BKDR_DLOAD.BH

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. It connects to a website to send and receive information.

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:

• %Application Data%\{random}.exe

(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 processes:

• svchost.exe

It injects codes into the following process(es):

• created svchost.exe

Backdoor Routine

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

• Sleep/Idle (2 minutes)
• Download and execute arbitrary file
• Update and uninstall itself
• Visit URL

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

• {BLOCKED}.{BLOCKED}.103.54:8080/{generated value}
• {BLOCKED}.{BLOCKED}.156.180:8080/{generated value}
• {BLOCKED}.{BLOCKED}.211.194:8080/{generated value}
• {BLOCKED}.{BLOCKED}.112.99:8080/{generated value}

Download Routine

This backdoor connects to the following website(s) to download and execute a malicious file:

• {BLOCKED}.{BLOCKED}.236.108:84/get/faa91cf5e79a76602f094ed38fad5872.exe - detected as TROJ_FAKESYS.BH, note that the URL may vary

NOTES:

If the malware failed to connect to any of the C&C servers, it creates the following registries:

HKEY_CURRENT_USER\SOFTWARE\{random}

HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
{random} = "%Application Data%\{random}.exe"

HKEY_CURRENT_USER\SOFTWARE\{random}
{random} = "{hex values}"

Note that the {generated value} is based on user name, user IP, running debugger, and malware build date and version.