BKDR_FYNLOSKI.SADR

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 and executes them:

• %User Profile%\My Documents\MSDCSC\msdcsc.exe
• %User Temp%\MC CRACKED.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.. %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.)

It drops the following component file(s):

• %User Temp%\e4jD.tmp_dir\exe4jlib.jar
• %User Temp%\e4jD.tmp_dir\i4jdel.exe
• %User Temp%\e4jD.tmp_dir\MinecraftSP.jar
• %User Temp%\e4jE.tmp_dir\exe4jlib.jar
• %User Temp%\e4jE.tmp_dir\i4jdel.exe
• %User Temp%\e4jE.tmp_dir\MinecraftSP.jar
• %User Temp%\e4jF.tmp_dir\exe4jlib.jar
• %User Temp%\e4jF.tmp_dir\i4jdel.exe;
• %User Temp%\e4jF.tmp_dir\MinecraftSP.jar
• %User Temp%\dclogs\{YYYY-MM-DD-S}.dc

(Note: %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.)

It creates the following folders:

• %User Profile%\My Documents\MSDCSC
• %User Temp%\e4jD.tmp_dir
• %User Temp%\e4jE.tmp_dir
• %User Temp%\e4jF.tmp_dir
• %User Temp%\dclogs\

(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.. %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.)

Autostart Technique

This backdoor creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKCU\Software\Microsoft\
Windows\CurrentVersion\Run
MicroUpdate = %User Profile%\My Documents\My Documents\MSDCSC\msdcsc.exe

HKLM\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
UserInit = %System%\userinit.exe,%User Profile%\My Documents\MSDCSC\msdcsc.exe

Other System Modifications

This backdoor adds the following registry keys:

HKCU\Software\DC3_FEXEC

Other Details

This backdoor connects to the following possibly malicious URL:

• {BLOCKED}.{BLOCKED}.155.100