What causes the buffer overrun vulnerability?
The print spooler provides a number of APIs that allow users to request or configure printing services. However, several of these APIs have unchecked buffers. The unchecked buffers could be exploited in two ways. In the simplest case, a malicious user could simply provide random data as an argument to an affected function in order to crash the print spooler service. An administrator would need to restart the spooler service, but in most cases would not need to reboot the machine. A more advanced attack could involve providing a specially-malformed argument to an affected API in it could be used to cause arbitrary code to run on the server in a System context. An important point regarding this vulnerability is the fact that most of the affected APIs can only be called by members of the Administrators and Power Users groups. Only a few can be called by normal users.
