Zero Day Attacks are attacks from viruses programed to exloit systems upon arrival.
Many viruses are created to make use of PCs or workstations on a given date and time but a zero day virus performs an attack the moment it arrives on a users system.
The most recent encountered example is an exploit in Adobe Flash Player. In particular this effects all released 10.0.x and 9.0.x versions of Flash, including the current version (10.0.45.2), are vulnerable.
In addition, because the vulnerable component is also used by Adobe’s PDF products, both Acrobat and Reader versions 9.3.2 and earlier that belong to the 9.x family are also affected. The previous 8.x versions of Acrobat and Reader are not affected.
Usually systems that are patched up to date are OK as many of these exploits rely on unpatched systems.
Many Anti-Virus programs rely on pattern file updates however Trend Micro users the Smart Protection Network. This is a central register of know Viruses and Trojans and is essencially a list that is queried each time a file is downloaded. This takes milliseconds and has no impact on system performance.
This list is updated in real-time by all Trend Micro Clients and is more efficient than pattern files ever could be. Zero-Day Attacks and Exploits are a prime example of why the Smart Protection Network is a better way to go.