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How do I get started with bug bounty hunting? How do I improve my skills?

These are some simple steps that every bug bounty hunter can use to get started and improve their skills:

Learn to make it; then break it!
A major chunk of the hacker's mindset consists of wanting to learn more. In order to really exploit issues and discover further potential vulnerabilities, hackers are encouraged to learn to build what they are targeting. By doing this, there is a greater likelihood that hacker will understand the component being targeted and where most issues appear. For example, when people ask me how to take over a sub-domain, I make sure they understand the Domain Name System (DNS) first and let them set up their own website to play around attempting to "claim" that domain.

Read books. Lots of books.
One way to get better is by reading fellow hunters' and hackers' write-ups. Follow /r/netsec and Twitter for fantastic write-ups ranging from a variety of security-related topics that will not only motivate you but help you improve. For a list of good books to read, please refer to "What books should I read?".

Join discussions and ask questions.
As you may be aware, the information security community is full of interesting discussions ranging from breaches to surveillance, and further. The bug bounty community consists of hunters, security analysts, and platform staff helping one and another get better at what they do. There are two very popular bug bounty forums: Bug Bounty Forum and Bug Bounty World.

Participate in open source projects; learn to code.
Go to https://github.com/explore or https://gitlab.com/explore/projects and pick a project to contribute to. By doing so you will improve your general coding and communication skills. On top of that, read https://learnpythonthehardway.org/ and https://linuxjourney.com/.

Help others. If you can teach it, you have mastered it.
Once you discover something new and believe others would benefit from learning about your discovery, publish a write-up about it. Not only will you help others, you will learn to really master the topic because you can actually explain it properly.

Smile when you get feedback and use it to your advantage.
The bug bounty community is full of people wanting to help others so do not be surprised if someone gives you some constructive feedback about your work. Learn from your mistakes and in doing so use it to your advantage. I have a little physical notebook where I keep track of the little things that I learnt during the day and the feedback that people gave me.

Learn to approach a target.
The first step when approaching a target is always going to be reconnaissance — preliminary gathering of information about the target. If the target is a web application, start by browsing around like a normal user and get to know the website's purpose. Then you can start enumerating endpoints such as sub-domains, ports and web paths.

A woodsman was once asked, "What would you do if you had just five minutes to chop down a tree?" He answered, "I would spend the first two and a half minutes sharpening my axe."
As you progress, you will start to notice patterns and find yourself refining your hunting methodology. You will probably also start automating a lot of the repetitive tasks.

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Rushaidin

Rushaidin

"DMitry (Deepmagic Information Gathering Tool) is a UNIX/(GNU)Linux Command Line Application coded in C. DMitry has the ability to gather as much information as possible about a host. Base functionality is able to gather possible subdomains, email addresses, uptime information, tcp port scan, whois lookups, and more." read more...

Download: http://packetstormsecurity.org/UNIX/misc/DMitry-1.2a.tar.gz

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Rushaidin

There are many goodware and malware developed in pascal, and we will see that the binary generated by the pascal compilers is fascinating, not only because the small and clean generated binaries, or the clarity of the pascal code, but also the good performance. In Linux we have Lazarus which is a good free IDE like Delphi and Kylix the free pascal IDE for windows.

The program:

program strtest;

var
cstr: array[0..10] of char;
s, s2: ShortString;

begin
cstr := 'hello world';
s := cstr;
s2 := 'test';

WriteLn(cstr + ' ' + s + ' ' + s2);
end.

We are going to compile it with freepascal and lazarus, and just the binary size differs a lot:

lazarus 242,176 btytes 845 functions
freepascal 32,256 bytes 233 functions
turbopascal 2,928 bytes 80 functions (wow)

And surprisingly turbopascal binaries are extremely light.
Lets start with lazarus:

Logically it imports from user32.dll some display functions, it also import the kernel32.dll functions and suspiciously the string operations of oleaut32.dll

And our starting point is a function called entry that calls the console initialization and retrieve some console configurations, and then start a labyrinth of function calls.

On functions 10000e8e0 there is the function that calls the main function.

I named execute_param2 because the second param is a function pointer that is gonna be executed without parameters, it sounds like main calling typical strategy.
And here we are, it's clearly the user code pascal main function.

What it seems is that function 100001800 returns an string object, then is called its constructor to initialize the string, then the string is passed to other functions that prints it to the screen.

This function executes the method 0x1c0 of the object until the byte 0x89 is a null byte.
What the hell is doing here?
First of all let's create the function main:

Simply right button create function:

After a bit of work on Ghidra here we have the main:

Note that the struct member so high like 0x1b0 are not created by default, we should import a .h file with an struct or class definition, and locate the constructor just on that position.

The mysterious function was printing byte a byte until null byte, the algorithm the compiler implemented in asm is not as optimized as turbopascal's.

In Windbg we can see the string object in eax after being created but before being initialized:

Just before executing the print function, the RCX parameter is the string object and it still identical:

Let's see the constructor code.
The constructor address can be guessed on static walking the reverse-cross-references to main, but I located it in debugging it in dynamic analysis.

The constructor reads only a pointer stored on the string object on the position 0x98.

And we have that the pointer at 0x98 is compared with the address of the literal, so now we know that this pointer points to the string.
The sentence *string_x98 = literal confirms it, and there is not memory copy, it only points reusing the literal.

Freepascal

The starting labyrinth is bigger than Lazarus so I had to begin the maze from the end, searching the string "hello world" and then finding the string references:

There are two ways to follow the references in Ghidra, one is [ctrl] + [shift] + F but there is other trick which is simply clicking the green references texts on the disassembly.

At the beginning I doubted and put the name possible_main, but it's clearly the pascal user code main function.

The char array initialization Is converted by freepascal compiler to an runtime initialization using mov instructions.

Reducing the coverage on dynamic we arrive to the writeln function:

EAX helds a pointer to a struct, and the member 0x24 performs the printing. In this cases the function can be tracked easily in dynamic executing the sample.

And lands at 0x004059b0 where we see the WriteFile, the stdout descriptor, the text and the size supplied by parameter.

there is an interesting logic of what happens if WriteFile() couldn't write all the bytes, but this is other scope.
Lets see how this functions is called and how text and size are supplied to figure out the string object.

EBX helds the string object and there are two pointers, a pointer to the string on 0x18 and the length in 0x18, lets verify it on windbg.

And here we have the string object, 0x0000001e is the length, and 0x001de8a68 is the pointer.

Thanks @capi_x for the pascal samples.

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Sunday, January 28, 2024

How Do I Get Started With Bug Bounty ?

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Malware Arsenal Used By Ember Bear (Aka UAC-0056,Saint Bear, UNC2589, Lorec53, TA471, Nodaria, Nascent Ursa, LorecBear, Bleeding Bear, And DEV-0586) In Attacks Targeting Ukraine (Samples)

DMitry: Deepmagic Information Gathering Tool

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Saturday, January 27, 2024

Reversing Pascal String Object

Freepascal

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