The spyware is a program that captures statistic information from user´s computer and sends it over internet without user acceptance. This information is usually obtained from cookies and web browser’s history. The spyware can also install other software, display advertisement, or redirect the web browser activity. A spyware differs from virus, worm and adware from various ways. The spyware does not self-replicate and distribute like virus and worm, and not necessarily displays advertisements like adware. The common characteristics between spyware and virus, worm, and adware are:
1. exploitation of infected computer for commercial purposes
2. the display, in some cases, of advertisements
The spyware is usually masqueraded or presented as an utility software like P2P client, optimization tool, web accelerator, download accelerator, and even as security software like antispyware. In this case the user infects the computer by installing this kind of software without being aware of the danger. The spyware can also be bundled in media and shareware, being additionally installed with the software or autorun. The infection can occurs through fake Windows warning, when the fake message appears warning the user about some security issue or offering performance optimizing. The computer infected presents symptoms like poor performance due to high memory and processor usage, unwanted behavior, system crash, high internet bandwidth usage, large number of popup, and many other symptoms. The biggest problem is that the infected computer becomes extremely vulnerable to many other spywares, which install themselves into the computer.
Some Spywares are very dificult to remove because they can hide they-selfs into Browser Cookies and Offline HTML Content in Temporary files.
Figure 1. A lot of toolbars added by spyware, and some working as spyware
- http://cwe.mitre.org/data/definitions/506.html - Malicious