WORM_PRONNY.IUY
Worm.Win32.Vobfus.eugf (Kaspersky); Win32/Pronny.LZ worm (Nod32)
Windows

Threat Type: Worm
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
This worm arrives by connecting affected removable drives to a system. 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 removable drives. These dropped copies use the names of the folders located on the said drives for their file names. It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system. As of this writing, the said sites are inaccessible.
It terminates itself if it detects it is being run in a virtual environment.
TECHNICAL DETAILS
Arrival Details
This worm arrives by connecting affected removable drives to a system.
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 worm drops the following non-malicious files:
- {removable drive letter}:\x.mpeg
It drops the following copies of itself into the affected system:
- %User Profile%\{random folder name}\{random file name}.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.)
It creates the following folders:
- %User Profile%\{random folder name}
(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 worm adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random file name} = {random file name} = "%User Profile%\{random folder name}\{random file name}.exe /{random character}"
It drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:
- {random file name}.lnk
Other System Modifications
This worm adds the following registry entries as part of its installation routine:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
UACDisableNotify = "0"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
EnableLUA = "0"
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows\WindowsUpdate\
AU
NoAutoUpdate = "1"
It modifies the following registry entries to hide files with Hidden attributes:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"
(Note: The default value data of the said registry entry is "1".)
Propagation
This worm drops the following copies of itself in all physical and removable drives:
- {removable drive letter}:\Love You.exe
- {removable drive letter}:\Money.exe
- {removable drive letter}:\Nude.exe
- {removable drive letter}:\Sex.exe
- {removable drive letter}:\{random file name}.exe
It drops copies of itself in removable drives. These dropped copies use the names of the folders located on the said drives for their file names.
It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
The said .INF file contains the following strings:
[autorun]
open={random file name}.exe
icon={random file name}.exe,0
or
{garbage characters}
[autorun]
{garbage characters}
open={random}.eXE
{garbage characters}
ACTION={random number}
UseautopLAY=1
{garbage characters}
Download Routine
This worm accesses the following websites to download files:
- {BLOCKED}1.{BLOCKED}k{random number}.com
- {BLOCKED}1.{BLOCKED}k{random number}.edu
- {BLOCKED}1.{BLOCKED}k{random number}.net
- {BLOCKED}1.{BLOCKED}k{random number}.org
It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.
As of this writing, the said sites are inaccessible.
Other Details
This worm terminates itself if it detects it is being run in a virtual environment.
It terminates itself if any of the following file(s) are present:
- sbiedll.dll (Sandboxie component)
- snxhk.dll (AVAST component)
NOTES:
It queries the HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Disk\Enum registry key for the following registry data strings to check if it is running in a virtual environment:
- *VIRTUAL*
- *VMWARE*
- *VBOX*
- *QEMU*
It will not continue its malicious routines when it found the following processes and module running in the system:
- VBoxService.exe
- vmtoolsd.exe
- SbieDll.dll
It drops the following shortcut files in removable drives:
- {removable drive letter}:\Favourites.lnk
- {removable drive letter}:\Movies.lnk
- {removable drive letter}:\Music.lnk
- {removable drive letter}:\Passwords.lnk
- {removable drive letter}:\Pictures.lnk
- {removable drive letter}:\Private.lnk
- {removable drive letter}:\Search.lnk
- {removable drive letter}:\Secret Folder.lnk
The shortcut files point to its dropped copy {removable drive letter}:\{random file name}.exe.
It also uses the names of existing folders and names of files with the following extensions for its dropped copies:
- .avi
- .bmp
- .doc
- .gif
- .jpe
- .jpg
- .mp3
- .mp4
- .mpg
- .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.
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
Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.
Step 3
Scan your computer with your Trend Micro product and note files detected as WORM_PRONNY.IUY
Step 4
Restart in Safe Mode
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- {random file name} = "%User Profile%\{random folder name}\{random file name}.exe /{random character}"
- {random file name} = "%User Profile%\{random folder name}\{random file name}.exe /{random character}"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
- UACDisableNotify = "0"
- UACDisableNotify = "0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system
- EnableLUA = "0"
- EnableLUA = "0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU
- NoAutoUpdate = "1"
- NoAutoUpdate = "1"
Step 6
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- From: ShowSuperHidden = "0"
To: ShowSuperHidden = "1"
- From: ShowSuperHidden = "0"
Step 7
Search and delete these folders
- %User Profile%\{random folder name}
Step 8
Search and delete these files
- %User Startup%\{random file name}.lnk
- {removable drive letter}:\Favourites.lnk
- {removable drive letter}:\Movies.lnk
- {removable drive letter}:\Music.lnk
- {removable drive letter}:\Passwords.lnk
- {removable drive letter}:\Pictures.lnk
- {removable drive letter}:\Private.lnk
- {removable drive letter}:\Search.lnk
- {removable drive letter}:\Secret Folder.lnk
- {removable drive letter}:\x.mpeg
Step 9
Search and delete AUTORUN.INF files created by WORM_PRONNY.IUY that contain these strings
- [autorun]
- open={random file name}.exe
- icon={random file name}.exe,0
- or
- {garbage characters}
- [autorun]
- {garbage characters}
- open={random}.eXE
- {garbage characters}
- ACTION={random number}
- UseautopLAY=1
- {garbage characters}
Step 10
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_PRONNY.IUY. 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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