Downloader.JTZ is a Trojan, which although seemingly inoffensive, can actually carry out attacks and intrusions.
It captures certain information entered or saved by the user, with the corresponding threat to privacy:
- In the local network:
it generates a large amount of network activity and consumes bandwidth.
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.
Downloader.JTZ accesses several websites to download files, which it then runs. These can be any type of file, although they are normally malware.
It uses stealth techniques to avoid being detected by the user:
- It injects itself in running processes.
- It deletes the original file from which it was run once it is installed on the computer.
- 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 a memory dump program is running, such as Procdump.
- Its code is encrypted and it is only decrypted when it is going to run. Because of this, its code is not legible through a memory dump.
- It terminates its own execution if it detects that a debugging program is active.
Downloader.JTZ 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.