TROJ_FAKEMS.CA

This malware is involved with a spam attack during January 2013. It arrives as a dropped file from a spammed mail with the body written in the Japanese language and bearing the subject New Year Greetings. It appends garbage code to the copy it drops in order to avoid detection.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

This Trojan may be dropped by other malware.

It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system. As of this writing, the said sites are inaccessible.

It deletes the initially executed copy of itself.

Arrival Details

This Trojan may be dropped by the following malware:

• TROJ_DROPPER.AJM

Installation

This Trojan drops the following copies of itself into the affected system and executes them:

• %Program Files%\Windows NT\Accessories\Microsoft\mslives.exe

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

Autostart Technique

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

HKLM\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
msliveupdate = "%Program Files%\Windows NT\Accessories\Microsoft\mslives.exe"

Download Routine

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

• http://www.{BLOCKED}a-group.co.jp/news/topics.html

It saves the files it downloads using the following names:

• %User Temp%\mscxml.exe

(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 then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

As of this writing, the said sites are inaccessible.

Other Details

This Trojan deletes the initially executed copy of itself

NOTES:

This Trojan checks if the full path of the current running process is %Program Files%\Windows NT\Accessories\Microsoft\mslives.exe. If so, it will download a file. But if the full path is different, it will drop a copy of itself, %Program Files%\Windows NT\Accessories\Microsoft\mslives.exe, and execute it afterwards.

Also, it drops copies of itself in various file size, appending garbage codes, to avoid easy detection.