Maslan.B is a worm that monitors Internet Explorer windows, searching for text strings related to banking companies. If it finds any, Maslan.B logs the keystrokes entered by the user and sends them to a certain website. This could reveal confidential information, such as credit card number, PIN, passwords, etc.
Maslan.B overwrites any files with a ZIP, RAR, PIF or EXE extension that contain certain text strings in their file name. Maslan.B replaces them with a copy of itself, and adds as many zeros as necessary, so that they maintain their original size.
Maslan.B spreads via e-mail, in a message with variable characteristics. It also spreads by attacking remote computers, in which it exploits the LSASS vulnerability, critical for Windows XP/2000 operating systems that are not properly updated.
If you have a Windows XP/2000 computer, it is highly recommendable to download the security patch for the LSASS vulnerability from the Microsoft website.