WORM_RETADUP.A

This information stealing malware was one of the IoCs found in recent attacks targeting hospitals in Israel. This malware is also notable for its stealth. It terminates itself after detecting anti-virus products, script file names, analysis, forensics, and debugging tools, as well as sandboxes and virtual machines.

This Worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes commands from a remote malicious user, effectively compromising the affected system.

It steals system information. It retrieves specific information from the affected system. It logs a user's keystrokes to steal information.

Arrival Details

This Worm 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 component file(s):

• C:\WinddowsUpdateCheck\WinddowsUpdater.zip

It drops the following copies of itself into the affected system:

• C:\WinddowsUpdateCheck\WinddowsUpdater.exe

It creates the following folders:

• C:\WinddowsUpdateCheck

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
WinddowsUpdater = "C:\WinddowsUpdater\WinddowsUpdater.exe C:\WinddowsUpdater\WinddowsUpdater.zip"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
WinddowsUpdate = "C:\WinddowsUpdater\WinddowsUpdater.exe C:\WinddowsUpdater\WinddowsUpdater.zip"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
WinddowsUpdater = "C:\WinddowsUpdater\WinddowsUpdater.exe C:\WinddowsUpdater\WinddowsUpdater.zip"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
WinddowsUpdate = "C:\WinddowsUpdater\WinddowsUpdater.exe C:\WinddowsUpdater\WinddowsUpdater.zip"

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

• %User Startup%\WinddowsUpdater.lnk

(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, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows XP, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

Other System Modifications

This Worm deletes the following files:

• %User Startup%\AntiWormUpdate.lnk
• %User Startup%\AntiUsbWormUpdate.lnk

(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, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows XP, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 0

Backdoor Routine

This Worm executes the following commands from a remote malicious user:

• Download files
• Connect to URLs
• Open a cmd to execute commands
• Install a keylogger
• Take a screenshot
• Extract password from browsers(Firefox, Opera, Chrome)
• Process start, terminate, restart

It connects to the following URL(s) to send and receive commands from a remote malicious user:

• http://{BLOCKED}stineop.com/myblog/user
• {BLOCKED}othere.publicvm.com
• {BLOCKED}016.linkpc.net
• {BLOCKED}016.publicvm.com
• {BLOCKED}al.publicvm.com
• {time-based hash}.linkpc.net
• {time-based hash}.ddns.net
• {time-based hash}.no-ip.info
• {time-based hash}.no-ip.biz
• {time-based hash}.zapto.org
• {time-based hash}.publicvm.com

Dropping Routine

This Worm drops the following file(s), which it uses for its keylogging routine:

• C:\WinddowsUpdateCheck\__.BIN

Information Theft

This Worm steals system information.

It retrieves the following information from the affected system:

• Information from browser (Chrome, Opera, Firefox)
• OS Version
• OS Architecture
• OS Service Pack
• Computer name
• Username
• Country Code
• Installed Antivirus product

It logs a user's keystrokes to steal information.

NOTES:

Anti-analysis Techniques

It checks the existence of AV products and analysis tools:

• avp.exe
• zonealarm.exe
• avguard.exe
• tcpview.exe
• procmon.exe
• nod32kui.exe
• kavmm.exe
• procmon.exe
• fsbwsys.exe
• vmacthlp.exe
• avp.exe
• Kavsvc.exe
• snxhk.dll
• tracer.dll
• SbieDll.dll
• api_log.dll
• dir_watch.dll
• dbghelp.dll
• monitornet.dll
• cuckoo
• SandCastle
• sandbox
• tracer.dll
• tracer.dll

• BehaviorDumper.exe
• FakeHTTPServer.exe
• FakeServer.exe
• FortiTracer.exe
• SbieSvc.exe
• VBoxService.exe
• VBoxTray.exe
• VMwareService.exe
• VMwareUser.exe
• guninraik.exe
• vmtoolsd.exe

Checks script filenames if containing the strings below, and must not have length greater than 35:

• "artifact"
• "sample"
• "."

Checks folder where it is being executed:

• "C:\virus"
• "C:\"

Checks if the following folders exist:

• "C:\CWSandbox\"
• "C:\Python26\"
• "C:\cuckoo\"

Checks Virtual Machines:

• "Bochs"
• "VirtualBox"
• "innotek"
• "VMware"

If any of the above are confirmed, the script will not continue.

Propagation

It drops copies of itself in all drives:

• {drive}\WinddowsUpdateCheck\WinddowsUpdater.exe
• {drive}\WinddowsUpdateCheck\WinddowsUpdater.zip

It drops the following shortcut files in all removable drives:

• {Drive}\My Pictures.lnk
• {Drive}\My Videos.lnk
• {Drive}\My Downloads.lnk

It also drops copies of itself inside the existing folders on removable drives

• {Drive}\{folder name}\Games.lnk
• {Drive}\{folder name}\Downloads.lnk
• {Drive}\{folder name}\{folder name}.lnk

Backdoor Commands

It is capable of the following commands:

• download_file ← download and execute files
• download_a3x ← download and execute autoit script
• msgbox ← display msgbox
• url ← visit url
• cmd ← execute command shell
• GoTorat ← execute RAT commands

If the backdoor command contains "GoTorat", it may perform the following commands:

• FILE_MANAGER_DOWNLOAD
• SCREEN_SHUT_INIT
• SCREEN_SHUT_STOP
• KEYLOGGER_INIT
• KEYLOGGER_STOP
• PASSWORD_INIT
• PASSWORD_STOP
• FILE_MANAGER_ROOT
• FILE_MANAGER_STOP
• SCREEN_THUMB
• MISC_INIT
• MISC_STOP
• RUN_SIMPLE_DISK
• RUN_SIMPLE_URL
• RUN_SCRIPT_DISK
• RUN_SCRIPT_URL

If the backdoor command contains "radbot", it may perform the following commands:

• GETINFO
• SLEEP
• EXIT
• RECONNECT
• MSGBOX
• URL
• CMD
• UPDATEE
• DOWNLOAD
• SHUTDOWN
• RESTART
• LOGOFF
• STANDBY

It checks for the presence of the following files:

• C:\WinddowsUpdateCheck\ebay.lnk
• C:\WinddowsUpdateCheck\hamazon.lnk
• C:\WinddowsUpdateCheck\hebay.lnk
• C:\WinddowsUpdateCheck\hmoneygram.lnk
• C:\WinddowsUpdateCheck\hpaypal.lnk
• C:\WinddowsUpdateCheck\hpayza.lnk
• C:\WinddowsUpdateCheck\hskrill.lnk
• C:\WinddowsUpdateCheck\hukash.lnk
• C:\WinddowsUpdateCheck\hwestern union.lnk
• C:\WinddowsUpdateCheck\moneygram.lnk
• C:\WinddowsUpdateCheck\paypal.lnk
• C:\WinddowsUpdateCheck\skrill.lnk
• C:\WinddowsUpdateCheck\ukash.lnk
• C:\WinddowsUpdateCheck\western union.lnk