BKDR_ANDROM.B

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 deletes the initially executed copy of itself.

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:

• {All User's Profile}\Local Settings\Temp\ms{random characters}.{extension name}
• {All User's Profile}\svchost.exe

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

• {Decimal form of the Volume Serial Number of %System Root%}

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

It injects codes into the following process(es):

• wuauclt.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 number} = "{All User's Profile}\Local Settings\Temp\ms{random characters}.{extension 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 {All User's Profile}\ms{random number}.dat and loads it
• Start a process
• Uninstall itself

(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.)

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

• http://{BLOCKED}e.com/image.php - blocked
• http://{BLOCKED}ep.ru/image.php - blocked
• http://{BLOCKED}oes.com/image.php - blocked
• http://{BLOCKED}m.ru/image.php - blocked
• http://{BLOCKED}s.com/image.php - blocked
• http://{BLOCKED}ge.com/image.php - blocked

Other Details

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

• http://www.update.microsoft.com

It deletes the initially executed copy of itself

NOTES:
Where {extension name} is any of the following:

• BAT
• CMD
• COM
• EXE
• PIF
• SCR