TROJ_DLOADER.AU
ARC:SIM, Trojan-Downloader.Win32.Delf.befh (Kaspersky); Trojan.Generic.6804412 (FSecure)
Windows 2000, Windows XP, Windows Server 2003
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
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 creates the following folders:
- %User Temp%\$inst
- %Program Files%\RealtekAudioDriver
(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.. %Program Files% is the default Program Files folder, usually C:\Program Files.)
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
Realtek Sound System Driver = "%Program Files%\RealtekAudioDriver\audiodrvx.exe"
Other System Modifications
This Trojan deletes the following files:
- %User Temp%\$inst\0.tmp
- %User Temp%\$inst\1.tmp
- %User Temp%\$inst\3.tmp
- %User Temp%\$inst\4.tmp
- %User Temp%\$inst\5.tmp
- %User Temp%\$inst\6.tmp
- %User Temp%\$inst\7.tmp
- %User Temp%\$inst\8.tmp
- %User Temp%\$inst\9.tmp
- %User Temp%\$inst\10.tmp
- %User Temp%\$inst\11.tmp
- %User Temp%\$inst\12.tmp
- %User Temp%\$inst\13.tmp
- %User Temp%\$inst\14.tmp
- %User Temp%\$inst\15.tmp
- %User Temp%\$inst\16.tmp
- %User Temp%\$inst\17.tmp
- %User Temp%\$inst\20.tmp
- %User Temp%\$inst\50.tmp
- %User Temp%\$inst\21.tmp
- %User Temp%\$inst\51.tmp
- %Program Files%\RealtekAudioDriver\setting.bat
(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.. %Program Files% is the default Program Files folder, usually C:\Program Files.)
It deletes the following folders:
- %User Temp%\$inst\
(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 adds the following registry keys:
HKEY_LOCAL_MACHINE\SOFTWARE\Pilla
HKEY_LOCAL_MACHINE\Software\ProTeko
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Pilla
BckName = "ralteksound.rmp"
HKEY_LOCAL_MACHINE\SOFTWARE\Pilla
Version = "1.1.1.0"
HKEY_LOCAL_MACHINE\SOFTWARE\Pilla
Name = "audiodrvx.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\ProTeko
Active = "karumango"
Dropping Routine
This Trojan drops the following files:
- %User Temp%\$inst\2.tmp
- %User Temp%\$inst\temp_0.tmp
- setting.bat
- %Windows%\ralteksound.rmp
(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.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)
Other Details
This Trojan connects to the following possibly malicious URL:
- https://{BLOCKED}y.com/bundles/asmin1/1
This report is generated via an automated analysis system.
SOLUTION
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\SOFTWARE
- Pilla
- In HKEY_LOCAL_MACHINE\Software
- ProTeko
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
- Realtek Sound System Driver = "%Program Files%\RealtekAudioDriver\audiodrvx.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Pilla
- BckName = "ralteksound.rmp"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Pilla
- Version = "1.1.1.0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Pilla
- Name = "audiodrvx.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\ProTeko
- Active = "karumango"
Step 5
Search and delete these folders
- %User Temp%\$inst
- %Program Files%\RealtekAudioDriver
Step 6
Search and delete these files
- %User Temp%\$inst\2.tmp
- %User Temp%\$inst\temp_0.tmp
- setting.bat
- %Windows%\ralteksound.rmp
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DLOADER.AU. 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.
- %User Temp%\$inst\0.tmp
- %User Temp%\$inst\1.tmp
- %User Temp%\$inst\3.tmp
- %User Temp%\$inst\4.tmp
- %User Temp%\$inst\5.tmp
- %User Temp%\$inst\6.tmp
- %User Temp%\$inst\7.tmp
- %User Temp%\$inst\8.tmp
- %User Temp%\$inst\9.tmp
- %User Temp%\$inst\10.tmp
- %User Temp%\$inst\11.tmp
- %User Temp%\$inst\12.tmp
- %User Temp%\$inst\13.tmp
- %User Temp%\$inst\14.tmp
- %User Temp%\$inst\15.tmp
- %User Temp%\$inst\16.tmp
- %User Temp%\$inst\17.tmp
- %User Temp%\$inst\20.tmp
- %User Temp%\$inst\50.tmp
- %User Temp%\$inst\21.tmp
- %User Temp%\$inst\51.tmp
- %Program Files%\RealtekAudioDriver\setting.bat
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