China DOS Union

Can everyone tell me the principle of antivirus software? I suddenly want to learn about it, heh

You've studied really deeply!

No, you flatter me.
It's because I don't know how, so I'm asking for advice.

Probably, it is to first read the virus signature code library, and then scan each file one by one. If a certain part (usually the end part) of a file matches a certain virus signature code, the virus signature code of this file will be cleared.

As the upstairs said, indeed, but now many viruses can be added to a file without making the file abnormal (the file occupies the same space), so the antivirus software is to compare the entire file's occupied sectors and then compare according to the virus signature!

The first generation of anti-virus technology adopted simple virus signature judgment to remove viruses from infected files. This method can accurately remove viruses and has high reliability. Later, with the development of virus technology, especially the application of encryption and polymorphism technology, this simple static scanning method became ineffective. Then the anti-virus technology also developed a step further.

The second generation of anti-virus technology adopts the static broad-spectrum signature scanning method to detect viruses. This method can detect more polymorphic viruses, but on the other hand, the false positive rate also increases. Especially, the risk of removing viruses with this loose signature judgment method is very high, which is easy to cause damage to files and data. So the static anti-virus technology also has insurmountable defects.

The main feature of the third generation of anti-virus technology is to combine static scanning technology with dynamic simulation tracking technology, integrate virus detection and virus removal into one, form an overall solution, and can fully realize various necessary means for anti-virus such as prevention, detection, and removal. It prevents virus intrusion by resident in memory, and can remove any detected virus without damaging files and data. With the increase in the number of viruses and the development of new virus technologies, the static scanning technology will slow down the virus detection software, and the resident memory anti-virus module is prone to false positives.

The fourth generation of anti-virus technology is based on the development of computer viruses, based on the naming rules of virus family systems, based on multi-bit CRC checksum scanning mechanism, heuristic intelligent code analysis module, dynamic data restoration module (can detect viruses in highly hidden compressed and encrypted files), memory detoxification module, self-immune module and other advanced detoxification technologies, which well solve the situation where previous anti-virus technologies were unable to give equal attention to different aspects.

Reprinted from: "http://www.jijiao.com.cn/leafbak/Vintro/Vknow/00000013.htm"

You'd better ask the antivirus company.

Great stuff! Learned a lot! Thanks!

Can you introduce how to use legitimate antivirus software for free! And the kind that can be upgraded intelligently!

It seems that only Kingsoft Anti-Virus can be completely cracked.