Misunderstanding of Personal Computer Security: virus found in Cache

Misunderstanding of Personal Computer Security: virus found in Cache

Virus found in Cache

Like no virus in CMOS, There is no virus in Cache.

We know that the data stream is transmitted as follows during program execution:

External Storage (soft/hard disk)

Network => memory (RAM) => Cache-> CPU

The Cache physical device is a high-speed Cache chip, which is set between RAM and CPU and is a necessary channel from RAM to CPU. Because the CPU computing speed is getting faster and faster, and the computer's memory (RAM) speed is always unable to keep up with the CPU. "To reduce the speed conflict between the CPU and RAM, a Cache chip is usually used to add a Cache chip between them, the code prepared by RAM for the CPU at the same time is no longer a single command/data, but a long sequence of commands or accessible data blocks.

It can be seen that the non-static data stored in the Cache ("data" in computer terms includes "program code") is constantly refreshed as the program is executed, and the data in RAM is constantly changed. Its content is always a backup of a part of RAM data.

If a virus exists in RAM, the virus code is sent to the CPU through the Cache, Which is decoded and executed by the CPU. Virus code "flows through" Cache. This phenomenon cannot be called "Cache virus", as if we cannot execute the virus code in the CPU and think there is a CPU virus. In fact, according to the composition principle of the PC, all viruses must enter the CPU through the Cache, because all normal or abnormal data enters the CPU for decoding and execution.

In addition, one of the important reasons why the Cache cannot contain viruses is that the Cache cannot be edited by software and cannot be manually controlled.

Unlike CMOS, the Cache does not have a dedicated power supply. Therefore, the data in the Cache will be automatically cleared after shutdown, and automatically refreshed upon startup. In such an environment, viruses cannot be stored and copied. It can be seen that the Cache is not a virus nest, and no one will consider setting viruses in such an environment.