The code could take any action on the machine that the user himself could take. The chief mitigating factor associated with this vulnerability is the requirement for the malicious user to entice a user into either opening the malformed PowerPoint 2000 file, visiting a malicious website, or viewing a specially crafted html email message. A parsing function executed by PowerPoint when a file is opened is subject to a buffer overrun vulnerability. If the file contained a particular type of malformed data, code could be made to run on the computer, or PowerPoint itself could be made to fail, via a buffer overrun vulnerability. Let s start with what a buffer is.
Buffers are storage areas within programs, and are frequently used to store program inputs.
As a matter of good coding practice, a program should always check the length of an input it s been provided before writing it to the buffer. Otherwise, an input value that s longer than the buffer could be written, thereby overrunning the buffer and overwriting nearby data. When a buffer overrun occurs, it can cause either of two results. In most cases, the data that spills out of the buffer has the effect of causing the program to fail. However, if the data is specially chosen, it can be used to alter what the program does.