buffer overflow

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buffer overflow

(programming)
What happens when you try to store more data in a buffer than it can handle. This may be due to a mismatch in the processing rates of the producing and consuming processes (see overrun and firehose syndrome), or because the buffer is simply too small to hold all the data that must accumulate before a piece of it can be processed. For example, in a text-processing tool that crunches a line at a time, a short line buffer can result in lossage as input from a long line overflows the buffer and overwrites data beyond it. Good defensive programming would check for overflow on each character and stop accepting data when the buffer is full.

See also spam, overrun screw.

buffer overflow

A common cause of malfunctioning software. If the amount of data copied into a memory buffer exceeds the size of the buffer, the extra data will overwrite whatever is in the adjacent bytes, and those bytes could hold numbers and codes the program constantly uses (see flag and variable). It only takes an error of one bit to crash software.

Certain copy instructions transfer strings of data within memory until some character such as a null or return is reached, signaling its end. Such instructions are potentially dangerous and can be avoided by using instructions that copy a fixed number of bytes.

Buffer Overruns Are Exploited
If software is written to assume the correct amount of data will always be input and makes no provisions otherwise, malicious hackers can exploit this situation by entering more and more data until the computer crashes. When it does, the computer's registers are examined to find out if it was attempting to execute an instruction in the overrun buffer area and if so, the precise location. The exploit is then carried out by appending machine instructions at the end of the input that the computer will execute. See XSS and SQL injection.

Slammer Wreacked Havoc
In January 2003, the Slammer worm on the Internet caused a billion dollars worth of damage. Using randomly generated IP addresses, Slammer used the buffer overflow exploit to replicate itself. Within three minutes after the first Slammer packet was unleashed, the number of infected computers was doubling every eight seconds. Within 15 minutes, large sections of the Internet were overloaded and out of commission. See buffer and buffer flush.
References in periodicals archive ?
It will drop packets at the end of the queue when buffer overflows. Therefore, "drop tail" is a passive queue management method.
At its launch, the Help AG Hackademy comprises of five courses that cover several aspects of ethical hacking including internal and external penetration testing, assessment of web applications, simulating social engineering attacks, and executing advanced hacking techniques such as buffer overflows and reverse engineering.
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Common attacks, such as XSS and buffer overflows, all exploit software vulnerabilities; thus vulnerability analysis attracts extensive research during the past decade.
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For example, by removing the need for developers to directly allocate memory, Java and .NET eliminate almost entirely vulnerabilities dealing with memory allocation (such as buffer overflows).
New to Fedora 23 is a hardening of these packages through the use of compiler flags, helping to prevent corruption, buffer overflows and other vulnerability issues.
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Thus, both PRR and IEG only can identify the link failures after the buffer overflows already occurred.
Tail drop problems are caused by buffer overflows, and the delayed reaction to congestion.
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