Causes of Buffer Overflows

B.

Buffer Overflow attack takes advantage of improper parameter checking within the application.This is the classic form of buffer overflow and occurs because the programmer accepts whatever input the user supplies without checking to make sure that the length of the input is less than the size of the buffer in the program.

The buffer overflow problem is one of the oldest and most common problems in software development and programming, dating back to the introduction of interactive computing.

It can result when a program fills up the assigned buffer of memory with more data than its buffer can hold.

When the program begins to write beyond the end of the buffer, the programs execution path can be changed, or data can be written into areas used by the operating system itself.

This can lead to the insertion of malicious code that can be used to gain administrative privileges on the program or system.

As explained by Gaurab,it can become very complex.At the time of input even if you are checking the length of the input, it has to be check against the buffer size.Consider a case where entry point of data is stored in Buffer1 of Application1 and then you copy it to Buffer2 within Application2 later on,if you are just checking the length of data against Buffer1, it will not ensure that it will not cause a buffer overflow in Buffer2 of Application2

A bit of reassurance from the ISC2 book about level of Coding Knowledge needed for the exam: It should be noted that the CISSP is not required to be an expert programmer or know the inner workings of developing application software code, like the FORTRAN programming language, or how to develop Web applet code using Java.

It is not even necessary that the CISSP know detailed security-specific coding practices such as the major divisions of buffer overflow exploits or the reason for preferring str(n)cpy to strcpy in the C language (although all such knowledge is, of course, helpful)

Because the CISSP may be the person responsible for ensuring that security is included in such developments, the CISSP should know the basic procedures and concepts involved during the design and development of software programming.

That is, in order for the CISSP to monitor the software development process and verify that security is included, the CISSP must understand the fundamental concepts of programming developments and the security strengths and weaknesses of various application development processes.

The following are incorrect answers: "Because buffers can only hold so much data" is incorrect.This is certainly true but is not the best answer because the finite size of the buffer is not the problem -- the problem is that the programmer did not check the size of the input before moving it into the buffer.

"Because they are an easy weakness to exploit" is incorrect.This answer is sometimes true but is not the best answer because the root cause of the buffer overflow is that the programmer did not check the size of the user input.

"Because of insufficient system memory" is incorrect.This is irrelevant to the occurrence of a buffer overflow.

Reference(s) used for this question: Hernandez CISSP, Steven (2012-12-21)

Official (ISC)2 Guide to the CISSP CBK, Third Edition ((ISC)2 Press) (Kindle Locations 13319-13323)

Auerbach Publications.

Kindle Edition.

Buffer overflow is a common type of vulnerability that occurs when a program or process attempts to store more data in a buffer than it can hold. A buffer is a temporary storage area in a computer's memory that holds data while it is being processed or transferred from one location to another.

The main cause of buffer overflows is insufficient bounds checking or parameter validation within the application's code. When a program reads data into a buffer, it may not check the size of the data being read to ensure that it does not exceed the allocated buffer size. This can result in data being written beyond the buffer's allocated memory space, potentially overwriting other important data or even causing the program to crash or behave unexpectedly.

Attackers can exploit buffer overflow vulnerabilities by providing more data than the buffer can hold, with the intention of overwriting adjacent memory locations. This can allow attackers to execute malicious code, gain unauthorized access to system resources, or cause the program to crash, which can be leveraged to take control of the system.

Therefore, it is essential to implement proper input validation and bounds checking in applications to prevent buffer overflows. Additionally, developers should use secure coding practices and follow coding standards to minimize the risk of buffer overflow vulnerabilities. System administrators should also ensure that operating systems and applications are regularly patched and updated to address known vulnerabilities.