BKDR_NIOUPALE.E
Backdoor:Win32/Nioupale.A (Microsoft); Trojan.Win32.Staser.tdh (Kaspersky); Gen:Trojan.Heur.PT.emW@bSkfiSp (BitDefender); Backdoor.Daserf.B (Norton)
Windows
![](/vinfo/imgFiles/legend.jpg)
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.
It deletes itself after execution.
TECHNICAL DETAILS
77,824 bytes
EXE
Yes
27 May 2015
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 and executes them:
- %User Profile%\System\Library\mshost.exe (for Windows Vista and above)
- %Program Files%\Common Files\System\Library\mshost.exe (for Windows XP and below)
(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.. %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 drops the following files:
- %User Profile%\System\Library\msid.dat (for Windows Vista and above)
- %Program Files%\Common Files\System\Library\msid.dat (for Windows XP and below)
(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.. %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.)
Autostart Technique
This backdoor registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\xnbmwess
ImagePath = "%Program Files%\Common Files\System\Library\mshost.exe" (for Windows XP and below)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\xnbmwess
Start = "2" (for Windows XP and below)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\xnbmwess
DisplayName = "Microsoft Windows Smart Storage Service" (for Windows XP and below)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\xnbmwess\Security
Security = "{hex value}" (for Windows XP and below)
It adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xnbmwess = "%User Profile%\System\Library\mshost.exe" (for Windows Vista and above)
Other System Modifications
This backdoor adds the following registry keys:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\xnbmwess (for Windows XP and below)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\xnbmwess\Security (for Windows XP and below)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\xnbmwess\Enum (for Windows XP and below)
Other Details
This backdoor connects to the following possibly malicious URL:
- http://sit.{BLOCKED}climb.com/main/image/adfu.gif
It deletes itself after execution.
SOLUTION
9.750
11.696.03
27 May 2015
11.697.00
28 May 2015
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
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
- xnbmwess (for Windows XP and below)
- xnbmwess (for Windows XP and below)
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\CurrentVersion\Run
- xnbmwess = "%User Profile%\System\Library\mshost.exe" (for Windows Vista and above)
- xnbmwess = "%User Profile%\System\Library\mshost.exe" (for Windows Vista and above)
Step 5
Search and delete these files
- %Program Files%\Common Files\System\Library\msid.dat (for Windows XP and below)
- %User Profile%\System\Library\msid.dat (for Windows Vista and above)
Step 6
Scan your computer with your Trend Micro product to delete files detected as BKDR_NIOUPALE.E. 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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