Exploit Computer Security

An exploit is a common term in the computer security community to refer to a piece of software that takes advantage of a bug, glitch or vulnerability, leading to privilege escalation or denial of service on a computer system.

There are several methods of classifying exploits. The most common is by how the exploit contacts the vulnerable software. A 'remote exploit' works over a network and exploits the security vulnerability without any prior access to the vulnerable system. A 'local exploit' requires prior access to the vulnerable system and usually increases the privileges of the person running the exploit past those granted by the system administrator. Exploits against client applications also exist, usually consisting of modified servers that send an exploit if accessed with client application. Exploits against client applications may also require some interaction with the user and thus be used in combination with social engineering methods.

Exploits can also be classified by the type of vulnerability they attack. See buffer overflow, integer overflow, memory corruption, format string attacks, race condition, cross-site scripting, cross-site request forgery and SQL injection bugs.

Another classification is by the action against vulnerable system: unauthorized data access, code execution, denial of service.

Many exploits are designed to provide root-level access to a computer system. However, it is also possible to use several exploits, first to gain low-level access, then to escalate privileges repeatedly until one reaches root.

Normally a single exploit can only take advantage of a specific software vulnerability. Often, when an exploit is published, the vulnerability is fixed and the exploit becomes obsolete for newer versions of the software. This is the reason why some blackhat hackers do not publish their exploits but keep them private to themselves or other malicious hackers. Such exploits are referred to as 'zero day exploits' and to obtain access to such exploits is the primary desire of unskilled malicious attackers, the so called script kiddies.

This article is adapted from: wikiPedia.com