terça-feira, 9 de junho de 2020

Linux Command Line Hackery Series - Part 5



Welcome back to the Linux Command Line Hackery series, this is Part-V of the series. Today we are going to learn how to monitor and control processes on our Linux box, so wrap your sleeves up and let's get started.

Command:    ps
Syntax:           ps [options]
Description:  ps displays information about the currently running processes. Some of the common flags of ps are described briefly below
Flags: 
  -A or -e -> select all processes
  -a -> select all processes except both session leaders and processes not associated with a terminal.
  T -> select all processes associated with current terminal
  -u <username or id> -> select all processes of a given user or userlist

Open up a terminal and type ps:

ps

what you'll see is a list of processes currently running in your terminal. One important thing to notice in the output is what's called as PID which stands for process ID. It is the number that uniquely identifies a process. Just keep that PID concept in mind we'll use it soon.

OK I know that's not really what you want to see rather you want to see all the processes that are currently running on your box. Don't worry we have flags to rescue, in order to see all the processes you can use the -e flag like this:

ps -e

Boom! you get a long list of processes currently running on your machine (don't stare at me like that, you asked and I gave you that). If you want to see processes of a particular user you can type the following command in your terminal:

ps -u bob

here "bob" is a username. This command will list all processes of the user with effective user name of bob.

You can do a full-format listing of the processes using the -f flag like this:

ps -fu bob

But the output of the ps command is a snapshot not really a live preview of what is going on in your box. I know your next question is going to be something like this, Isn't there a command in Linux that gives me a live updating information of the processes? Yes, there is a command called top that we'll learn about next.

Command:    top
Syntax:           top [options]
Description:  top gives a dynamic real-time view of a running system. That is, it gives the up-to-date information about all the processes running on your Linux box (sounds fun!). Besides giving information about current processes and threads top also provides a brief system summary.

To start top just type this command:

top

and you'll get a nice and cute looking ugly display :). Well what the heck is going on here you might ask, right? What you get is information about what is going on with your computer. To see what more can you do with top just type <h> within the program window and you'll be given list of options that you can play with.

OK looking at what processes are going on in your box is cool but what if you want to terminate (or close) a process, is there a command line utility for that? Yes, there is and that's what we are going to look at next.

Command:   kill
Syntax:          kill [options] <pid> [...]
Description:  kill is used to send a signal to process which by default is a TERM signal meaning kill by default sends a signal of termination to process (Cruel guy). To list the available signals we can use the -l or -L flag of the kill command.


To simply terminate a process we provide kill command a PID (process ID) and it will send the TERM signal to the process. So to kill a process first we'll list the running processes and then we'll keep the PID of the process in mind that we want to terminate. After that we'll issue the kill command with the PID that we just found.

ps -ax
kill 1153

the above command will send a TERM signal to the process whose PID is 1153, as simple as that.

We can also use our already learned skills to refine the output of ps command. Say we have a xterm terminal running on our box and we want to terminate it. By using ps command all alone we'll get a long listing of all processes running on our box. But we can limit the output of ps command to just those processes that we're interested in by piping ps command with the grep command like this:

ps -ax | grep xterm

wow! that's amazing, we're able to pull out only those results from the ps command that contained xterm in them. Isn't that a cool trick? But what is that vertical bar ( ) doing in the middle, you may be thinking, right? Remember we learned about the input and output re-directors previously, the vertical bar (pipe in geeky terms) is another re-director whose task is to redirect the output of one command as input to another command. Here the pipe redirects the output of ps -ax command as input to grep command and of-course from the previous article you know that grep is used to search for a PATTERN in the given input. That means the above command searches for the xterm word in the output of ps -ax command and then displays just those lines of ps -ax command which contain xterm. Now get that PID and kill that process.

That's it for today, try these commands up on your own box and remember practice is gonna make you master the Linux command line. :)

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System Hacking: Password Cracking Techniques And Types Of Passwords


This blog based on two major concepts:
  • Understand password-cracking techniques
  • Understand different types of passwords
  •  

The simplest way to crack the passwords

The first step is to access the system is that you should know how to crack the password of the target system. Passwords are the key element of information require to access the system, and users also selects passwords that are easy to guess such as mostly people has a passwords of their pet's name or room number etc to help them remember it. Because of this human factor, most password guessing is successful if some information is known about the target. Information gathering and reconnaissance can help give away information that will help a hacker guess a user's password.

Once a password is guessed or cracked, it can be the launching point for escalating privileges, executing applications, hiding files, and covering tracks. If guessing a password fails, then passwords may be cracked manually or with automated tools such as a dictionary or brute-force method.

Types of Passwords 

  • Only numbers
  • Only letters
  • Only special characters
  • Letters and numbers
  • Only letters and special characters 
  • Numbers, letters and special characters
A strong password is less susceptible to attack by a hacker. The following rules, proposed by the EC-Council, should be applied when you're creating a password, to protect it against attacks:
  • Must not contain any part of the user's account name
  • Must have a minimum of eight characters
  • Must contain characters from at least three of the following categories:
    • Non alphanumeric symbols ($,:"%@!#)
    • Numbers
    • Uppercase letters
    • Lowercase letters
A hacker may use different types of attacks in order to identify a password and gain further access to a system. The types of password attacks are as follows:

Passive Online

​Eavesdropping on network password exchanges. Passive online attacks
include sniffing, man-in-the-middle, and replay attacks. Moreover, a passive online attack is also known as sniffing the password on a wired or wireless network. A passive attack is not detectable to the end user. The password is captured during the authentication process and can then be compared against a dictionary file or word list. User account passwords are commonly hashed or encrypted when sent on the network to prevent unauthorized access and use. If the password is protected by encryption or hashing, special tools in the hacker's toolkit can be used to break the algorithm.

Another passive online attack is known as man-in-the-middle (MITM). In a MITM attack, the hacker intercepts the authentication request and forwards it to the server. By inserting a sniffer between the client and the server, the hacker is able to sniff both connections and capture passwords in the process.

A replay attack is also a passive online attack; it occurs when the hacker intercepts the password en route to the authentication server and then captures and resend the authentication packets for later authentication. In this manner, the hacker doesn't have to break the password or learn the password through MITM but rather captures the password and reuses the password-authentication packets later to authenticate as the client.

Active Online

Guessing the Administrator password. Active online attacks include auto-
mated password guessing. Moreover, The easiest way to gain administrator-level access to a system is to guess a simple password assuming the administrator used a simple password. Password guessing is an active online attack. It relies on the human factor involved in password creation and only works on weak
passwords.

Assuming that the NetBIOS TCP 139 port is open, the most effective method of breaking into a Windows NT or Windows 2000 system is password guessing. This is done by attempting to connect to an enumerated share ( IPC$ or C$ ) and trying a username and password combination. The most commonly used Administrator account and password combinations are words like Admin, Administrator, Sysadmin, or Password, or a null password.
A hacker may first try to connect to a default Admin$ , C$ , or C:\Windows share. To connect to the hidden C: drive share, for example, type the following command in the Run field (Start ➪ Run):

\\ip_address\c$

Automated programs can quickly generate dictionary files, word lists, or every possible combination of letters, numbers, and special characters and then attempt to log on using those credentials. Most systems prevent this type of attack by setting a maximum number of login attempts on a system before the account is locked.

In the following sections, we'll discuss how hackers can perform automated password guessing more closely, as well as countermeasures to such attacks.

Performing Automated Password Guessing

To speed up the guessing of a password, hackers use automated tools. An easy process for automating password guessing is to use the Windows shell commands based on the standard NET USE syntax. To create a simple automated password-guessing script, perform the following steps:
  1. Create a simple username and password file using Windows Notepad. Automated tools such as the Dictionary Generator are available to create this word list. Save the file on the C: drive as credentials.txt.
  2. Pipe this file using the FOR command: C:\> FOR /F "token=1, 2*" %i in (credentials.txt)
  3. Type net use \\targetIP\IPC$ %i /u: %j to use the credentials.txt file to attempt to log on to the target system's hidden share.

Offline Attacks

Offline attacks are performed from a location other than the actual computer where the passwords reside or were used. Offline attacks usually require physical access to the computer and copying the password file from the system onto removable media. The hacker then takes the file to another computer to perform the cracking. Several types of offline password attacks exist.

Types of AttackCharacteristicsPassword Example
Dictionary attackAttempts to use passwords from a list of dictionary wordsAdministrator
Hybrid attackSubstitutes numbers of symbols for password charactersAdm1n1strator
Brute-force attackTries all possible combinations of letters, numbers, and special charactersMs!tr245@F5a

A dictionary attack is the simplest and quickest type of attack. It's used to identify a password that is an actual word, which can be found in a dictionary. Most commonly, the attack uses a dictionary file of possible words, which is hashed using the same algorithm used by the authentication process. Then, the hashed dictionary words are compared with hashed passwords as the user logs on, or with passwords stored in a file on the server. The dictionary attack works only if the password is an actual dictionary word; therefore, this type of attack has some limitations. It can't be used against strong passwords containing numbers or other symbols.

A hybrid attack is the next level of attack a hacker attempts if the password can't be found using a dictionary attack. The hybrid attack starts with a dictionary file and substitutes numbers and symbols for characters in the password. For example, many users add the number 1 to the end of their password to meet strong password requirements. A hybrid attack is designed to find those types of anomalies in passwords.

The most time-consuming type of attack is a brute-force attack, which tries every possible combination of uppercase and lowercase letters, numbers, and symbols. A brute-force attack is the slowest of the three types of attacks because of the many possible combinations of characters in the password. However, brute force is effective; given enough time and processing power, all passwords can eventually be identified.

More info


Medusa: A Speedy, Parallel And Modular Login Brute-forcing Tool


About Medusa
   Medusa is a speedy, parallel, and modular, login brute-forcer. The goal is to support as many services which allow remote authentication as possible. The author considers following items as some of the key features of this application:

   Thread-based parallel testing. Brute-force testing can be performed against multiple hosts, users or passwords concurrently.

   Flexible user input. Target information (host/user/password) can be specified in a variety of ways. For example, each item can be either a single entry or a file containing multiple entries. Additionally, a combination file format allows the user to refine their target listing.

   Modular design. Each service module exists as an independent .mod file. This means that no modifications are necessary to the core application in order to extend the supported list of services for brute-forcing.

   Multiple protocols supported. Many services are currently supported (e.g. SMB, HTTP, MS-SQL, POP3, RDP, SSHv2, among others).

   See doc/medusa.html for Medusa documentation. For additional information:

Building on macOS

#getting the source
git clone https://github.com/jmk-foofus/medusa
cd medusa

#macOS dependencies
brew install freerdp
$ export FREERDP2_CFLAGS='-I/usr/local/include'
$ export FREERDP2_LIBS='-I/usr/local/lib/freerdp'

#building
./configure
make

#executing

./src/medusa
Medusa's Installation
   Medusa is already installed on Kali Linux, Parrot Security OS, BlackArch and any other Linux distros based for security pentesting purposes.

   For Debian-based distro users, open your Terminal and enter this command:
sudo apt install medusa

   For Arch Linux-based distro users, enter this command: sudo pacman -S medusa

About the author:

You might like these similar tools:
More information

Spyeye - Script To Generate Win32 .Exe File To Take Screenshots


Script to generate Win32 .exe file to take screenshots every ~10 seconds.

Features:
  • Works on WAN: Port Forwarding by Serveo.net
  • Fully Undetectable (FUD) -> Don't Upload to virustotal.com!

Legal disclaimer:
Usage of SpyEye for attacking targets without prior mutual consent is illegal. It's the end user's responsibility to obey all applicable local, state and federal laws. Developers assume no liability and are not responsible for any misuse or damage caused by this program

Usage:
git clone https://github.com/thelinuxchoice/spyeye
cd spyeye
bash install.sh
chmod +x spyeye
./spyeye

Author: github.com/thelinuxchoice
IG: instagram.com/linux_choice




via KitPloit

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