Windows 2003/XP/2000/NT/ME/98/95

Bifrose.BLN is a backdoor that allows hackers to gain remote access to the affected computer in order to carry out actions that compromise user confidentiality and impede the tasks performed on the computer.

It captures certain information entered or saved by the user, with the corresponding threat to privacy: keystrokes, in order to obtain information for accessing online banking services, passwords and other confidential information.

It sends the gathered information to a remote user by any available means: email, FTP, etc.

It reduces the security level of the computer: it changes the security settings of Internet Explorer, decreasing its security level; it awaits remote-control orders received through IRC.

It uses stealth techniques to avoid being detected by the user:

• It uses techniques included in its code to hide itself while it is active.
• It injects itself in running processes.
• It deletes the original file from which it was run once it is installed on the computer.

Bifrose.BLN uses the following propagation or distribution methods:

• Exploiting vulnerabilities with the intervention of the user: exploiting vulnerabilities in file formats or applications. To exploit them successfully it needs the intervention of the user: opening files, viewing malicious web pages, reading emails, etc.
• Email: sending emails that include a copy of itself as an attachment. The computer is infected when the attachment is run.

Bifrose.BLN is easy to recognize, as it shows the following symptoms:

• It changes the homepage of Internet Explorer.