BKDR_XTOB.C

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:

• %System%\{random file name}.exe - for OS versions Windows XP and lower
• %Application Data%\Security Data\{random file name}.exe - for OS versions Windows 7 and Vista

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %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 and 7.)

It creates the following folders:

• %Application Data%\Security Data - for OS versions Windows 7 and Vista

(Note: %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 and 7.)

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

• system32

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 file name}.exe = "%System%\{random file name}.exe" - for OS versions Windows XP and lower

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random file name}.exe = "%Application Data%\Security Data\{random file name}.exe" - for OS versions Windows 7 and Vista

Other System Modifications

This backdoor creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
{random file name}.exe = "%System%\{random file name}.exe" - for OS versions Windows XP and lower

Backdoor Routine

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

• Backdoor Commands
• Perform SYN flood
• Peform DDOS
• Sleep
• Delete File
• Download and Execute File
• Open a connection using Socks5 Proxy

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

• http://{BLOCKED}d.to/reloadednet/ping.php
• http://{BLOCKED}d.to/reloadednet/sedo.php

Information Theft

This backdoor gathers the following data:

• User Name
• Host Name
• OS Version
• Product ID

Stolen Information

This backdoor sends the gathered information via HTTP POST to the following URL:

• http://{BLOCKED}d.to/reloadednet/sedo.php/id={Host Name}_{Product ID}&s5_uidx={digit}&os={OS Version}&s5=0&done

NOTES:

The dropped copy's file path and name may depend on the affected machine's OS version.

The file name and registry value name {random file name} can be any of the following:

• Windows
• Components
• Audio
• Storage
• Profile
• Data
• Resources
• Deamonu
• Loader
• Guard
• WinProtect
• WinShield
• WinGuard

This malware queries the following registry entry to get the product ID:

• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Product ID