said by scottp99:... Are these more dangerous than an ordinary infection by a trojan or a worm or a virus? I dont quite understand. ...
No... a buffer overflow is a description of a system's legitimate software's flaw or weakness that may be attacked by an infection to get into the computer, not a measure of the infection seriousness itself, once it has gotten in. An infection is an infection, by whatever means of arrival. Once safely inside, an initial infector may invite any number of nasty friends in from outside or it may self-contain any manner of malicious "payloads"... it all depends on the coding attached to the initial infector.
However, an exploitable buffer overflow is a weakness existing within a legitimate piece of software installed on your system, and that
is grounds for continuing concern. It raises the chances for the same or some other exploit to attack that same vulnerability in some future encounter. So, if possible, you really should identify and plug that security hole, either by updating/patching the vulnerable software (preferred solution), by blocking the attack point within that software using some settings option in the software or the OS, or by making use of external protective software that responds to this kind of threat... or some combination of these.