Backdoor.MSIL.REMCOS.TIOIBEGO

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.

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 drops the following copies of itself into the affected system:

• %Application Data%\splt\splt.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It drops the following files:

• %Application Data%\splt\splt.exe
• %ProgramData%\remcos\logs.dat
• %Temp%\AEI{4 random values}.tmp → deleted afterwards

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.. %Temp% is the Windows temporary folder, where it usually is C:\Windows\Temp on all Windows operating system versions.)

It adds the following processes:

• %Windows%\Microsoft.NET\Framework\v4.0.30319\csc.exe
• "cmd" /c mkdir "%Application Data%\splt"
• "cmd" /c schtasks /create /sc minute /mo 1 /tn "Nafifas" /tr "'%Application Data%\splt\splt.exe'" /f
• "cmd" /c copy "{Malware Path}\{Malware Filename}.exe" "%Application Data%\splt\splt.exe"

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It creates the following folders:

• %Application Data%\splt

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other System Modifications

This Backdoor adds the following registry keys as part of its installation routine:

HKEY_CURRENT_USER\Software\Rmc-FYTY80

It also creates the following registry entry(ies) as part of its installation routine:

HKEY_CURRENT_USER\Software\Rmc-FYTY80
exepath = {Hex Values}

HKEY_CURRENT_USER\Software\Rmc-FYTY80
licence = 664E563EC8C93F9B2417F07269DA1924

Other Details

This Backdoor connects to the following possibly malicious URL:

• {BLOCKED}.{BLOCKED}.{BLOCKED}.{BLOCKED}:9000 → using TCP

It adds the following scheduled tasks:

• Name: Nafifas
  Trigger: After triggered, repeat every 00:01:00 indefinitely
  Action: Start the program %Application Data%\splt\splt.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)