BKDR_ANDROM.CL

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 connects to a website to send and receive information.

It does not have any information-stealing capability.

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:

• %ProgramData%\svchost.exe (Windows Vista and 7 only)
• {All User's Profile}\svchost.exe
• {All Users' Profile}\Local Settings\Temp\ms{random characters}.{extension name}

(Note: %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This is usually C:\ProgramData in Windows Vista and 7, or C:\Program Files on Windows 2000, XP (32-bit), and Server 2003, or C:\Program Files (x86) on Windows XP (64-bit).)

It adds the following processes:

• \system32\wuauclt.exe
• \syswow64\svchost.exe

It injects codes into the following process(es):

• \system32\wuauclt.exe
• \syswow64\svchost.exe

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 User's Profile}\svchost.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
{random digit} = "{All Users' Profile}\Local Settings\Temp\ms{random characters}.{extension name}"

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
{malware path}\{malware name}.exe = "{malware path}\{malware name}.exe:*:Enabled:{malware name}"

Backdoor Routine

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

• Download a file from C&C server and save it as %User Temp%\{random number}.exe
• Download a file from C&C server and save it in the folder %System Root%\Documents and Settings\All Users\ms{random number}.dat and loads it
• Start a process
• Uninstall itself
• Remote command prompt

(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.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

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

• http://{BLOCKED}oss.ru/image.php
• http://{BLOCKED}ipn.ru/image.php

Information Theft

This backdoor does not have any information-stealing capability.

Other Details

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

• www.update.microsoft.com

NOTES:

The {extension name} of the dropped copy is any of the following:

• bat
• cmd
• com
• exe
• pif
• scr

It checks if it is being run in a VMWare environment. If it is being run in a VMWare environment, it performs another routine where it will open Port 8000 and listen for a backdoor command for performing remote shell execution.

It does not have any information-stealing capability.