TROJ_RENOS.XBX
Windows 98, ME, NT, 2000, XP, Server 2003
Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.
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.
It adds certain registry entries to disable the Task Manager. This action prevents users from terminating the malware process, which can usually be done via the Task Manager.
It deletes itself after execution.
It displays fake alerts that warn users of infection. It also displays fake scanning results of the affected system. It then asks for users to purchase it once scanning is completed. If users decide to purchase the rogue product, users are directed to a certain website asking for sensitive information, such as credit card numbers.
TECHNICAL DETAILS
413,184 bytes
EXE
Yes
Downloads files
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:
- %User Temp%\AUTMGR32.EXE
- %User Temp%\topwesitjh
(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 displays the following fake error messages:
{1.bmp}
Other System Modifications
This Trojan adds the following registry keys:
HKEY_LOCAL_MACHINE\SOFTWARE\Defense Center
{default} =
It adds the following registry entries to disable the Task Manager:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
Disable TaskMgr = 1
Dropping Routine
This Trojan drops the following files:
- %User Temp%\mschrt20ex.dll
- %User Temp%\wscsvc32.exe
- asd{random number}.tmp.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.)
Other Details
This Trojan deletes itself after execution.
Rogue Antivirus Routine
This Trojan displays fake alerts that warn users of infection. It also displays fake scanning results of the affected system. It then asks for users to purchase it once scanning is completed. If users decide to purchase the rogue product, users are directed to a certain website asking for sensitive information, such as credit card numbers.
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
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\\policies\\system
- Disable TaskMgr=1
- Disable TaskMgr=1
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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.
- In HKEY_LOCAL_MACHINE\\SOFTWARE\\
- Defense Center
- Defense Center
Step 4
Search and delete these files
- %User Temp%\mschrt20ex.dll
- %User Temp%\wscsvc32.exe
- asd{random number}.tmp.exe
- %User Temp%\AUTMGR32.EXE
- %User Temp%\topwesitjh
Step 5
Scan your computer with your Trend Micro product to delete files detected as TROJ_RENOS.XBX. 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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