EVGalex

mercredi 20 mai 2020

inBINcible Writeup - Golang Binary Reversing

This file is an 32bits elf binary, compiled from go language (i guess ... coded by @nibble_ds ;)

The binary has some debugging symbols, which is very helpful to locate the functions and api calls.

GO source functions:

- main.main

- main.function.001

If the binary is executed with no params, it prints "Nope!", the bad guy message.

~/ncn$ ./inbincible

Nope!

Decompiling the main.main function I saw two things:

1. The Argument validation: Only one 16 bytes long argument is needed, otherwise the execution is finished.

2. The key IF, the decision to dexor and print byte by byte the "Nope!" string OR dexor and print "Yeah!"

The incoming channel will determine the final message.

Dexor and print each byte of the "Nope!" message.

This IF, checks 16 times if the go channel reception value is 0x01, in this case the app show the "Yeah!" message.

Go channels are a kind of thread-safe queue, a channel_send is like a push, and channel_receive is like a pop.

If we fake this IF the 16 times, we got the "Yeah!" message:

(gdb) b *0x8049118
(gdb) commands
>set {char *}0xf7edeef3 = 0x01
>c
>end

(gdb) r 1234567890123456
tarting program: /home/sha0/ncn/inbincible 1234567890123456
...
Yeah!

Ok, but the problem is not in main.main, is main.function.001 who must sent the 0x01 via channel.

This function xors byte by byte the input "1234567890123456" with a byte array xor key, and is compared with another byte array.

=> 0x8049456: xor %ebp,%ecx

This xor, encode the argument with a key byte by byte

The xor key can be dumped from memory but I prefer to use this macro:

(gdb) b *0x8049456
(gdb) commands
>i r ecx
>c
>end
(gdb) c

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x12 18

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x45 69

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x33 51

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x87 135

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x65 101

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x12 18

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x45 69

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x33 51

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x87 135

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x65 101

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x12 18

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x45 69

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x33 51

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x87 135

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x65 101

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x12 18

The result of the xor will compared with another array byte, each byte matched, a 0x01 will be sent.

The cmp of the xored argument byte,
will determine if the channel send 0 or 1

(gdb) b *0x0804946a
(gdb) commands
>i r al
>c
>end

At this point we have the byte array used to xor the argument, and the byte array to be compared with, if we provide an input that xored with the first byte array gets the second byte array, the code will send 0x01 by the channel the 16 times.

Now web have:

xorKey=[0x12,0x45,0x33,0x87,0x65,0x12,0x45,0x33,0x87,0x65,0x12,0x45,0x33,0x87,0x65,0x12]

mustGive=[0x55,0x75,0x44,0xb6,0x0b,0x33,0x06,0x03,0xe9,0x02,0x60,0x71,0x47,0xb2,0x44,0x33]

Xor is reversible, then we can get the input needed to dexor to the expected values in order to send 0x1 bytes through the go channel.

>>> x=''
>>> for i in range(len(xorKey)):
... x+= chr(xorKey[i] ^ mustGive[i])
...
>>> print x

G0w1n!C0ngr4t5!!

And that's the key :) let's try it:

~/ncn$ ./inbincible 'G0w1n!C0ngr4t5!!'
Yeah!

Got it!! thanx @nibble_ds for this funny crackme, programmed in the great go language. I'm also a golang lover.

More info

How To Install Metasploit In Termux

Evolving Logic Until Pass Tests Automatically

Automating the automation is still a challenge, but in some cases it's possible under certain situations.

In 2017 I created logic-evolver, one of my experiments for creating logic automatically or better said evolving logic automatically.

In some way, the computer create its own program that satisfies a set of tests defined by a human.

https://github.com/sha0coder/logic-evolver

This implementation in rust, contains a fast cpu emulator than can execute one million instructions in less than two seconds. And a simple genetic algorithm to do the evolution.

Here we create the genetic algorithm, and configure a population of 1000 individuals, and the top 5 to crossover. We run the genetic algorithm with 500 cycles maximum.
Note that in this case the population are programs initially random until take the correct shape.

An evaluation function is provided in the run method as well, and looks like this:

The evaluation function receives a CPU object, to compute a test you need to set the initial parameters, run the program and set a scoring regarding the return value.

Learning Web Pentesting With DVWA Part 6: File Inclusion

In this article we are going to go through File Inclusion Vulnerability. Wikipedia defines File Inclusion Vulnerability as: "A file inclusion vulnerability is a type of web vulnerability that is most commonly found to affect web applications that rely on a scripting run time. This issue is caused when an application builds a path to executable code using an attacker-controlled variable in a way that allows the attacker to control which file is executed at run time. A file include vulnerability is distinct from a generic directory traversal attack, in that directory traversal is a way of gaining unauthorized file system access, and a file inclusion vulnerability subverts how an application loads code for execution. Successful exploitation of a file inclusion vulnerability will result in remote code execution on the web server that runs the affected web application."
There are two types of File Inclusion Vulnerabilities, LFI (Local File Inclusion) and RFI (Remote File Inclusion). Offensive Security's Metasploit Unleashed guide describes LFI and RFI as:
"LFI vulnerabilities allow an attacker to read (and sometimes execute) files on the victim machine. This can be very dangerous because if the web server is misconfigured and running with high privileges, the attacker may gain access to sensitive information. If the attacker is able to place code on the web server through other means, then they may be able to execute arbitrary commands.
RFI vulnerabilities are easier to exploit but less common. Instead of accessing a file on the local machine, the attacker is able to execute code hosted on their own machine."
In simpler terms LFI allows us to use the web application's execution engine (say php) to execute local files on the web server and RFI allows us to execute remote files, within the context of the target web server, which can be hosted anywhere remotely (given they can be accessed from the network on which web server is running).
To follow along, click on the File Inclusion navigation link of DVWA, you should see a page like this:

Lets start by doing an LFI attack on the web application.
Looking at the URL of the web application we can see a parameter named page which is used to load different php pages on the website.

http://localhost:9000/vulnerabilities/fi/?page=include.php

Since it is loading different pages we can guess that it is loading local pages from the server and executing them. Lets try to get the famous /etc/passwd file found on every linux, to do that we have to find a way to access it via our LFI. We will start with this:

../etc/passwd

entering the above payload in the page parameter of the URL:

http://localhost:9000/vulnerabilities/fi/?page=../etc/passwd

we get nothing back which means the page does not exist. Lets try to understand what we are trying to accomplish. We are asking for a file named passwd in a directory named etc which is one directory up from our current working directory. The etc directory lies at the root (/) of a linux file system. We tried to guess that we are in a directory (say www) which also lies at the root of the file system, that's why we tried to go up by one directory and then move to the etc directory which contains the passwd file. Our next guess will be that maybe we are two directories deeper, so we modify our payload to be like this:

../../etc/passwd

we get nothing back. We continue to modify our payload thinking we are one more directory deeper.

../../../etc/passwd

no luck again, lets try one more:

../../../../etc/passwd

nop nothing, we keep on going one directory deeper until we get seven directories deep and our payload becomes:

../../../../../../../etc/passwd

which returns the contents of passwd file as seen below:

This just means that we are currently working in a directory which is seven levels deep inside the root (/) directory. It also proves that our LFI is a success. We can also use php filters to get more and more information from the server. For example if we want to get the source code of the web server we can use php wrapper filter for that like this:

php://filter/convert.base64-encode/resource=index.php

We will get a base64 encoded string. Lets copy that base64 encoded string in a file and save it as index.php.b64 (name can be anything) and then decode it like this:

cat index.php.b64 | base64 -d > index.php

We will now be able to read the web application's source code. But you maybe thinking why didn't we simply try to get index.php file without using php filter. The reason is because if we try to get a php file with LFI, the php file will be executed by the php interpreter rather than displayed as a text file. As a workaround we first encode it as base64 which the interpreter won't interpret since it is not php and thus will display the text. Next we will try to get a shell. Before php version 5.2, allow_url_include setting was enabled by default however after version 5.2 it was disabled by default. Since the version of php on which our dvwa app is running on is 5.2+ we cannot use the older methods like input wrapper or RFI to get shell on dvwa unless we change the default settings (which I won't). We will use the file upload functionality to get shell. We will upload a reverse shell using the file upload functionality and then access that uploaded reverse shell via LFI.
Lets upload our reverse shell via File Upload functionality and then set up our netcat listener to listen for a connection coming from the server.

nc -lvnp 9999

Then using our LFI we will execute the uploaded reverse shell by accessing it using this url:

http://localhost:9000/vulnerabilities/fi/?page=../../hackable/uploads/revshell.php

Voila! We have a shell.

To learn more about File Upload Vulnerability and the reverse shell we have used here read Learning Web Pentesting With DVWA Part 5: Using File Upload to Get Shell. Attackers usually chain multiple vulnerabilities to get as much access as they can. This is a simple example of how multiple vulnerabilities (Unrestricted File Upload + LFI) can be used to scale up attacks. If you are interested in learning more about php wrappers then LFI CheetSheet is a good read and if you want to perform these attacks on the dvwa, then you'll have to enable allow_url_include setting by logging in to the dvwa server. That's it for today have fun.
Leave your questions and queries in the comments below.

References:

FILE INCLUSION VULNERABILITIES: https://www.offensive-security.com/metasploit-unleashed/file-inclusion-vulnerabilities/
php://: https://www.php.net/manual/en/wrappers.php.php
LFI Cheat Sheet: https://highon.coffee/blog/lfi-cheat-sheet/
File inclusion vulnerability: https://en.wikipedia.org/wiki/File_inclusion_vulnerability
PHP 5.2.0 Release Announcement: https://www.php.net/releases/5_2_0.php

More information

How To Pass Your Online Accounts After Death – 3 Methods

The topic of DEATH is not one that most people care to talk about, but the truth is that we are all going to die at some point and everything that we did online is going to end up in limbo if we don't make sure that someone we trust is going to be able to gain access to this information. This is going to be extremely important in order to close it down, or have your loved one do whatever you want them to do with your information. There are many things to take into consideration for this kind of situation. If you are like the average modern person, you probably have at least one email account, a couple of social media accounts in places like Facebook and Twitter. Perhaps you also have a website that you run or a blog. These are all very common things that people will usually do at some point and if you have anything that you consider valuable, you should have a way to leave it in the hands of someone you trust when you pass away.

Pass Accounts and Passwords After Death

Maybe you have an online platform that has a lot of content that you find useful and important. Perhaps you have even been able to turn some of that content into monetizable material and you don't want this to end when you pass away. This is more than enough of a reason to make sure that your information can be given to someone when you are no longer around.

There have been many cases when all the information has ended up being impossible to recover when a person has died, at least not without the need for the family members to do all kinds of things in order to prove a person is deceased. So here are some ways, you can passyour online accounts/data after death:

1) Making a Safe 'WILL' (or Locker) containing master password.

Make an inventory of all your online accounts and list them on a piece of paper one by one and give it to your loved one. For eg:– Your primary email address
– Your Facebook ID/email
– The Bank account or Internet banking ID
– etc. To clarify, it will be only a list of the accounts you want your loved one to be able to access after you're dead. Just the list of accounts, nothing else (no passwords).
Set up a brand new e-mail address (Possibly Gmail account). Lets say youraccountsinfo@gmail.com
Now from your usual email account, Send an e-mail to youraccountsinfo@gmail.com, with the following content:– dd349r4yt9dfj
– sd456pu3t9p4
– s2398sds4938523540
– djfsf4p These are, of course, the passwords and account numbers that you want your loved one to have once you're dead.
Tell your loved one that you did these things, and while you're at it, send him/her an e-mail from youraccountsinfo@gmail.com, so he/she will have the address handy in some special folder in his/her inbox.
Put the password for youraccountsinfo@gmail.com in your will or write it down on paper and keep it safe in your bank locker. Don't include the e-mail address as well, just put something like "The password is: loveyourhoney432d".

And its done! Your loved one will only have the password once you're dead, and the info is also secure, since it's split in two places that cannot be easily connected, so if the e-mail address happens to be hacked, the perpetrator won't be able to use it to steal anything that you're going to leave for your loved one.

2) Preparing a Future email (SWITCH) containing login information

This method is very similar to the first one except in this case we will not be using a WILL or Locker. Instead we will be using a Service called "Dead Mans Switch" that creates a switch (Future email) and sends it to your recipients after a particular time interval. Here is how it works.

Create a list of accounts as discussed in the first method and give it to your loved one.
Register on "Dead mans switch" and create a switch containing all the corresponding passwords and enter the recipients email (Your loved one).
Your switch will email you every so often, asking you to show that you are fine by clicking a link. If something happens to you, your switch would then send the email you wrote to the recipient you specified. Sort of an "electronic will", one could say.

3) Using password managers that have emergency access feature

Password managers like LastPass and Dashlane have a feature called as "emergency access". It functions as a dead man's switch. You just have to add your loved one to your password manager, with emergency access rights. he/She does not see any of your information, nor can he/she log into your accounts normally.

But if the worst happens, your loved one can invoke the emergency access option. Next your password manager sends an email to you and starts a timer. If, after a certain amount of time interval, you have not refused the request, then your loved one gets full access to your password manager.

You can always decide what they can potentially gain access to, and you set the time delay.

Why should i bother about passing my digital legacy?

Of all the major online platforms, only Google and Facebook have provisions for Inactiveaccounts (in case of death). Google lets you plan for the inevitable ahead of time. Using the "Inactive Account Manager", you can designate a beneficiary who will inherit access to any or all of your Google accounts after a specified period of inactivity (the default is 3 months).

Facebook on the other hand will either delete your inactive account or turn it into a memorial page when their family can provide any proof of their death, but there is also a large number of platforms that don't have any specific way for people to be able to verify the death of a loved one in order to gain access to the accounts. In either case, you wouldn't want your family to have to suffer through any hassles and complications after you have passed away.

You should also consider the importance of being able to allow your loved ones to collect all the data you left behind. This means photos and experiences that can be used to show other generations the way that you lived and the kind of things you enjoyed doing.

Those memories are now easier to keep and the best photos can be downloaded for the purpose of printing them for photo albums or frames. Allowing them to have the chance to do this in a practical way is going to be a great gesture and securing any profitable information is going to be essential if you want a business or idea to keep moving forward with the help of those you trust.

This is the reason why you need to be able to pass your online account information after death, but no one wants to give access to this kind of information to their loved ones because it's of a private nature and we would feel uneasy knowing that others can access our private conversations or message.

More info

TYPES OF HACKER

7 Types of hacker

1-Script Kiddies-They are just download overused software & watch youtube video on how to use it. Script kiddies don't care about hacking.

2-White Hat-They are the good guys of the hacker world. They also known as Ethical Hacker.

3-Black Hat-They finds bank or other companies with weak security and steal money or credit card information. They also known as cracker. They are dangerous because they are illegal to gain unauthorized access.

4-Gray Hat-They don't steal money or information sometimes they deface a website or they don't help people for good.

5-Green Hat-These are the hacker "noobz" but unlike Script Kiddies.They care about Hacking and strive to become full-blown hacker.

6-Red Hat-These are the vigilantes of the hacker world. They are like White Hats in that they halt Black Hats but these folks are downright SCARY to those who have ever tried so much as penetrest.

7-Blue Hat-If a Script Kiddy took revenge he/she might become a Blue Hat.Most Blue Hats are noobz.They have no desire to learn.

Related word

Files Download Information

After 7 years of Contagio existence, Google Safe Browsing services notified Mediafire (hoster of Contagio and Contagiominidump files) that "harmful" content is hosted on my Mediafire account.

It is harmful only if you harm your own pc and but not suitable for distribution or infecting unsuspecting users but I have not been able to resolve this with Google and Mediafire.

Mediafire suspended public access to Contagio account.

The file hosting will be moved.

If you need any files now, email me the posted Mediafire links (address in profile) and I will pull out the files and share via other methods.

P.S. I have not been able to resolve "yet" because it just happened today, not because they refuse to help. I don't want to affect Mediafire safety reputation and most likely will have to move out this time.

The main challenge is not to find hosting, it is not difficult and I can pay for it, but the effort move all files and fix the existing links on the Blogpost, and there are many. I planned to move out long time ago but did not have time for it. If anyone can suggest how to change all Blogspot links in bulk, I will be happy.

P.P.S. Feb. 24 - The files will be moved to a Dropbox Business account and shared from there (Dropbox team confirmed they can host it )

The transition will take some time, so email me links to what you need.

Thank you all
M