TROJ_DROPPER.GAS
Trojan:Win32/Malagent (Microsoft), Trojan.Win32.Generic!BT (Sunbelt), BDS/Runner.as.2 (Antivir), BAT/Runner.AS!tr (Fortinet), Trojan.BAT.Runner (Ikarus), Win32/SecurityXploded.A (NOD32)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.
TECHNICAL DETAILS
Arrival Details
This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.
Installation
This Trojan adds the following folders:
- {All User's Profile}\Msn
- {All User's Profile}\Msn\Msn
- %System Root%\users\public\Public Document
- %ProgramData%\Msn
- %ProgramData%\Msn\Msn
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This is usually C:\ProgramData in Windows Vista and 7, or C:\Program Files on Windows 2000, XP (32-bit), and Server 2003, or C:\Program Files (x86) on Windows XP (64-bit).)
It drops the following files:
- %System Root%\users\public\Public Document\bmsn.klm
- %System Root%\users\public\Public Document\conf.reg
- %System Root%\users\public\Public Document\dmsn.klm
- %System Root%\users\public\Public Document\image viewer.exe
- %System Root%\users\public\Public Document\keeprun.ini
- %System Root%\users\public\Public Document\msn.lnk
- %System Root%\users\public\Public Document\msnw.exe
- %System Root%\users\public\Public Document\pic.bat
- %System Root%\users\public\Public Document\pic.gif
- %System Root%\users\public\Public Document\picture viewer.exe
- %System Root%\users\public\Public Document\picture.bat
- %System Root%\users\public\Public Document\SAM.bat
- %System Root%\users\public\Public Document\statu.bat
- %System Root%\users\public\Public Document\view.bat
- %System Root%\users\public\Public Document\viewer.bat
- {All User's Profile}\Msn\Msn\bmsn.klm
- {All User's Profile}\Msn\Msn\conf.reg
- {All User's Profile}\Msn\Msn\dmsn.klm
- {All User's Profile}\Msn\Msn\image viewer.exe
- {All User's Profile}\Msn\Msn\keeprun.ini
- {All User's Profile}\Msn\Msn\msn.lnk
- {All User's Profile}\Msn\Msn\msnw.exe
- {All User's Profile}\Msn\Msn\pic.bat
- {All User's Profile}\Msn\Msn\pic.gif
- {All User's Profile}\Msn\Msn\picture viewer.exe
- {All User's Profile}\Msn\Msn\picture.bat
- {All User's Profile}\Msn\Msn\PIC_{random charecters}_ _{random numbers} .jpeg
- {All User's Profile}\Msn\Msn\PIC_{random charecters}_ _{random numbers} .jpg
- {All User's Profile}\Msn\Msn\SAM.bat
- {All User's Profile}\Msn\Msn\statu.bat
- {All User's Profile}\Msn\Msn\view.bat
- {All User's Profile}\Msn\Msn\viewer.bat
- {All User's Profile}\Start Menu\Programs\Startup\msn.lnk
- %ProgramData%\Msn\Msn\bmsn.klm
- %ProgramData%\Msn\Msn\conf.reg
- %ProgramData%\Msn\Msn\dmsn.klm
- %ProgramData%\Msn\Msn\image viewer.exe
- %ProgramData%\Msn\Msn\keeprun.ini
- %ProgramData%\Msn\Msn\msn.lnk
- %ProgramData%\Msn\Msn\msnw.exe
- %ProgramData%\Msn\Msn\pic.bat
- %ProgramData%\Msn\Msn\pic.gif
- %ProgramData%\Msn\Msn\picture viewer.exe
- %ProgramData%\Msn\Msn\picture.bat
- %ProgramData%\Msn\Msn\PIC_{random charecters}_ _{random numbers} .jpeg
- %ProgramData%\Msn\Msn\PIC_{random charecters}_ _{random numbers} .jpg
- %ProgramData%\Msn\Msn\SAM.bat
- %ProgramData%\Msn\Msn\statu.bat
- %ProgramData%\Msn\Msn\view.bat
- %ProgramData%\Msn\Msn\viewer.bat
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This is usually C:\ProgramData in Windows Vista and 7, or C:\Program Files on Windows 2000, XP (32-bit), and Server 2003, or C:\Program Files (x86) on Windows XP (64-bit).)
Autostart Technique
This Trojan creates the following registry entries to enable automatic execution of dropped component at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
stat = "{All Users' Profile}\Msn\Msn\statu.bat"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
stat2 = "{All Users' Profile}\Msn\Msn\statu.bat"
Other System Modifications
This Trojan adds the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile
EnableFirewall = "0"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile
DoNotAllowExceptions = "0"
It modifies the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
EnableFirewall = "0"
(Note: The default value data of the said registry entry is 1.)
Other Details
This Trojan connects to the following possibly malicious URL:
- ftp.{BLOCKED}stia.com
SOLUTION
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
Restart in Safe Mode
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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- stat = "{All Users' Profile}\Msn\Msn\statu.bat"
- stat = "{All Users' Profile}\Msn\Msn\statu.bat"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- stat2 = "{All Users' Profile}\Msn\Msn\statu.bat"
- stat2 = "{All Users' Profile}\Msn\Msn\statu.bat"
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\DomainProfile
- EnableFirewall = "0"
- EnableFirewall = "0"
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\DomainProfile
- DoNotAllowExceptions = "0"
- DoNotAllowExceptions = "0"
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\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile
- From: EnableFirewall = "0"
To: EnableFirewall = "1"
- From: EnableFirewall = "0"
Step 5
Search and delete this folder
- %ProgramData%\Msn
- %System Root%\users\public\Public Document
- {All User's Profile}\Msn
Step 6
Search and delete these files
- {All User's Profile}\Start Menu\Programs\Startup\msn.lnk
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DROPPER.GAS. 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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