TROJ_OBFUSCA.HZB
PWS:Win32/Zbot.gen!B (Microsoft); Downloader-BON (McAfee); Suspicious.MLApp (Symantec); Trojan-Spy.Win32.Zbot.adko (Kaspersky); Packed.Win32.Katusha.c (v) (Sunbelt); Trojan horse Pakes_c.TT (AVG)
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This Trojan 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
231,424 bytes
EXE
Yes
07 May 2013
Arrival Details
This Trojan 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 Trojan drops the following copies of itself into the affected system:
- %System%\ntos.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
It creates the following folders:
- %System%\wsnpoem
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
userinit = "%System%\ntos.exe"
It modifies the following registry entries to ensure it automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
userinit = "%System%\userinit.exe,%System%\ntos.exe,"
(Note: The default value data of the said registry entry is %Windows%\system32\userinit.exe,.)
Other System Modifications
This Trojan deletes the following files:
- %System%\ntos.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Network
UID = "ANNA-CWS313_00164635"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer
{F710FA10-2031-3106-8872-93A2B5C5C620} = "{random values}"
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Network
UID = "ANNA-CWS313_00167DC0"
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Network
UID = "ANNA-CWS313_0016A9A2"
Dropping Routine
This Trojan drops the following files:
- %System%\wsnpoem\video.dll.cla
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
Other Details
This Trojan connects to the following possibly malicious URL:
- http://{BLOCKED}tral.cn/z/cfg.bin
This report is generated via an automated analysis system.
SOLUTION
9.300
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
Identify and delete files detected as TROJ_OBFUSCA.HZB using either the Startup Disk or Recovery Console
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- userinit = "%System%\ntos.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Network
- UID = "ANNA-CWS313_00164635"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer
- {F710FA10-2031-3106-8872-93A2B5C5C620} = "{random values}"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Network
- UID = "ANNA-CWS313_00167DC0"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Network
- UID = "ANNA-CWS313_0016A9A2"
Step 4
Restore these modified registry values
Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- From: userinit = "%System%\userinit.exe,%System%\ntos.exe,"
To: userinit = ""%Windows%\system32\userinit.exe,""
- From: userinit = "%System%\userinit.exe,%System%\ntos.exe,"
Step 5
Search and delete this file
- %System%\wsnpoem\video.dll.cla
Step 6
Search and delete this folder
- %System%\wsnpoem
Step 7
Scan your computer with your Trend Micro product to delete files detected as TROJ_OBFUSCA.HZB. 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.
Step 8
Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.
- %System%\ntos.exe
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