BKDR_ANDROM.JB

This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

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

It executes a remote command prompt. It deletes the initially executed copy of itself.

Arrival Details

This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

Installation

This backdoor drops the following copies of itself into the affected system:

• {All Users' profile}\svchost.exe
• {All Users' profile}\Local Settings\Temp\ms{random characters}.{extension name} (if running as administrator)
• %User Profile%\Local Settings\Temp\ms{random characters}.{extension name} (if not running as administrator)

(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.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
SunJavaUpdateSched = "{All Users' profile}\svchost.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
SunJavaUpdateSched = "{All Users' profile}\svchost.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
{volume serial number of drive C:} = "{All Users' profile}\Local Settings\Temp\ms{random characters}.{extension name}" (if running as administrator)

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
Load = "%User Profile%\Local Settings\Temp\ms{random characters}.{extension name}" (if not running as administrator)

Backdoor Routine

This backdoor opens the following ports:

• TCP port 8000

It executes the following commands from a remote malicious user:

• Download an .EXE file from a URL and save it as %User Temp%\{random number}.exe, then execute the file
• Download a file from a URL and save it in the following registry entries:
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft
    {file name} = "{contents of the file}" (if running as administrator)
  • HKEY_CURRENT_USER\Software\Microsoft
    {file name} = "{contents of the file}" (if not running as administrator)
• Save the contents of the following registry entries as %User Temp%\{random file name}.exe and execute the file:
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
    {random number} = "{contents of the file}" (if running as administrator)
  • HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
    {random number} = "{contents of the file}" (if not running as administrator)
• Download a .DLL file from the C&C server and save it as {All Users' profile}\ms{random characters}.{extension name}. Create the following registry entry:
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft
    {All Users' profile}\ms{random characters}.{extension name} = "{exported function of the downloaded .DLL file}" (if running as administrator)
  • HKEY_CURRENT_USER\Software\Microsoft
    {All Users' profile}\ms{random characters}.{extension name} = "{exported function of the downloaded .DLL file}" (if not running as administrator)
• Remove all malware entries in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft or HKEY_CURRENT_USER\Software\Microsoft and deletes the malware files they are pointing to
• Remove all malware entries in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft or HKEY_CURRENT_USER\Software\Microsoft and reexecute itself
• Uninstall self

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

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

• http://{BLOCKED}t.pl/image.php
• http://{BLOCKED}d.pl/image.php
• http://{BLOCKED}e.ru/image.php
• http://{BLOCKED}m.ru/image.php
• http://{BLOCKED}ve.com/image.php
• http://{BLOCKED}t.pl/image.php

Other Details

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

• www.update.microsoft.com:20480

It executes a remote command prompt.

It deletes the initially executed copy of itself

NOTES:

{extension name} is randomly chosen from any of the following:

• BAT
• CMD
• COM
• EXE
• PIF
• SCR

Upon execution, it executes the files pointed to by registry entries in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft if running as administrator, or HKEY_CURRENT_USER\Software\Microsoft if not running as administrator.