BKDR_NITOL.UIQ
DDoS:Win32/Nitol.A (Microsoft); Troj/Dloadr-DNE (Sophos); Trojan.Win32.Nitol.b (v) (Sunbelt); Trojan horse DoS.DPT (AVG)
Windows 2000, Windows XP, Windows Server 2003
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:
- %User Profile%\Æô¶¯\Bf.exe
- %System Root%\Users\Administrator\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup\Bf.exe
(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Avast·´²¡¶¾ = "{malware path and file name}"
Dropping Routine
This backdoor drops the following files:
- T
- %Common Startup%\Bf.exe
(Note: %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.)
Other Details
This backdoor connects to the following possibly malicious URL:
- {BLOCKED}4.110.6
- {BLOCKED}2.117.162
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
Restart in Safe Mode
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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- Avast·´²¡¶¾ = "{malware path and file name}"
Step 4
Search and delete these components
- T
- %Common Startup%\Bf.exe
Step 5
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_NITOL.UIQ. 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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