SUPREMA SEGURANÇA

SIL

Welcome back to Linux Command Line Hackery series, I hope you've enjoyed this series so far and would have learned something (at least a bit). Today we're going to get into user management, that is we are going to learn commands that will help us add and remove users and groups. So bring it on...

Before we get into adding new users to our system lets first talk about a command that will be useful if you are a non-root user.

Command: sudo
Syntax: sudo [options] command
Description: sudo allows a permitted user to execute a command as a superuser or another user.

Since the commands to follow need root privileges, if you are not root then don't forget to prefix these commands with sudo command. And yes you'll need to enter the root password in order to execute any command with sudo as root.

Command: useradd
Syntax: useradd [options] username
Description: this command is used for creating new user but is kinda old school.
Lets try to add a new user to our box.
[Note: I'm performing these commands as root user, you'll need root privileges to add a new user to your box. If you aren't root then you can try these commands by prefixing the sudo command at the very beginning of these command like this sudo useradd joe. You'll be prompted for your root password, enter it and you're good to go]

useradd joe

To verify that this command has really added a user to our box we can look at three files that store a users data on a Linux box, which are:

/etc/passwd -> this file stores information about a user separated by colons in this manner, first is login name, then in past there used to be an encrypted password hash at the second place however since the password hashes were moved to shadow file now it has a cross (x) there, then there is user id, after it is the user's group id, following it is a comment field, then the next field contains users home directory, and at last is the login shell of the user.

/etc/group -> this file stores information about groups, that is id of the group and to which group an user belongs.

/etc/shadow -> this file stores the encrypted password of users.

Using our command line techniques we learned so far lets check out these files and verify if our user has been created:

cat /etc/passwd /etc/group /etc/shadow | grep joe

In the above screenshot you can notice an ! in the /etc/shadow, this means the password of this user has not been set yet. That means we have to set the password of user joe manually, lets do just that.

Command: passwd
Syntax: passwd [options] [username]
Description: this command is used to change the password of user accounts.
Note that this command needs root privileges. So if you are not root then prefix this command with sudo.

passwd joe

After typing this command, you'll be prompted password and then for verifying your password. The password won't show up on the terminal.
Now joe's account is up and running with a password.

The useradd command is a old school command, lets create a new user with a different command which is kinda interactive.

Command: adduser
Syntax: adduser [options] user
Description: adduser command adds a user to the system. It is more friendly front-end to the useradd command.

So lets create a new user with adduser.

adduser jane

as seen in the image it prompts for password, full name and many other things and thus is easy to use.

OK now we know how to create a user its time to create a group which is very easy.

Command: addgroup
Syntax: addgroup [options] groupname
Description: This command is used to create a new group or add an existing user to an existing group.

We create a new group like this

addgroup grownups

So now we have a group called grownups, you can verify it by looking at /etc/group file.
Since joe is not a grownup user yet but jane is we'll add jane to grownups group like this:

addgroup jane grownups

Now jane is the member of grownups.

Its time to learn how to remove a user from our system and how to remove a group from the system, lets get straight to that.

Command: deluser
Syntax: deluser [options] username
Description: remove a user from system.

Lets remove joe from our system

deluser joe

Yes its as easy as that. But remember by default deluser will remove the user without removing the home directory or any other files owned by the user. Removing the home directory can be achieved by using the --remove-home option.

deluser jane --remove-home

Also the --remove-all-files option removes all the files from the system owned by the user (better watch-out). And to create a backup of all the files before deleting use the --backup option.

We don't need grownups group so lets remove it.

Command: delgroup
Syntax: delgroup [options] groupname
Description: remove a group from the system.

To remove grownups group just type:

delgroup grownups

That's it for today hope you got something in your head.

More info

SIL

Are you tired of reading endless news stories about ethical hacking and not really knowing what that means? Let's change that!

This Post is for the people that:

Have No Experience With Cybersecurity (Ethical Hacking)
Have Limited Experience.
Those That Just Can't Get A Break

OK, let's dive into the post and suggest some ways that you can get ahead in Cybersecurity.

I receive many messages on how to become a hacker. "I'm a beginner in hacking, how should I start?" or "I want to be able to hack my friend's Facebook account" are some of the more frequent queries. Hacking is a skill. And you must remember that if you want to learn hacking solely for the fun of hacking into your friend's Facebook account or email, things will not work out for you. You should decide to learn hacking because of your fascination for technology and your desire to be an expert in computer systems. Its time to change the color of your hat 😀

I've had my good share of Hats. Black, white or sometimes a blackish shade of grey. The darker it gets, the more fun you have.

If you have no experience don't worry. We ALL had to start somewhere, and we ALL needed help to get where we are today. No one is an island and no one is born with all the necessary skills. Period.OK, so you have zero experience and limited skills…my advice in this instance is that you teach yourself some absolute fundamentals.

Let's get this party started.

What is hacking?

Hacking is identifying weakness and vulnerabilities of some system and gaining access with it.

Hacker gets unauthorized access by targeting system while ethical hacker have an official permission in a lawful and legitimate manner to assess the security posture of a target system(s)

There's some types of hackers, a bit of "terminology".
White hat — ethical hacker.
Black hat — classical hacker, get unauthorized access.
Grey hat — person who gets unauthorized access but reveals the weaknesses to the company.
Script kiddie — person with no technical skills just used pre-made tools.
Hacktivist — person who hacks for some idea and leaves some messages. For example strike against copyright.

Skills required to become ethical hacker.

Curosity anf exploration
Operating System
Fundamentals of Networking

*Note this sites

More info

SIL

An HTTP Request Smuggling / Desync testing tool written in Python 3

IMPORTANT

This tool does not guarantee no false-positives or false-negatives. Just because a mutation may report OK does not mean there isn't a desync issue, but more importantly just because the tool indicates a potential desync issue does not mean there definitely exists one. The script may encounter request processors from large entities (i.e. Google/AWS/Yahoo/Akamai/etc..) that may show false positive results.

Installation

git clone https://github.com/defparam/smuggler.git
cd smuggler
python3 smuggler.py -h

Example Usage

Single Host:

python3 smuggler.py -u <URL>

List of hosts:

cat list_of_hosts.txt | python3 smuggler.py

Options

usage: smuggler.py [-h] [-u URL] [-v VHOST] [-x] [-m METHOD] [-l LOG] [-q]
                   [-t TIMEOUT] [--no-color] [-c CONFIGFILE]

optional arguments:
  -h, --help            show this help message and exit
  -u URL, --url URL     Target URL with Endpoint
  -v VHOST, --vhost VHOST
                        Specify a virtual host
  -x, --exit_early      Exit scan on first finding
  -m METHOD, --method METHOD
                        HTTP method to use (e.g GET, POST) Default: POST
  -l LOG, --log LOG     Specify a log file
  -q, --quiet           Quiet mode will only log issues found
  -t TIMEOUT, --timeout TIMEOUT
                        Socket timeout value Default: 5
  --no-color            Suppress color codes
  -c CONFIGFILE, --configfile CONFIGFILE
                        Filepath to the configuration file of payloads

Smuggler at a minimum requires either a URL via the -u/--url argument or a list of URLs piped into the script via stdin. If the URL specifies https:// then Smuggler will connect to the host:port using SSL/TLS. If the URL specifies http:// then no SSL/TLS will be used at all. If only the host is specified, then the script will default to https://

Use -v/--vhost <host> to specify a different host header from the server address

Use -x/--exit_early to exit the scan of a given server when a potential issue is found. In piped mode smuggler will just continue to the next host on the list

Use -m/--method <method> to specify a different HTTP verb from POST (i.e GET/PUT/PATCH/OPTIONS/CONNECT/TRACE/DELETE/HEAD/etc...)

Use -l/--log <file> to write output to file as well as stdout

Use -q/--quiet reduce verbosity and only log issues found

Use -t/--timeout <value> to specify the socket timeout. The value should be high enough to conclude that the socket is hanging, but low enough to speed up testing (default: 5)

Use --no-color to suppress the output color codes printed to stdout (logs by default don't include color codes)

Use -c/--configfile <configfile> to specify your smuggler mutation configuration file (default: default.py)

Config Files

Configuration files are python files that exist in the ./config directory of smuggler. These files describe the content of the HTTP requests and the transfer-encoding mutations to test.

Here is example content of default.py:

def render_template(gadget):
	RN = "\r\n"
	p = Payload()
	p.header  = "__METHOD__ __ENDPOINT__?cb=__RANDOM__ HTTP/1.1" + RN
	# p.header += "Transfer-Encoding: chunked" +RN	
	p.header += gadget + RN
	p.header += "Host: __HOST__" + RN
	p.header += "User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.87 Safari/537.36" + RN
	p.header += "Content-type: application/x-www-form-urlencoded; charset=UTF-8" + RN
	p.header += "Content-Length: __REPLACE_CL__" + RN
	return p


mutations["nameprefix1"] = render_template(" Transfer-Encoding: chunked")
mutations["tabprefix1"] = render_template("Transfer-Encoding:\tchunked")
mutations["tabprefix2"] = render_template("Transfer-Encoding\t:\tchunked")
mutations["space1"] = render_template("Transfer-Encoding : chunked")

for i in [0x1,0x4,0x8,0x9,0xa,0xb,0xc,0xd,0x1F,0x20,0x7f,0xA0,0xFF]:
	mutations["midspace-%   02x"%i] = render_template("Transfer-Encoding:%cchunked"%(i))
	mutations["postspace-%02x"%i] = render_template("Transfer-Encoding%c: chunked"%(i))
	mutations["prespace-%02x"%i] = render_template("%cTransfer-Encoding: chunked"%(i))
	mutations["endspace-%02x"%i] = render_template("Transfer-Encoding: chunked%c"%(i))
	mutations["xprespace-%02x"%i] = render_template("X: X%cTransfer-Encoding: chunked"%(i))
	mutations["endspacex-%02x"%i] = render_template("Transfer-Encoding: chunked%cX: X"%(i))
	mutations["rxprespace-%02x"%i] = render_template("X: X\r%cTransfer-Encoding: chunked"%(i))
	mutations["xnprespace-%02x"%i] = render_template("X: X%c\nTransfer-Encoding: chunked"%(i))
	mutations["endspacerx-%02x"%i] = render_template("Transfer-Encoding: chunked\r%cX: X"%(i))
	mutations["endspacexn-%02x"%i] = render_template("Transfer-Encoding: chunked%c\nX: X"%(i))

There are no input arguments yet on specifying your own customer headers and user-agents. It is recommended to create your own configuration file based on default.py and modify it to your liking.

Smuggler comes with 3 configuration files: default.py (fast), doubles.py (niche, slow), exhaustive.py (very slow) default.py is the fastest because it contains less mutations.

specify configuration files using the -c/--configfile <configfile> command line option

Payloads Directory

Inside the Smuggler directory is the payloads directory. When Smuggler finds a potential CLTE or TECL desync issue, it will automatically dump a binary txt file of the problematic payload in the payloads directory. All payload filenames are annotated with the hostname, desync type and mutation type. Use these payloads to netcat directly to the server or to import into other analysis tools.

Helper Scripts

After you find a desync issue feel free to use my Turbo Intruder desync scripts found Here: https://github.com/defparam/tiscripts DesyncAttack_CLTE.py and DesyncAttack_TECL.py are great scripts to help stage a desync attack

License

These scripts are released under the MIT license. See LICENSE.

Download Smuggler

SUPREMA SEGURANÇA

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sexta-feira, 26 de janeiro de 2024

Linux Command Line Hackery Series - Part 6

How To Start | How To Become An Ethical Hacker

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quinta-feira, 25 de janeiro de 2024

Smuggler - An HTTP Request Smuggling / Desync Testing Tool

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