writing an exploit

4 Types of Exploits Used in Penetration Testing

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In modern-day operating systems such as the latest Linux distributions and Microsoft Windows, vulnerabilities are usually overly complex and subtle. When vulnerabilities are exploited by highly competent attackers, they can destabilize your organization’s security and expose you to critical damages. This is why you need advanced penetration testing training.

Only a few IT security analysts and cybersecurity professionals possess the skillset needed to detect why a complex vulnerability occurs and how to write an exploit to compromise it. Nevertheless, it is necessary to maintain this skillset irrespective of the heightened complexity.

The EC-Council Certified Penetration Testing Professional (CPENT) Program rewrites the standards of penetration testing skill development. It also teaches the skills you need to write complex exploits and conduct advanced binaries exploitation, how to pen test IoT systems and OT systems, how to build your own tools, how to double-pivot to access hidden networks, and also customize scripts or exploits to get into the deepest parts of the network.

What Is the Meaning of Exploit?

An exploit can be defined as a piece of software, code, or sequence of commands that takes advantage of a security flaw or software vulnerability to trigger an unintended or unexpected behavior to take place on hardware, operating system, computer software, networks, applications, or any computerized electronic system.

Exploits include payload and a chunk of code to introduce the payload into Vulnerable Application to steal network data or control computers. Exploit attacks allow an intruder to carry out actions like a denial-of-service (including a DoS or DDoS) attack, obtaining control of a computer system, moving deeper into a network, or granting privilege escalation.

In some situations, an exploit can be implemented as part of a multi-component attack. Nevertheless, not every single vulnerability needs to lead to the target being compromised.

What Is Binary Exploit?

Binary exploitation refers to the process of disrupting a compiled application in such a way that it infringes on some trust boundary and benefits the attacker. In short, binary exploitation operates on the notion of transforming weaknesses into an advantage.

For instance, in memory corruption, by exploiting the vulnerabilities that corrupt memory in software, attackers can frequently rewrite critical application state information in a manner that permits them to elevate privileges within the context of a specific application or execute arbitrary computation by running the code of their choice or hijacking control flow.

Types of Exploits

Exploits are typically categorized and named by the following

  • The type of vulnerability they exploit (such as BOF or Dangling Pointer)
  • Whether they are local or remote exploits: Local exploits are vulnerabilities that need to be performed on the same machine, while remote exploits are vulnerabilities exploited from a network at a distance.
  • It can also be the result of running the exploit (such as DoS, spoofing, the elevation of privilege, and so on).

At the highest level, we have two categories of computer exploits, which include both known and unknown exploits. Known exploits are ‘known’ to the system or software developers and brought to their notice through users or their own development team’s quality control process. Unknown exploits suggest that there is no documentation of this or any current solution. Zero-day attacks typically take advantage of this.

Further classifications include:

Heap Based Exploits

This exploit type involves placing a shellcode into a data input file, created to cause a vulnerability in the processing application. The heap is the memory pool where dynamic data requests are accomplished. Once an attacker enters the data in heap, it overflows the adjoining data residing in the heap’s lower segment.

Moreover, a heap overflow may be triggered if an application gets an input from the user and duplicates it in the memory without verifying it. It may often lead to arbitrary code execution, based on the data inserted by the attacker, leading to a system and application breach.

Stack Based Exploits

This is possibly the most common sort of exploit for remotely hijacking the code execution of a process. Stack-based buffer overflow exploits are triggered when the data above the stack space has been filled out. The stack refers to a chunk of the process memory or a data structure that operates LIFO (Last in first out).

The attackers can try to force some malicious code on the stack, which may redirect the program’s flow and perform the malicious program that the attacker intends to implement. The attacker does this by overwriting the return pointer so that the flow of control is passed to malicious code.

Integer Bug Exploits

Integer bugs occur due to programmers not foreseeing the semantics of C operations, which are often found and exploited by threat actors. The difference between integer bugs and other exploitation types is that they are often exploited indirectly. Likewise, the security costs of integer bugs are profoundly critical.

Since integer bugs are triggered indirectly, it enables an attacker to compromise other aspects of the memory, securing control over an application. Even if you resolve malloc errors, buffer overflows, or even format string bugs, many integer vulnerabilities would still be rendered exploitable. Integer bugs can typically be grouped into four broad categories, that is, underflows, overflows1, truncations, and signedness errors.

Format String Exploits

This exploit type occurs when the presented data of an input string is assessed as a command by the application. Format string exploits are implemented to execute malicious code, to collapse a software, or read the stack, which triggers new behaviors that can sabotage the stability or security of the system.

This exploit attack is viable since the user input is filtered as a format string parameter in some C functions that carry out formatting. Let’s assume a format string parameter, such as  %x, is inputted into the submitted data, the string will be evaluated by the format Function, and the conversion detailed in the parameters is performed.

Although, the format function will be anticipating more arguments as input, and if these arguments are not provided, the function could write or read the stack. In this case, a possibility to describe a well-constructed input exists, which could transform the behavior of the format function, allowing the attacker to trigger a DoS or to perform arbitrary commands.

Nevertheless, irrespective of the type of exploit an attacker executes, the aim is mostly the same: to obtain access or infect the system, software, hardware, operating system with malware.

Difference Between Vulnerability and Exploit

Vulnerability refers to the weakness or flaw within a software system which can be exploited by an attacker to perform unauthorized actions within a computer system. Vulnerability isn’t exactly an open door, but it is instead a weakness that could provide a way in if attacked.

On the other hand, an exploit is an attack that takes advantage of a vulnerability. In exploiting, an attacker tries to turn a vulnerability (or a weakness) into a real avenue to breach a system. Therefore, an attacker can ‘exploit’ a vulnerability by turning it into a practical technique to attack a system.

An attacker must have no less than one applicable tool or methodology that can connect to a system weakness before they can exploit a vulnerability. In this structure, vulnerabilities can likewise be referred to as the attack surface.

Defend your systems against exploits and vulnerabilities by learning how to perform penetration testing. To get started, sign up for EC-Council CPENT Program today!

How to Write Exploits

Before we list the steps for writing exploits, you should note that the programming language you write your exploits in isn’t of much importance. Learning how to exploit a vulnerability and learning about a programming language are two different things. It doesn’t really make much sense to learn how to write exploits in python alone even though python is a good language that you can use to write exploits. With that being said, the following are the basic steps to writing exploits:

  • Firstly, discover and evaluate applications for any vulnerability.
  • Next, connect it with a debugger and make attempts to find out if it is possible or impossible for you to overwrite the return value by offering particular input to the Vulnerable Application.
  • Afterward, if it is possible, try to automate this procedure by applying any scripting language like Python or Perl to simplify your work.
  • Finally, make attempts to discover an address from the DLL’s loaded in the ram where you can insert the Shellcode and import the execution flow to this address.

EC-Council Certified Penetration Testing Professional (CPENT) Program

The EC-Council’s Certified Penetration tester (CPENT) program gives you the hands-on training you need to know how to execute an efficient penetration test in an enterprise network environment that must be evaded, attacked, defended, and exploited. Likewise, the CPENT Challenge Edition is an affordable learning resource that offers a refresher in subjects such as IoT, binary analysis, SCADA, and ICS. To get details on plans and pricing, enroll now.

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