Analysis by: Augusto II Remillano

ALIASES:

Win32/Somoto.D (NOD32), Downloader.Win32.Somato.h (Kaspersky)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Potentially Unwanted Application

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Potentially Unwanted Application arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites. It may be manually installed by a user.

  TECHNICAL DETAILS

Tamaño del archivo 196,376 bytes
Tipo de archivo EXE
Residente en memoria Yes
Fecha de recepción de las muestras iniciales 06 Nov 2018

Arrival Details

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

It may be manually installed by a user.

Installation

This Potentially Unwanted Application drops the following files:

  • %User Temp%\nsw{random}.tmp\modern-header.bmp
  • %User Temp%\nsw{random}.tmp\modern-wizard.bmp
  • %User Temp%\nsw{random}.tmp\nsDialogs.dll
  • %User Temp%\nsw{random}.tmp\filesfrog-visible.rtf
  • %User Temp%\nsw{random}.tmp\System.dll
  • %AppDataLocal%\FilesFrog Update Checker\uninstall.exe
  • %Application Data%\Microsoft\Windows\Start Menu\Programs\FilesFrog Update Checker\Check for Updates.lnk
  • %Application Data%\Microsoft\Windows\Start Menu\Programs\FilesFrog Update Checker\Uninstall.lnk
  • %Desktop%\Check for Updates.lnk
  • %AppDataLocal%\FilesFrog Update Checker\update_checker.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, and 8.. %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista, 7, and 8.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.. %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Desktop on Windows Vista, 7, and 8.)

It creates the following folders:

  • %AppDataLocal%\FilesFrog Update Checker
  • %User Temp%\nsw{random}.tmp
  • %Application Data%\Microsoft\Windows\Start Menu\Programs\FilesFrog Update Checker

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista, 7, and 8.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, and 8.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

Autostart Technique

This Potentially Unwanted Application adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
SDP = "%AppDataLocal%\FilesFrog Update Checker\update_checker.exe /auto"

Other System Modifications

This Potentially Unwanted Application adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
FilesFrog Update Checker

HKEY_CURRENT_USER\Software\Somoto

HKEY_CURRENT_USER\Software\Somoto\
SDP

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
sdp

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
sdp\shell

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
sdp\shell\open

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
sdp\shell\open\
command

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\ProtocolExecute

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\ProtocolExecute\sdp

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
FilesFrog Update Checker
DisplayName = "FilesFrog Update Checker"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
FilesFrog Update Checker
DisplayIcon = "%AppDataLocal%\FilesFrog Update Checker\uninstall.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
FilesFrog Update Checker
UninstallString = "%AppDataLocal%\FilesFrog Update Checker\uninstall.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
FilesFrog Update Checker
NoModify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
FilesFrog Update Checker
NoRepair = "1"

HKEY_CURRENT_USER\Software\Somoto\
SDP
flags = "32"

HKEY_CURRENT_USER\Software\Somoto\
SDP
nc = "{hex value}"

HKEY_CURRENT_USER\Software\Somoto\
SDP
affid = "filesfrogvisible"

HKEY_CURRENT_USER\Software\Somoto\
SDP
muid = "{UID}"

HKEY_CURRENT_USER\Software\Somoto\
SDP
uid = "{UID}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
sdp
(Default) = "URL:SDP Protocol"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
sdp
URL Protocol = ""

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
sdp\shell\open\
command
(Default) = ""%AppDataLocal%\FilesFrog Update Checker\update_checker.exe"/protocol %1"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\ProtocolExecute\sdp
WarnOnOpen = "0"

HKEY_CURRENT_USER\Software\Somoto\
SDP
nc = "{hex value}"

HKEY_CURRENT_USER\Software\Somoto\
SDP
flags = "36"

Other Details

This Potentially Unwanted Application connects to the following possibly malicious URL:

  • http://{BLOCKED}k.{BLOCKED}date.com/get_list?uid={UID}&muid={UID}&user_interval=24&v=4.3.0&c=0&affid=filesfrogvisible&manual=1&t=0