TROJ_SMALL.SMJD
TrojanDownloader:Win32/Drstwex.A (Microsoft); Generic Dropper.ze (McAfee); Trojan.Gen (Symantec); Trojan-Downloader.Win32.Small.cdcm (Kaspersky); Trojan.Win32.Drwex.ab (v) (Sunbelt); Gen:Variant.Kazy.21497 (FSecure)
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
13,120 bytes
EXE
Yes
21 Jul 2012
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.
Autostart Technique
This Trojan registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\.ipsec
Other System Modifications
This Trojan deletes the following files:
- %System%\crt.dat
- %User Profile%\wevtapi.dll
- %User Profile%\taskmgr.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.. %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)
It adds the following registry keys:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
Notify\mdhcp32
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
Notify\dimsntfy32
HKEY_LOCAL_MACHINE\Software\Classes\
Interface\{5171463b-76a3-9033-2274-75c8f0a0edb6}
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
Notify\mdhcp32
DllName = "mdhcp32.dll"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
Notify\mdhcp32
Startup = "WinStart2EX"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
Notify\mdhcp32
Logoff = "WinOff2EX"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
Notify\mdhcp32
Shutdown = "WinOff2EX"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
Notify\mdhcp32
Asynchronous = "1"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
Notify\mdhcp32
Impersonate = "0"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
Notify\dimsntfy32
DllName = "dimsntfy32.dll"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
Notify\dimsntfy32
Startup = "WinStart"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
Notify\dimsntfy32
StartScreenSaver = "WinSS"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
Notify\dimsntfy32
StopScreenSaver = "WinSS"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
Notify\dimsntfy32
Asynchronous = "1"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
Notify\dimsntfy32
Impersonate = "0"
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{5171463b-76a3-9033-2274-75c8f0a0edb6}
u = "96"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\.ipsec
Type = "1"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\.ipsec
Start = "3"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\.ipsec
ImagePath = "\?"
Dropping Routine
This Trojan drops the following files:
- %User Temp%\_1.tmp
- %User Temp%\_2.tmp
- %User Temp%\_3.tmp
- sname
- %System%\shimg.dll
- %System%\dll.dll
- %System%\dimsntfy32.dll
- U
- L
- ACPI#PNP0303#2&da1a3ff&0\L\suianxvn
- ACPI#PNP0303#2&da1a3ff&0\@
(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.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)
This report is generated via an automated analysis system.
SOLUTION
9.200
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
Restart in Safe Mode
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
- .ipsec
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify
- mdhcp32
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify
- dimsntfy32
- In HKEY_LOCAL_MACHINE\Software\Classes\Interface
- {5171463b-76a3-9033-2274-75c8f0a0edb6}
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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\mdhcp32
- DllName = "mdhcp32.dll"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\mdhcp32
- Startup = "WinStart2EX"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\mdhcp32
- Logoff = "WinOff2EX"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\mdhcp32
- Shutdown = "WinOff2EX"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\mdhcp32
- Asynchronous = "1"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\mdhcp32
- Impersonate = "0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\dimsntfy32
- DllName = "dimsntfy32.dll"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\dimsntfy32
- Startup = "WinStart"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\dimsntfy32
- StartScreenSaver = "WinSS"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\dimsntfy32
- StopScreenSaver = "WinSS"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\dimsntfy32
- Asynchronous = "1"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\dimsntfy32
- Impersonate = "0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{5171463b-76a3-9033-2274-75c8f0a0edb6}
- u = "96"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\.ipsec
- Type = "1"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\.ipsec
- Start = "3"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\.ipsec
- ImagePath = "\?"
Step 5
Search and delete these files
- %User Temp%\_1.tmp
- %User Temp%\_2.tmp
- %User Temp%\_3.tmp
- sname
- %System%\shimg.dll
- %System%\dll.dll
- %System%\dimsntfy32.dll
- U
- L
- ACPI#PNP0303#2&da1a3ff&0\L\suianxvn
- ACPI#PNP0303#2&da1a3ff&0\@
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_SMALL.SMJD. 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 7
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%\crt.dat
- %User Profile%\wevtapi.dll
- %User Profile%\taskmgr.exe
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