WORM_NITOL.I
Win32/ServStart.AC (ESET-NOD32); DDoS:Win32/Nitol (Microsoft)
Windows
Threat Type: Worm
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It executes commands from a remote malicious user, effectively compromising the affected system.
TECHNICAL DETAILS
Arrival Details
This worm 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 and executes the following files:
- %User Temp%\hrl{random}.tmp <-- also detected as WORM_NITOL.I, deleted afterwards
- %System%\{random}.exe <-- detected as WORM_NITOL.I, copy of hrl{random}.tmp
(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
It drops the following copies of itself into the affected system:
- %System%\hra33.dll
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
It adds the following mutexes to ensure that only one of its copies runs at any one time:
- National{random} <-- same as registered service name
Autostart Technique
This worm registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\National{random}
ImagePath = %System%\{random}.exe
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\National{random}
DisplayName = National{random} Instruments Domain Service
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\National{random}
Description = Provides{random} a domain server for NI security.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\National{random}
ObjectName = LocalSystem
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\National{random}\Security
Security = {hex value}
It registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry keys:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\National{random}
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\National{random}\Security
Backdoor Routine
This worm executes the following commands from a remote malicious user:
- Download and execute arbitrary files
It connects to the following URL(s) to send and receive commands from a remote malicious user:
- hxxp://www.{BLOCKED}y.cc/vip48.html
NOTES:
This worm drops a copy of itself in all folders in all physical and removable drives containing an .EXE file using the file name LPK.DLL.
It also connects to different URLs to download and execute a file based from the reply of the C&C.
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
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, and then 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\SYSTEM\CurrentControlSet\Services
- National{random 3 letters}
- National{random 3 letters}
Step 4
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_NITOL.I. 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.
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