TROJ_HPMYAPP.SM

This Trojan arrives via removable drives. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It drops copies of itself in all removable drives. It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

Arrival Details

This Trojan arrives via removable drives.

It 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 Profile%\{random}\{random}.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

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
{random} = %User Profile%\{random}\{random}.exe

It drops the following file(s) in the Windows Startup folder to enable its automatic execution at every system startup:

• %User Startup%\{random}.lnk - shortcut to dropped copy

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

Other System Modifications

This Trojan modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 1

(Note: The default value data of the said registry entry is 0.)

Propagation

This Trojan drops copies of itself in all removable drives.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

NOTES:

This is the Trend Micro detection for malware that uses a custom packer (or a “hacker” packer) to avoid detection. This sample belongs to the VOBFUS malware family that uses the custom packer. Note that this detection may also detect malware that belongs to other malware family (see TROJ_HPMYAPP)

Custom packer routines

It checks if the following file exists:

• c:\myapp.exe

It checks if it is executed on a virtual machine by searching for the following processes and terminates itself if found:

• vmtoolsd.exe
• VBoxService.exe

It checks if the executed copy of itself contains the following virtual machine module and terminates itself if found:

• SbieDll.dll (Sandboxie)

Once the custom packer completes the system check, it will decrypt and execute the embedded malware. As a result, the behavior of the embedded malware is exhibited on the affected system.

VOBFUS Routines

It checks if it is executed on a virtual machine by searching for the following strings and terminates itself if found:

• *VIRTUAL*
• *VMWARE*
• *VBOX*
• *QEMU*

It drops .LNK files in removable drives that point to a copy of itself. This is done to trick users into clicking the shorcut files and execute the malware copy. These .LNK files use the following file names:

• Love You.exe
• Nude.exe
• Sex.exe
• Money.exe
• Secret Folder.lnk
• Favourites.lnk
• Documents.lnk
• Private.lnk
• Passwords.lnk
• Movies.lnk
• Music.lnk
• Search.lnk
• Pictures.lnk

It also uses the names of existing folders and names of files with the following extensions:

• avi
• bmp
• doc
• gif
• jpe
• jpg
• mp3
• mp4
• mpg
• pdf
• png
• tif
• txt
• wav
• wma
• wmv
• xls

This routine enables the copy of the worm to execute first before opening the real folder or file. It then changes the attributes of the original folders and files to Hidden and System to avoid early detection.

It may attempts to connect to the following remote DNS server:

• nsi.{BLOCKED}imechk1.com
• nsi.{BLOCKED}imechk2.com
• nsi.{BLOCKED}imechk3.com
• nsi.{BLOCKED}imechk4.com
• nsi.{BLOCKED}imechk5.com
• nsi.{BLOCKED}imechk6.com
• nsi.{BLOCKED}imechk7.com
• nsi.{BLOCKED}imechk9.com
• nsi.{BLOCKED}imechk10.com
• nsi.{BLOCKED}imechk11.com
• nsi.{BLOCKED}imechk12.com
• nsi.{BLOCKED}imechk13.com
• nsi.{BLOCKED}imechk15.com
• nsi.{BLOCKED}imechk16.com
• nsi.{BLOCKED}imechk17.com
• nsi.{BLOCKED}imechk18.com
• nsi.{BLOCKED}imechk19.com
• nsi.{BLOCKED}imechk20.com
• nsi.{BLOCKED}imechk22.com
• nsi.{BLOCKED}imechk23.com
• nsi.{BLOCKED}imechk24.com
• nsi.{BLOCKED}imechk25.com
• nsi.{BLOCKED}imechk28.com
• nsi.{BLOCKED}imechk29.com