Introduction to Buffer Overflow
A buffer is a storage area within the computing memory that temporarily stores data while being shifted from one location to another. A buffer overflow occurs when the buffer exceeds its data storage capacity causing data leaks and security vulnerabilities. Even though buffer overflow is a well-known and comprehended concept, buffer overflow attack remains a major challenge for cyber security experts. Let’s understand about this attack in detail here.
What is a Buffer Overflow Attack?
The extra data that overflows from the buffer often runs a high risk of being corrupted and overwritten. This leads to a buffer overflow attack which is when a hacker manipulates the data to damage sensitive files, compromise the company’s private information, or more.
There are two main types of buffer overflow attacks as mentioned below:
- Stack-based Attack
- Heap-based Attack
Stack-based attack is the most common buffer overflow attack. In this, the hacker deliberately sends more data to the application than it can hold. This allows the attacker to overwrite data and gain complete control of the program.
A heap-based attack is more complex to perform. Here, the buffer to be overwritten is allocated a significant amount of additional memory. When the attacker feeds more data to the extra space, the damage occurs including overwriting the internal structures.
Buffer Overflow Attack Exploitation
Buffer overflow attack focuses on the buffer data, allowing attackers to replace the additional data with carefully designed codes. By doing so, they can either control the entire program or manipulate codes to perform malicious activities on the system.
In case the hacker is familiar with the program’s memory layout, they can themselves add data that cannot be stored by the buffer. This allows them to overwrite the executable codes to rewrite the program in whatever way they want.
The vulnerability of buffer overflow attacks is higher in certain languages including C and C++. Modern coding languages such as Java are less susceptible to this attack as they incorporate advanced features that prevent such security vulnerabilities.
How to Prevent a Buffer Overflow Attack?
Advanced security measures taken during the application development process will prevent buffer overflow. Here are a few common prevention methods you must follow.
- Address Space Layout Randomization (ASLR)
- Structured Exception Handling Overwrite Protection (SEHOP)
- Secure Coding and Regular Updates
- Use Memory-safe Languages
- Data Execution Prevention (DEP)
Buffer overflow attacks need to know the exact location of the system executables. Address Space Layout Randomization or ASLR is a process that randomly moves the location of these executables’ codes making them difficult for attackers to locate.
Structured exception handling is an in-built extension for managing hardware and software exceptions that hackers look to attack. The SEHOP mechanism is a prevention method that detects and overwrites the codes attacking these exception-handling structures.
Ensure you adopt a secure coding approach like using safe functions and memory-safe languages to mitigate risks such as buffer overflow attacks. Moreover, regularly update your software to keep it up-to-date and avoid potential security vulnerabilities.
A buffer overflow attack generally targets a language with no memory protection. Therefore, it’s ideal to choose memory-safe languages such as Python or Java from the beginning. This significantly reduces the threat of a buffer overflow attack.
Data execution prevention is a modern technology that lets you flag areas within the memory as executable and non-executable. This protects your system from buffer overflow attacks as hackers won’t be able to run codes in the non-executable regions.