F-Secure Lab just found a new, and it’s spreading in the wild. The worm is called Morto and it infects Windows workstations and servers. It uses a new spreading vector that we haven’t seen before: RDP (Remote Desktop Protocol). Windows has built-in support for this protocol via Windows
Once you enable a computer for remote use, you can use any other computer to access it.
When you connect to another computer with this tool, you can remotely use the computer, just like you’d use a local computer.
enabled. This creates a lot of traffic for port 3389/TCP, which is the RDP port.
When Morto finds a Remote Desktop server, it tries logging in as Administrator and tries a series of passwords:
Once you are connected to a remote system, you can access the drives of that server via Windows shares such as \\tsclient\c and \\tsclient\d for drives C: and D:, respectively. Morto uses this feature to copy itself to the target machine. It does this by creating a temporary drive under letter A: and copying a file called a.dll to it.