BROP - Blind Return Oriented Programming

👉 Overview

👀 What ?

Blind Return Oriented Programming (BROP) is an attack technique that allows an attacker to construct a program to exploit a vulnerability in software without prior knowledge of the binary or source code being used. This technique is particularly powerful as it enables attackers to circumvent common modern security defenses, such as Address Space Layout Randomization (ASLR).

🧐 Why ?

BROP is a significant threat due to its ability to bypass common security measures. It's a sophisticated technique that requires a deep understanding of computer architecture and memory management, making it a tool of choice for advanced threat actors. Understanding BROP is important for anyone involved in cybersecurity, as it provides insights into how complex attacks can be orchestrated and how to develop appropriate defensive strategies.

⛏️ How ?

To use BROP, an attacker will typically cause a buffer overflow on the target system, which allows the attacker to overwrite the return address of a function. The attacker then uses a trial and error process, known as 'blinding', to find sequences of code, or 'gadgets', that can be chained together to form a malicious program. The attacker then injects these gadgets into the system's memory, causing the system to execute the attacker's code.

⏳ When ?

The concept of Return Oriented Programming was first introduced in 1997, but the term 'Blind Return Oriented Programming' was coined in a 2014 research paper by researchers from Stanford University and the University of Texas. Since then, it has become a common technique used in sophisticated cyber attacks.

⚙️ Technical Explanations

Blind Return Oriented Programming (BROP) is a sophisticated attack technique that poses a significant threat to computer systems. The process involves the exploitation of a buffer overflow vulnerability, which occurs when a program writes more data to a buffer than it can hold, causing an overflow.

In the case of BROP, this overflow is used to overwrite the return address of a function. The return address is a part of a function that indicates where the function should go back to once it has completed its task. By overwriting this, the attacker can redirect the flow of the program execution to a location of their choosing.

The next step involves a technique known as 'blinding'. This is a trial and error process that the attacker uses to find useful sequences of code, also known as 'gadgets', in the binary. A binary is a compiled computer program and is composed of machine code, the basic instructions that a computer can understand.

These gadgets are snippets of code that end in a 'return' instruction - hence the name 'Return Oriented Programming'. The end goal is to find and chain together these gadgets in such a way as to create a new program that can be used for malicious purposes.

Once the attacker has located the necessary gadgets and ordered them correctly in the system's memory, they effectively have a malicious program. When this program is executed by the system, the attacker gains control over it. This makes BROP a potent tool for attackers, as it allows them to bypass common security measures and gain control over a system without needing to understand the binary or source code in use.

While it's not ethical or legal to provide a real-world example of executing a BROP attack due to its malicious nature, I can provide a simplified, hypothetical scenario to illustrate how it might work:

1. Buffer Overflow: Let's say we have a simple program that takes user input without properly checking its length. If the input is too long, it can overflow the buffer and overwrite the return address of the function.

#include <stdio.h>
#include <string.h>

void vulnerable_function(char* string) {
    char buffer[100];
    strcpy(buffer, string);
}

int main() {
    char too_long_string[200];
    memset(too_long_string, 'A', 199);
    too_long_string[199] = '\\0';
    vulnerable_function(too_long_string);
    return 0;
}

In this hypothetical C program, the vulnerable_function does not check the length of the input string before copying it to the buffer. If a string longer than 100 characters is provided, it will overflow the buffer.

1. Finding Gadgets: The attacker would then use a tool like ROPgadget to analyze the binary and find useful gadgets. This step is complex and requires deep knowledge of assembly language and computer architecture.

ROPgadget --binary vulnerable_program

1. Chaining Gadgets: The attacker would analyze the output of the above command to find useful gadgets and understand how they can be chained together to form a malicious payload. This would typically be done in a controlled environment, using a tool like gdb to analyze the program's memory.
2. Executing the Attack: The attacker will then craft an input that overflows the buffer, overwrites the return address with the address of the first gadget, and includes the addresses of the subsequent gadgets. When the vulnerable function returns, it will start executing the attacker's code.

Please note that this is a simplified explanation and real-world BROP attacks are more complex and involve additional steps and challenges. Also, the above example is theoretical and should not be used to conduct real attacks.