Asimov.1539 is a virus that spreads to other computers by copying its code to other files or programs.

Asimov.1539 prevents access from programs to websites of several companies related with security tools (antivirus programs, firewalls, etc.).

Asimov.1539 redirects attempts to access web pages of certain banks to spoofed pages, with the aim of logging information entered by the user in these pages.

Asimov.1539 redirects attempts to access several web pages to a specific IP address.

Asimov.1539 does not spread automatically using its own means. It needs an attacking user's intervention in order to reach the affected computer. The means of transmission used include, among others, floppy disks, CD-ROMs, email messages with attached files, Internet downloads, FTP, IRC channels, peer-to-peer (P2P) file sharing networks, etc.

Asimov.1539 uses the following infection strategies:

• Resident: once it has been run, the virus goes memory resident and stops functions belonging to the operating system. Therefore, every time the operating system or an application tries to access any of these functions, the virus will activate and infect new files.
• Companion: it renames files on the infected computer. This virus also makes copies of itself, and assigns them the original names of the files it has renamed. When users try to open the original file, they will actually be running a copy of the virus.
• Polymorphic: it encrypts itself in a different way with each infection it carries out. In order to do this, it uses different keys and operations. As a result, the virus has different characteristics in each new infection, which makes it difficult for antivirus pro-grams to detect this virus.