BKDR_RESCOMS.YYWL

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

It runs certain commands that it receives remotely from a malicious user. Doing this puts the affected computer and information found on the computer at greater risk.

It gathers certain information on the affected computer.

Arrival Details

This Backdoor 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 Backdoor creates the following folders:

• %Application Data%\Screens
• %Application Data%\remcos

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

• Remcos_Mutex_Inj
• remcos_jowruopvcmlbafo

Other System Modifications

This Backdoor adds the following registry entries:

HKEY_CURRENT_USER\Software\remcos_jowruopvcmlbafo
EXEpath = {Hex Values}

Backdoor Routine

This Backdoor executes the following command(s) from a remote malicious user:

• “ping”
• “getdrives” - Get Drive list
• “listfiles” - List all files
• “open” - Open a File
• “download” - Get file/s from Affected Computer
• “upload” - Upload file/s to Affected Computer
• “delete”- Delete File/s from Affected Computer
• “rename” - Rename File/s from Affected Computer
• “newfolder” - Create new Directory
• “search” - Search a file from affected computer
• “Stopsearch” - stop searching files from affected computer
• “downloadfromurltofile”
• “downloadfromlocaltofile”
• “getproclist”
• “prockill” - terminates process
• “getwindows” - list all open application
• “closewindow” - minimize
• “maxwindow” - maximize
• “restorewindow” - switch application
• “closeprocfromwindow” - Terminate application
• “execcom” - Run command
• “consolecmd” - open cmd
• “openaddress” - open webpage
• “initializescrcap” - opens screen capture
• “freescrcap” - close screen capture
• “initklfrm” - open keylogger
• “startonlinekl” - start live keylogger
• “stoponlinekl” - stop live keylogger
• “getofflinelogs” - download logs from %Application Data%\remcos\logs.dat
• “autogetofflinelogs” - set affected computer to send logs automatically
• “deletekeylog” - deletes %Application Data%\remcos\logs.dat
• “Clearlogins” - deletes cookies and stored browser logins
• “getscrslist” - get screenshots from %Application Data%\Screens\
• “dwldscr” - get screenshot
• “initcamcap” - start capturing image from camera if available
• “freecamcap” - ends capturing image
• “miccapture” - start capturing voice if mic is available
• “stopmiccapture” - ends capturing voice
• “pwgrab” - gets user password
• “Deletefile” - deletespecificfile
• “Close” - exits monitoring the affected computer
• “Uninstall” - remove startup registry entries and creates and execute
• a batch file in %User Temp%\ that will delete the host file
• “updatefromurl” - downloads file from internet, update registry entries creates and execute a batch file in %User Temp%\ that will replace all old files
• “updatefromlocal” - gets file from remote user update registry entries creates and execute a batch file in %User Temp%\ that will replace all old files
• “msgbox” - display a messagebox to affected computer
• “keyinput” - sends keyboard input
• “mclick” - sends mouse click
• “OSpower” - Shutdown affected Computer
• “getclipboard” - copy clipboard data
• “setclipboard” - set clipboard data
• “emptyclipboard”- clear clipboard data
• “dlldata” - sends dll to affected computer and loads it directly in the memory
• “dllurl” - downloads dll from url to affected computer and loads it directly in the memory
• “initfun” - do joke commands to affected computer
• “initremscript” - can create a VBS/JS/Bat script then execute to affected computer
• “initregedit” - can manipulate registry entries

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Dropping Routine

This Backdoor drops the following files:

• %Application Data%\Screens\{ascending number}.png -> Screenshots
• %Application Data%\remcos\logs.dat -> log file

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Information Theft

This Backdoor gathers the following information on the affected computer:

• User Name
• Computer Name
• IP address
• OS Version
• Keyboard strokes
• Computer Activity via Screenshots & Logs

Other Details

This Backdoor does the following:

• Makes the malware sleep if the following processes found running in the system:
  • Process Explorer
  • Process Monitor
• Checks presence of the following to see if its running in a virtual machine then terminates itself:
  • SbieDll.dll
  • VBOX
• This Backdoor appears to be a TESTING program