BKDR_KULUOZ.WOY

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.

It executes commands from a remote malicious user, effectively compromising the affected system.

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:

• %AppDataLocal%\{random filename}.exe

(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 and 7.)

It adds the following processes:

• svchost.exe

It adds the following mutexes to ensure that only one of its copies runs at any one time:

• 2GVWNQJz1

It injects itself into the following processes as part of its memory residency routine:

• created svchost.exe

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random value 1} = "%AppDataLocal%\{random filename}.exe"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\{random key}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\{random key}
{random value 2} = "{hex values}"

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

• idl - sleep/idle
• run - download and execute file
• rem - uninstall malware from system
• rdl - update injected code in created svchost.exe and created registry entry
• red - update created registry entry
• upd - update copy of malware
• ear - update copy of malware and autorun registry entry

It connects to the following URL(s) to send and receive commands from a remote malicious user:

• http://{BLOCKED}.{BLOCKED}.122.67:443/{generated value}
• http://{BLOCKED}.{BLOCKED}.222.24:8080/{generated value}
• http://{BLOCKED}.{BLOCKED}.163.221:443/{generated value}
• http://{BLOCKED}.{BLOCKED}.50.228:443/{generated value}
• http://{BLOCKED}.{BLOCKED}.120.163:8080/generated value}
• http://{BLOCKED}.{BLOCKED}.17.8:8080/{generated value}

NOTES:

This malware checks if there is a running window with the following name:

• wireshark.exe
• Tfrmrpcap
• iptools.exe
• Iris - Version 5.59
• ProcessLasso_Notification_Class
• TSystemExplorerTrayForm.UnicodeClass
• PROCMON_WINDOW_CLASS
• PROCEXPL
• WdcWindow
• ProcessHacker
• 99929D61-1338-48B1-9433-D42A1D94F0D2-x64
• 99929D61-1338-48B1-9433-D42A1D94F0D2-x32
• 99929D61-1338-48B1-9433-D42A1D94F0D2
• Dumper
• Dumper64
• APISpy32Class
• VMwareDragDetWndClass
• VMwareSwitchUserControlClass
• vmtoolsd.exe
• prl_cc.exe
• prl_tools.exe
• SharedIntApp.exe
• VBoxTray.exe
• VBoxService.exe
• vmusrvc.exe
• vmsrvc.exe