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

MSNWorm.ER is a worm that spreads by copying itself, without infecting other files.

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

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

• In the local network: it generates a large amount of network activity and consumes bandwidth.

It reduces the security level of the computer: it notifies the attacker that the computer has been compromised and is ready to be used maliciously; it awaits remote-control orders received through IRC; it changes system permissions, decreasing the security level.

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

• It injects itself in running processes.
• It modifies system permissions in order to hide itself.

MSNWorm.ER 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.
• Instant messaging: it sends links pointing to a copy of itself to all users included in the infected user's contacts list.