TROJ_DOFOIL.YUYIK

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

It does not have any propagation routine.

It does not have any backdoor routine.

It connects to certain websites to send and receive information. However, as of this writing, the said sites are inaccessible. It deletes the initially executed copy of itself.

Arrival Details

This Trojan 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 Trojan drops the following files:

• %User Temp%\emsjapan.png <- Executed afterwards

(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 drops and executes the following files:

• %User Temp%\2(1).exe - also detected as TROJ_DOFOIL.YUYIK

(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:

• %Application Data%\{random1}

(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:

• {Malware Generated Hash}

It injects codes into the following process(es):

• explorer.exe

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run
{installed program name in the system} = "%Application Data%\{random1}\{random2}.exe

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Dropping Routine

This Trojan drops the following files:

• %Application Data%\{random1}\{random2}.exe - copy of %User Temp%\2(1).exe

(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.)

Other Details

This Trojan connects to the following URL(s) to check for an Internet connection:

• http://www.msn.com

It connects to the following website to send and receive information:

• http://{BLOCKED}.{BLOCKED}.93.103

It does the following:

• It performs several checks before performing its malicious routine:
  • Flags of its PEB (IsDebugging, NtGlobalFlag) must not indicate that it is being debugged
  • Module filename must not contain the string “sample”
  • Volume serial number should not be 0xCD1A40 (ThreatExpert) or 0x70144646 (Malwr)
  • The modules dbghelp and sbiedll should not be loaded
  • Registry data under HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Disk\Enum must not contain qemu, virtual, vmware, xen, fffcce24 (VBox)
  • Registry subkey under HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall must not contain AutoItv3, CCleaner, WIC

However, as of this writing, the said sites are inaccessible.

It deletes the initially executed copy of itself

NOTES:

It connects to the URLs that are found in the following registry entries to trick the user and hide the true C&C from network sniffing tools:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall\{Installed Program} HelpLink = {url related to installed program}

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall\{Installed Program} URLInfoAbout = {url related to installed program}