Understanding Buffer Overflow Attack

November 23, 2022

Data is temporarily stored in buffer areas of memory while being transported from one place to another. A buffer overflow occurs when data exceeds the memory buffer’s storage capacity. The application that is trying to copy the data to the pad, as a result, overwrites nearby memory regions.

If a transaction contains an input of 10 bytes, the software may write the extra data over the buffer border. For instance, a buffer for log-in credentials may be constructed to anticipate username and password inputs of 8 bytes.

All forms of software are susceptible to buffer overflows. They often happen due to incorrect inputs or inadequate buffer space allocation. The software may perform erratically, provide inaccurate results, make memory access mistakes, or crash if the transaction overwrites executable code.

Buffer Overflow Attack Definition

Attackers use program memory overwriting to take advantage of buffer overflow vulnerabilities. Altering the program’s execution path might cause reactions that corrupt files or reveal sensitive information. For instance, a hacker can add more code and give the program brand-new instructions to access IT systems.

If an attacker is aware of a program’s memory structure, they may purposefully enter data that the buffer is not designed to retain. They can even rewrite regions that contain executable code with their code. For instance, to take control of the application, an attacker may rewrite a pointer an object that links to another location in memory—and direct it to the exploit payload.

Buffer Overflow Attacks: Types

More often occurring, stack-based buffer overflows make use of stack memory, which is only available while a function is being executed. Heap-based attacks are more challenging to achieve, which entails flooding the memory space allotted for a program beyond the RAM required for current runtime activities.

What Are Languages of Programming More Vulnerable?

Due to the lack of built-in protections against overwriting or accessing memory data, C and C++ are two languages that are particularly vulnerable to buffer overflow attacks. Mac OS X, Windows, and Linux use code produced in C and C++. Buffer overflow is less likely to occur when using built-in safety features in languages like PERL, Java, JavaScript, and C#.

Methods for Avoiding Buffer Overflows

By incorporating security features into their code or employing programming languages with built-in protection, developers may guard against buffer overflow vulnerabilities. Runtime protection is another feature of modern operating systems. There are three typical safeguards: Address space randomization (ASLR) shuffles the locations of data regions’ address spaces. Buffer overflow attacks often need knowledge of the area of executable code, which is almost impossible when address spaces are randomly generated.

Data execution prevention prevents an attack from executing code in a non-executable zone by designating certain memory regions as executable or non-executable. The built-in method for handling hardware and software exceptions, Structured Exception Handling (SEH), is guarded against assault by malicious code thanks to Structured Exception Handler Overwrite Protection (SEHOP). Thus, an attacker can’t use the SEH overwrite exploitation approach. Functionally, an SEH overwrite is accomplished by overwriting an exception registration record on a thread’s stack via a stack-based buffer overflow.

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Sam Fareed

Lead Instructor qualified in CISSP, CCIE, and MCT with 25 years of training experience in Toronto.