buffer overflow

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buffer overflow

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.

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 ?
29 /PRNewswire/ -- FaceTime Communications, the leading provider of solutions that secure, manage, and extend instant messaging (IM) and peer-to-peer (P2P) applications, today warned of a new IM and P2P security threat that is leveraging a buffer overrun vulnerability in the processing of JPEG image formats that could allow remote code execution on an affected system.
MS04-028 -- Buffer Overrun in JPEG Processing Could Allow Code Execution (833987)
The MS04-025 bulletin includes three vulnerabilities, which consist of a Navigation Method Cross-Domain vulnerability, a Malformed BMP File Buffer Overrun vulnerability and a Malformed GIF Double Free vulnerability.
a leader in network antivirus and Internet content security software and services, today warns of a family of new worms, referred to as "WORM_SASSER" that spreads by scanning for random IP addresses and exploiting a buffer overrun vulnerability recently reported by Microsoft for the Windows operating system.
In these circumstances, if you have a buffer overrun because the system hasn't pushed the data onto tape fast enough, once the data has flown the 295 inches it has to go back and find its place again.
Protecting against somebody doing a buffer overrun in a shopping cart application should've been done when the application was written," he says.
The new intrusion prevention currently protects 22 applications and operating system components from known buffer overrun vulnerabilities, using signatures that secure against the vulnerability, not the exploit, Bedrick added.
The company claims that the Blaster worm has been spreading at a slower rate than CodeRed, Nimda or Slammer although the potential for infection is greater with Blaster as there are more machines that are vulnerable to the MS RPC Buffer Overrun vulnerability.
To be a geek for a moment, it is a buffer overrun in the IDA/IDQ ISAPI filter.
The Code Red worm takes advantage of a buffer overrun vulnerability, discovered last month, allowing the attacker to gain control over an affected server and deface websites, orchestrate denial of service attacks, reformat hard drives or perform other illegal acts.