TROJ_DROPPR.SMH
Windows 2000, XP, Server 2003
Threat Type: Trojan
Destructiveness: Yes
Encrypted: No
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.
It also has rootkit capabilities, which enables it to hide its processes and files from the user.
It modifies the Internet Explorer Zone Settings.
TECHNICAL DETAILS
Varies
PE
Yes
12 Aug 2010
Hides files and processes
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 adds the following folders:
- %Windows%\efee3f32f
(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)
It drops the following copies of itself into the affected system:
- %Windows%\svchost32.exe
(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)
It injects codes into the following process(es):
- LSASS.EXE
- SVCHOST.EXE
Autostart Technique
This Trojan 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,%Windows%\{malware filename}.exe,
(Note: The default value data of the said registry entry is %System%\userinit.exe,.)
Other System Modifications
This Trojan adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Network
PID = {computer name}_{random numbers}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
EnableConcurrentSessions = 1
Rootkit Capabilities
This Trojan also has rootkit capabilities, which enables it to hide its processes and files from the user.
Web Browser Home Page and Search Page Modification
This Trojan modifies the Internet Explorer Zone Settings.
Dropping Routine
This Trojan drops the following files:
- %Windows%\efee3f32f\brrve.nls
- %Windows%\efee3f32f\wrfsf.nls
- %Windows%\host32.exe - also detected as TROJ_DROPPR.SMH
(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)
SOLUTION
8.900
7.382.05
15 Aug 2010
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
Scan your computer with your Trend Micro product and note files detected as TROJ_DROPPR.SMH
Step 3
Identify and delete files detected as TROJ_DROPPR.SMH using the Recovery Console
Step 4
Restore this modified 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 NT\CurrentVersion\Winlogon
- From: Userinit=%System%\userinit.exe,%Windows%\{malware filename}.exe,
To: %System%\userinit.exe,1
- From: Userinit=%System%\userinit.exe,%Windows%\{malware filename}.exe,
Step 5
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 NT\CurrentVersion\Network
- PID={computer name}_{random numbers}
- PID={computer name}_{random numbers}
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- EnableConcurrentSessions=1
- EnableConcurrentSessions=1
Step 6
Search and delete this folder
Step 7
Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPR.SMH. 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.
Did this description help? Tell us how we did.