I'm having troubles getting this to work. Basically I have a python program that expect some data in stdin, that is reading it as sys.stdin.readlines() I have tested this and it is working without problems with things like echo "" | myprogram.py
I have a second program that using the subprocess module calls on the first program with the following code
proc = subprocess.Popen(final_shell_cmd,
stderr=subprocess.PIPE, stdout=subprocess.PIPE,
shell=False), env=shell_env)
f = ' '.join(shell_cmd_args)
#f.append('\4')
return proc.communicate(f)
The second program is a daemon and i have discovered that the second program works well as long as I hit ctrl-d after calling it from the first program.
So it seems there is something wrong with subprocess not closing the file and my first program expecting more input when nothing more should be sending.
anyone has any idea how I can get this working?
The main problem here is that "shell_cmd_args" may contain passwords and other sensitive information that we do not want to pass in as the command name as it will show in tools like "ps".
You want to redirect the subprocess's stdin, so you need stdin=subprocess.PIPE.
You should not need to write Control-D ('\4') to the file object. Control-D tells the shell to close the standard input that's connected to the program. The program doesn't see a Control-D character in that context.
Related
I currently try to do a Buffer Overflow attack to a simple C Program.
This Program takes 2 inputs via C's scanf function. The First input is secure, the second is not. So I found my shellcode, the padding and the new return adress. It should spawn a simple shell. So i tried it with the following:
#!/usr/bin/env python
...
p = subprocess.Popen(["/home/user/Desktop/A3/1/exploitme"], shell=True, stdout = subprocess.PIPE, stdin = subprocess.PIPE, stderr=subprocess.PIPE)
p.stdin.write('A\n')
p.stdin.write(OVERFLOWCODE)
stdout, stderr = p.communicate()
print(stdout)
But i don't see the //bin/sh terminal.
However I think the problem is not the Code i use (it should work fine), the Problem seems to be that like the command itself says that it just creates a subprocess where just the programm can communicate with, and not me.
So my question is, how can I make it possible to run the programm, enter two strings to the scanf's and then take control over the Program? Something like spawn a new Terminal and pipe the two commands in there.
The Problem is I can't just enter the Code manually because there is something like ASLR (it creates a buffer with size of srand of unix time in seconds), so I must calculate the return adress every second new.
Any Ideas to make this work?
I'm struggling to get some python script to start a subprocess, wait until it completes and then retrieve the required data. I'm quite new to Python.
The command I wish to run as a subprocess is
./bin.testing/Eva -t --suite="temp0"
Running that command by hand in the Linux terminal produces:
in terminal mode
Evaluation error = 16.7934
I want to run the command as a python sub-process, and receive the output back. However, everything I try seems to skip the second line (ultimately, it's the second line that I want.) At the moment, I have this:
def job(self,fen_file):
from subprocess import Popen, PIPE
from sys import exit
try:
eva=Popen('{0}/Eva -t --suite"{0}"'.format(self.exedir,fen_file),shell=True,stdout=PIPE,stderr=PIPE)
stdout,stderr=eva.communicate()
except:
print ('Error running test suite '+fen_file)
exit("Stopping")
print(stdout)
.
.
.
return 0
All this seems to produce is
in terminal mode
0
with the important line missing. The print statement is just so I can see what I am getting back from the sub-process -- the intention is that it will be replaced with code that processes the number from the second line and returns the output (here I'm just returning 0 just so I can get this particular bit to work first. The caller of this function prints the result, which is why there is a zero at the end of the output.) exedir is just the directory of the executable for the sub-process, and fen-file is just an ascii file that the sub-process needs. I have tried removing the 'in terminal mode' from the source code of the sub-process and re compiling it, but that doesn't work -- it still doesn't return the important second line.
Thanks in advance; I expect what I am doing wrong is really very simple.
Edit: I ought to add that the subprocess Eva can take a second or two to complete.
Since the 2nd line is an error message, it's probably stored in your stderr variable!
To know for sure you can print your stderr in your code, or you can run the program on the command line and see if the output is split into stdout and stderr. One easy way is to do ./bin.testing/Eva -t --suite="temp0" > /dev/null. Any messages you get are stderr since stdout is redirected to /dev/null.
Also, typically with Popen the shell=True option is discouraged unless really needed. Instead pass a list:
[os.path.join(self.exedir, 'Eva'), '-t', '--suite=' + fen_file], shell=False, ...
This can avoid problems down the line if one of your arguments would normally be interpreted by the shell. (Note, I removed the ""'s, because the shell would normally eat those for you!)
Try using subprocess check_output.
output_lines = subprocess.check_output(['./bin.testing/Eva', '-t', '--suite="temp0"'])
for line in output_lines.splitlines():
print(line)
I need to run a external exe file inside a python script. I need two things out of this.
Get whatever the exe outputs to the stdout (stderr).
exe stops executing only after I press the enter Key. I can't change this behavior. I need the script the pass the enter Key input after it gets the output from the previous step.
This is what I have done so far and I am not sure how to go after this.
import subprocess
first = subprocess.Popen(["myexe.exe"],shell=True,stdout=subprocess.PIPE)
from subprocess import Popen, PIPE, STDOUT
first = Popen(['myexe.exe'], stdout=PIPE, stderr=STDOUT, stdin=PIPE)
while first.poll() is None:
data = first.stdout.read()
if b'press enter to' in data:
first.stdin.write(b'\n')
first.stdin.close()
first.stdout.close()
This pipes stdin as well, do not forget to close your open file handles (stdin and stdout are also file handles in a sense).
Also avoid shell=True if at all possible, I use it a lot my self but best practices say you shouldn't.
I assumed python 3 here and stdin and stdout assumes bytes data as input and output.
first.poll() will poll for a exit code of your exe, if none is given it means it's still running.
Some other tips
one tedious thing to do can be to pass arguments to Popen, one neat thing to do is:
import shlex
Popen(shlex.split(cmd_str), shell=False)
It preserves space separated inputs with quotes around them, for instance python myscript.py debug "pass this parameter somewhere" would result in three parameters from sys.argv, ['myscript.py', 'debug', 'pass this parameter somewhere'] - might be useful in the future when working with Popen
Another thing that would be good is to check if there's output in stdout before reading from it, otherwise it might hang the application. To do this you could use select.
Or you could use pexpect which is often used with SSH since it lives in another user space than your application when it asks for input, you need to either fork your exe manually and read from that specific pid with os.read() or use pexpect.
I am running a sub-program using subprocess.popen. When I start my Python program from the command window (cmd.exe), the program writes some info and dates in the window as the program evolves.
When I run my Python code not in a command window, it opens a new command window for this sub-program's output, and I want to avoid that. When I used the following code, it doesn't show the cmd window, but it also doesn't print the status:
p = subprocess.Popen("c:/flow/flow.exe", shell=True, stdout=subprocess.PIPE)
print p.stdout.read()
How can I show the sub-program's output in my program's output as it occurs?
Use this:
cmd = subprocess.Popen(["c:/flow/flow.exe"], stdout=subprocess.PIPE)
for line in cmd.stdout:
print line.rstrip("\n")
cmd.wait() # you may already be handling this in your current code
Note that you will still have to wait for the sub-program to flush its stdout buffer (which is commonly buffered differently when not writing to a terminal window), so you may not see each line instantaneously as the sub-program prints it (this depends on various OS details and details of the sub-program).
Also notice how I've removed the shell=True and replaced the string argument with a list, which is generally recommended.
Looking for a recipe to process Popen data asynchronously I stumbled upon http://code.activestate.com/recipes/576759-subprocess-with-async-io-pipes-class/
This looks quite promising, however I got the impression that there might be some typos in it. Not tried it yet.
It is an old post, but a common problem with a hard to find solution. Try this: http://code.activestate.com/recipes/440554-module-to-allow-asynchronous-subprocess-use-on-win/
I'm using the OS.System command to call a python script.
example:
OS.System("call jython script.py")
In the script I'm calling, the following command is present:
x = raw_input("Waiting for input")
If I run script.py from the command line I can input data no problem, if I run it via the automated approach I get an EOFError. I've read in the past that this happens because the system expects a computer to be running it and therefore could never receive input data in this way.
So the question is how can I get python to wait for user input while being run in an automated way?
The problem is the way you run your child script. Since you use os.system() the script's input channel is closed immediately and the raw_input() prompt hits an EOF (end of file). And even if that didn't happen, you wouldn't have a way to actually send some input text to the child as I assume you'd want given that you are using raw_input().
You should use the subprocess module instead.
import subprocess
from subprocess import PIPE
p = subprocess.Popen(["jython", "script.py"], stdin=PIPE, stdout=PIPE)
print p.communicate("My input")
Your question is a bit unclear. What is the process calling your Python script and how is it being run? If the parent process has no standard input, the child won't have it either.