A zero-day (or zero-hour) attack or threat is a computer threat that tries to exploit unknown, undisclosed or patchfree computer application vulnerabilities. The term Zero Day is also used to describe unknown or Zero day viruses.

Zero-day exploits are released before the vendor patch is released to the public. Zero-day exploits generally circulate through the ranks of attackers until finally being released on public forums. The term derives from the age of the exploit. A zero-day exploit is usually unknown to the public and to the product vendor

The term zero-day can also be used to describe warez-group releases of pirated software on or before the release of the software.

Answered by ani , an ibibo Advisor, at 12:43 PM on December 20, 2008

A zero-day exploit is one that takes advantage of a security vulnerability on the same day that the vulnerability becomes generally known. Ordinarily, after someone detects that a software program contains a potential exposure to exploitation by a hacker, that person or company can notify the software company and sometimes the world at large so that action can be taken to repair the exposure or defend against its exploitation. Given time, the software company can repair and distribute a fix to users. Even if potential hackers also learn of the vulnerability, it may take them some time to exploit it; meanwhile, the fix can hopefully become available first.

With experience, however, hackers are becoming faster at exploiting a vulnerability and sometimes a hacker may be the first to discover the vulnerability. In these situations, the vulnerability and the exploit may become apparent on the same day. Since the vulnerability isn't known in advance, there is no way to guard against the exploit before it happens. Companies exposed to such exploits can, however, institute procedures for early detection of an exploit.

A study released by Symantec in early 2004 found that although the number of vulnerabilities discovered was about the same in 2003 as in 2002, the time between the vulnerability and exploits based on it had narrowed. According to the infoAnarchy wiki, "14-day" groups and "7-day" groups carry out an exploit within 14 or 7 days of a product's market release. Conducting a zero-day exploit establishes crackers as members of the elite, because they must have covert industry connections to gain the inside information needed to carry out the attack.

Answered by Nishu%27s , an ibibo Master, at 11:59 AM on December 20, 2008

"This out-of-band security update is not cumulative," Microsoft officials stated in the advisory. "To be fully protected, customers should apply this update after applying the most recent cumulative security update for Internet Explorer. This update, MS08-078, will be included in a future cumulative security update for Internet Explorer."

Reports of attacks targeting the vulnerability began to surface the week of Dec. 8, and over the weekend, hackers were found to be compromising legitimate Web sites as part of their efforts to infect vulnerable users. McAfee reported Dec. 17 that a number of variants of the exploit are circulating, including one that uses malicious Word document files.

For those who cannot quickly deploy the patch, Microsoft has made information available about a number of workarounds and mitigations, including restricting Internet Explorer from using OLEDB32.dll with an Integrity Level ACL and disabling X M L Island functionality.

Answered by Manoj Mankar , an ibibo Advisor, at 9:49 AM on December 20, 2008

A zero day exploit is a malicious computer attack that takes advantage of a security hole before the vulnerability is known. This means the security issue is made known the same day as the computer attack is released. In other words, the software developer has zero days to prepare for the security breach and must work as quickly as possible to develop a patch or update that fixes the problem.

Zero day exploits may involve viruses, trojan horses, worms or other malicious code that can be run within a software program. While most programs do not allow unauthorized code to be executed, hackers can sometimes create files that will cause a program to perform functions unintended by the developer. Programs like Web browsers and media players are often targeted by hackers because they can receive files from the Internet and have access to system functions.

While most zero day exploits may not cause serious damage to your system, some may be able to corrupt or delete files. Because the security hole is made known the same day the attack is released, zero day exploits are difficult to prevent, even if you have antivirus software installed on your computer. Therefore, it is always good to keep a backup of your data in a safe place so that no hacker attack can cause you to lose your data.

Answered by Shishir , an ibibo Master, at 8:49 AM on December 20, 2008