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virtualsocket

a nice library to interact with binaries (mainly developed for CTF exploits)

installation

git clone https://github.com/antoniobianchi333/virtualsocket.git
pip install -e virtualsocket/

usage

virtualsocket can be used transparently with binaries using either a TCP socket or stdout/stdin

using with TCP binaries

importing

from virtualsocket.virtualsocket import VirtualSocket
from virtualsocket.gsocket.netsocket import NetSocket

connecting

#suppose that your binary is listening on 127.0.0.1:7777
vs = VirtualSocket(NetSocket("127.0.0.1",7777))
vs.connect()

using with stdin/stderr binaries

importing

from virtualsocket.virtualsocket import VirtualSocket
from virtualsocket.gsocket.stdsocket import StdSocket

opening the binary

mkfifo /tmp/in
mkfifo /tmp/out
./my_std_binary < /tmp/out > /tmp/in

If you need to use GDB:

gdb ./my_std_binary
r < /tmp/out > /tmp/in

If programmed correctly, std binaries should flush the pipes correctly (by either calling flush or setting the buffering properly using setvbuf).

In case of problems, you can try:

unbuffer ./my_std_binary < /tmp/out > /tmp/in

or

stdbuf -i 0 -o 0 -e 0 ./my_std_binary < /tmp/out > /tmp/in

connecting

#suppose that your binary has been opened with: ./my_std_binary < /tmp/out > /tmp/in
vs = VirtualSocket(StdSocket("/tmp/in","/tmp/out"))
vs.connect()

communicating

Send and receive data

#send data
vs.send("datadatadata\n")

#receive 10 bytes
data = vs.recv(10)

#receive until the string "endofmessage"
data = vs.recv_until("endofmessage")

#receive until the word FLAG followed by three digits
data = vs.recv_until_regex(".*FLAG\d\d\d")

#receive everything for 2 seconds
data = vs.recv_time(2.0)

#receive "all":
#wait until we do not recv any new data for 0.2 seconds, blocking until "something" is received
data = vs.recv_all() #you should never use recv_all if you want reliable code!

Exceptions

#In case of communication problems (e.g., socket disconnected) or interrupted recv/send a CommunicationException is generated
from virtualsocket.virtualsocket import CommunicationException
try:
    vs.recv_time(10.0)
except CommunicationException, e:
    #we get here if the connection dies within 10 seconds
    #you can access data received before the exception
    data_received_so_far = e.data

Advanced features

#open interactive shell
vs.interact()

#get the entire communication history
vs.flow()

#CTRL+C
'''
At any time, while blocked in a recv, you can press CTRL+C.
Data received between the last recv and CTRL+C will be printed.
'''