TROJ_SHARIK.YUYKD

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 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 copies of itself into the affected system:

• %Application Data%\{random1}\{random2}.exe
• %User Temp%\{random1}\{random2}.exe

(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.)

It adds the following processes:

• svchost.exe

It creates the following folders with attributes set to System and Hidden to prevent users from discovering and removing its components:

• %Application Data%\{random1}
• %User Temp%\{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.. %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 adds the following mutexes to ensure that only one of its copies runs at any one time:

• hashed computer name and volume serial number

It injects codes into the following process(es):

• explorer.exe
• created svchost.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

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

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{installed program name in the system} = "%User Temp%\{random1}\{random2}.exe

It drops the following shortcut pointing to its copy in the User Startup folder to enable its automatic execution at every system startup:

• %User Startup%\{random1}.lnk

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Other Details

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

• http://www.msn.com

It does the following:

• It performs several checks before performing its malicious routines:
  • The following flags of its PEB structure must not indicate that it is being debugged:
    • IsDebugging
    • NtGlobalFlag
  • Module filename must not contain the string “sample
  • Registry subkey under HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall must not contain the following strings (possible fingerprint for Joe Sandbox):
    • AutoItv3
    • CCleaner
    • WIC
  • Volume serial number should not be:
    • 0xCD1A40 (ThreatExpert)
    • 0x70144646 (Malwr)
  • Registry data under HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Disk\Enum must not contain the following strings:
    • qemu
    • virtual
    • vmware
    • xen
  • The following modules should not be loaded:
    • dbghelp
    • sbiedll

It deletes the initially executed copy of itself

NOTES:

The installed path is either %Application Data%\{random1}\ or %User Temp%\{random1}\

The strings {random1} and {random2} are generated from hashed computer name.

Both {random1} and {random2} are generated from hashed computer name.

It only creates one autostart registry entry.

It creates a thread that monitors its autostart registy.

It looks for the window name Shell_TrayWnd and then opens the process associated with the said window to execute its code. The commonly associated process from Shell_TrayWnd is explorer.exe. It does this routine to inject its code to explorer.exe, if the injection fails, it then inject its code on svchost.exe instead.

It connects to certain websites to send and receive information:

• http://{BLOCKED}.{BLOCKED}.175.138/81pRaeqJ0XF

It sends the following HTTP request to report status of infection:

cmd={getload or grab or getproxy}
login={hashed computer name and volume serial number}
bits={value}
file={value}
run=ok
run=fail
sel={malware version/name}
ver={os version}
doubles=1
personal=ok
removed=ok
admin={value}
hash={value}

However, the aforementioned URL and HTTP request are inaccessible.

It connects to certain URLs that are found in the following registry entries to trick users 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}

It does not have rootkit capabilities.

It does not exploit any vulnerability.