A Buffer Overflow is an anomaly that causes software that writes data to a buffer to overwrite adjacent memory locations by exceeding the buffer's capacity. In other words, too much information is being transferred to a container that doesn't have enough space, and that information is replacing the data in adjacent containers.
Buffer Overflow can be exploited by attackers to modify a computer's memory or to take control of program execution.
What is Buffer?
A buffer, or data buffer, is a physical memory storage that is used to temporarily store data as it moves from one place to another. These buffers typically reside in RAM memory. Computers frequently use buffers to help improve performance; most modern hard drives rely on buffering to access data efficiently, and many online services also use buffers. For example, buffers are often used in online video streaming to avoid interruption. When a video is streamed, the video player downloads and stores perhaps 20% of the video in a buffer at a time, and then streams through that buffer. In this way, small drops in connection speed or fast service interruptions will not affect the video streaming performance.
Buffers are designed to contain a certain amount of data. If the program using the buffer does not have built-in instructions for discarding data when too much is sent to the buffer, the program will overwrite the data in memory adjacent to the buffer.
Buffer overruns can be used by attackers to corrupt software. Although well understood, buffer overflow attacks are still a major security issue that torments cybersecurity teams. In 2014, a threat known as 'heart bleeding' caused hundreds of millions of users to be hacked due to a buffer overflow vulnerability in SSL software.
How do attackers take advantage of buffer Overflow?
An attacker could feed a deliberately crafted input into a program in such a way that the program attempts to store this entry in an insufficiently large buffer and overwrites portions of memory that are bound to the buffer space. If the program's memory layout is well defined, an attacker could intentionally overwrite areas that are known to contain executable code. The attacker could then replace this code with his own executable code, which could greatly alter the way the program runs.
For example, if the overwritten portion of memory contains a pointer (an object pointing to another location in memory), the attacker's code might replace that code with another pointer pointing to an exploit payload. This can transfer control of the entire program to the attacker's code.
Who is vulnerable to buffer overflow attacks?
Some coding languages are more susceptible to buffer overrun than others. C and C++ are two popular languages with high security vulnerabilities because they do not include built-in protection against accessing or overwriting data in their memory. Windows, Mac OSX, and Linux all contain code written in one or both of these languages.
More modern languages such as Java, PERL, and C# have built-in features that help reduce the likelihood of buffer overruns, but can't prevent this entirely.
How to protect against buffer overflow attacks
Fortunately, modern operating systems have runtime protections that help mitigate buffer overflow attacks. Let's examine 2 common protections that help reduce the risk of exploitation:
Address space randomization - Randomly rearranges the address space positions of an operation's key data fields. Buffer overflow attacks often rely on knowing the exact location of important executable code, randomizing address spaces makes this nearly impossible.
Data execution prevention – Prevents an exploit from running code that is located in a non-executable area by marking specific areas of executable or non-executable memory.
Software developers can also counter buffer overflow vulnerabilities by writing in languages that have built-in protections or by using special security procedures in their code.
Despite the precautions, new buffer overflow vulnerabilities continue to be discovered by developers, sometimes after a successful exploit. When new vulnerabilities are discovered, engineers need to fix the affected software and ensure that software users have access to the patch.
Subject: https://www.turkhackteam.org/konular/what-is-buffer-overflow.2019298/
Buffer Overflow can be exploited by attackers to modify a computer's memory or to take control of program execution.
What is Buffer?
A buffer, or data buffer, is a physical memory storage that is used to temporarily store data as it moves from one place to another. These buffers typically reside in RAM memory. Computers frequently use buffers to help improve performance; most modern hard drives rely on buffering to access data efficiently, and many online services also use buffers. For example, buffers are often used in online video streaming to avoid interruption. When a video is streamed, the video player downloads and stores perhaps 20% of the video in a buffer at a time, and then streams through that buffer. In this way, small drops in connection speed or fast service interruptions will not affect the video streaming performance.
Buffers are designed to contain a certain amount of data. If the program using the buffer does not have built-in instructions for discarding data when too much is sent to the buffer, the program will overwrite the data in memory adjacent to the buffer.
Buffer overruns can be used by attackers to corrupt software. Although well understood, buffer overflow attacks are still a major security issue that torments cybersecurity teams. In 2014, a threat known as 'heart bleeding' caused hundreds of millions of users to be hacked due to a buffer overflow vulnerability in SSL software.
How do attackers take advantage of buffer Overflow?
An attacker could feed a deliberately crafted input into a program in such a way that the program attempts to store this entry in an insufficiently large buffer and overwrites portions of memory that are bound to the buffer space. If the program's memory layout is well defined, an attacker could intentionally overwrite areas that are known to contain executable code. The attacker could then replace this code with his own executable code, which could greatly alter the way the program runs.
For example, if the overwritten portion of memory contains a pointer (an object pointing to another location in memory), the attacker's code might replace that code with another pointer pointing to an exploit payload. This can transfer control of the entire program to the attacker's code.
Who is vulnerable to buffer overflow attacks?
Some coding languages are more susceptible to buffer overrun than others. C and C++ are two popular languages with high security vulnerabilities because they do not include built-in protection against accessing or overwriting data in their memory. Windows, Mac OSX, and Linux all contain code written in one or both of these languages.
More modern languages such as Java, PERL, and C# have built-in features that help reduce the likelihood of buffer overruns, but can't prevent this entirely.
How to protect against buffer overflow attacks
Fortunately, modern operating systems have runtime protections that help mitigate buffer overflow attacks. Let's examine 2 common protections that help reduce the risk of exploitation:
Address space randomization - Randomly rearranges the address space positions of an operation's key data fields. Buffer overflow attacks often rely on knowing the exact location of important executable code, randomizing address spaces makes this nearly impossible.
Data execution prevention – Prevents an exploit from running code that is located in a non-executable area by marking specific areas of executable or non-executable memory.
Software developers can also counter buffer overflow vulnerabilities by writing in languages that have built-in protections or by using special security procedures in their code.
Despite the precautions, new buffer overflow vulnerabilities continue to be discovered by developers, sometimes after a successful exploit. When new vulnerabilities are discovered, engineers need to fix the affected software and ensure that software users have access to the patch.
Subject: https://www.turkhackteam.org/konular/what-is-buffer-overflow.2019298/
