Replacer.B 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:
It sends the gathered information to a remote user by any available means: email, FTP, etc.
It affects productivity, preventing tasks from being carried out:
- In the affected computer:
it converts the computer into a platform for taking malicious action surreptitiously: spam sending, launch of Denial of Service attacks, malware distribution, etc.
It reduces the security level of the computer:
it changes the security settings of Internet Explorer, decreasing its security level; it changes system permissions, decreasing the security level.
It uses stealth techniques to avoid being detected by the user:
- It modifies system permissions in order to hide itself.
It uses several methods in order to avoid detection by antivirus companies:
- It terminates its own execution if it detects that it is being executed in a virtual machine environment, such as VMWare or VirtualPC.
- It prevents scanning tools from running, such as Windows Registry Editor, FileMonitor, etc.
- It terminates its own execution if it detects that a memory dump program is running, such as Procdump.
- It terminates its own execution if it detects that a debugging program is active.
Replacer.B 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.
- Peer-to-peer (P2P) file sharing programs: it makes copies of itself with enticing names in shared folders belonging to these programs. Other users of this type of networks then voluntarily download and run the infected files.