BKDR_SMALL.NVZ
Microsoft: Trojan:Win32/Sisproc ; Kaspersky: Trojan.Win32.Genome.kufo
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Backdoor
Destructiveness: No
Encrypted: No
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 may be dropped by other malware.
It connects to a website to send and receive information.
It deletes the initially executed copy of itself.
TECHNICAL DETAILS
14,332 bytes
EXE
Yes
22 Sep 2010
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.
It may be dropped by the following malware:
- TROJ_MDROP.SME
Installation
This backdoor drops the following copies of itself into the affected system:
- %User Temp%\logs\sqlservr.exe
(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.)
It creates the following folders:
- %User Temp%\logs
(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.)
It adds the following mutexes to ensure that only one of its copies runs at any one time:
- milestone374.dyndns.org:80-1.20
It terminates the execution of the copy it initially executed and executes the copy it drops instead.
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
Load = %User Temp%\logs\sqlservr.exe
It drops the following file(s) in the Windows Startup folder to enable its automatic execution at every system startup:
- Update.bat - batch file which adds an autostart registry entry for the malware
Backdoor Routine
This backdoor connects to the following websites to send and receive information:
- {BLOCKED}one374.dyndns.org
- {BLOCKED}321.dyndns.org
Other Details
This backdoor deletes the initially executed copy of itself
NOTES:
It may gather the following information:
- OS Version
- ComputerName
- Information Virtual Memory
- UserName System
SOLUTION
8.900
Step 1
For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.
Step 2
Remove malware files dropped/downloaded by BKDR_SMALL.NVZ
- TROJ_MDROP.SME
Step 3
Identify and terminate files detected as BKDR_SMALL.NVZ
- If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
- If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.
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_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
- Load = %User Temp%\logs\sqlservr.exe
- Load = %User Temp%\logs\sqlservr.exe
Step 5
Search and delete this folder
Step 6
Search and delete this file
Step 7
Scan your computer with your Trend Micro product to delete files detected as BKDR_SMALL.NVZ. 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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