "0"

(Note: The default value data of the said registry entry is "1" (if proxy is enabled in the system).)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Hardware Profiles\{number}\Software\
Microsoft\windows\CurrentVersion\
Internet Settings
ProxyEnable = "0"

(Note: The default value data of the said registry entry is "1" (if proxy is enabled in the system.)

Propagation

This worm drops the following copy of itself in all physical and removable drives:

  • {all drives except system root and folders except in the system root that have a file with .exe extension}\lpk.dll

Other Details

This worm connects to the following possibly malicious URL:

  • 1.{BLOCKED}m.com

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

10.776.04

FIRST VSAPI PATTERN DATE:

05 May 2014

VSAPI OPR PATTERN File:

10.777.00

VSAPI OPR PATTERN Date:

06 May 2014

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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\SYSTEM\CurrentControlSet\Enum\Root
    • LEGACY_.NET_CLR
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • .Net CLR

Step 5

Restore this modified 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\SYSTEM\CurrentControlSet\Hardware Profiles\Current\Software\Microsoft\windows\CurrentVersion\Internet Settings
    • From: ProxyEnable = "0"
      To: ProxyEnable = "1" (if proxy is enabled in the system)
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Hardware Profiles\{number}\Software\Microsoft\windows\CurrentVersion\Internet Settings
    • From: ProxyEnable = "0"
      To: ProxyEnable = "1" (if proxy is enabled in the system

Step 6

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.  
  • %User Temp%\{random folder}

Step 7

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%\{random}.exe
  • %User Temp%\{random}.tmp

Step 8

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


Did this description help? Tell us how we did.