Reborn Ace Hack

Suppose there is a situation where several melon seeds with different flavors are to be placed in a large box. The melon seeds with different flavors cannot be mixed, and the weight of each melon seed must be calculated very conveniently. What will we do?

There is a way to make many grids of the same size and isolated from each other in a box. The weight of melon seeds that can be stored in each grid is certain, assuming it is 50 grams. We put each type of melon seeds in these in turn.

In the grid, for example, five spices occupy five complete grids, but the sixth grid is not fully occupied.

If we want to know the weight of melon seeds, we only need to weigh the melon seeds in the sixth unfilled grid. If the weight accuracy is not high, we can even directly weigh the melon seeds in the last unfilled grid.

Melon seeds are also calculated as 50 grams. In this case, the calculation of the weight of melon seeds will be more convenient and faster.

According to this method, other flavors of melon seeds are stored starting from the seventh grid, and the weight is measured by counting the grids, and so on.

At this time, we only consider the grids with melon seeds. We have a problem. After we put all the melon seeds in the box, there will inevitably be many grids that are not occupied, which means that the space utilization rate is not 100%.

Well, we can call space that is wasted due to unused space fragments.

In a computer operating system, the functional module that manages disk files is called a file system. Although different file systems manage disk files in different ways, one thing is the same, that is, all file systems in the disk

When storing files, the disk storage space will be divided into grids of the same size. There is a term for this grid in the computer profession, called disk sectors. The process of drawing grids on the disk is what we usually call formatting.

Similar to the calculation of the weight of melon seeds, the file system's calculation of file size is generally based on sectors. If it is less than one sector, it will also be calculated on a sector basis.

It’s the same as putting melon seeds in a box as described earlier. Because the file size is random and cannot be exactly an integer multiple of the disk sector size, the disk space utilization rate of any file system cannot be 100%.

The unusable disk space is what we often call disk fragmentation.

Although the disk space consumed by each disk fragment is very small, we know that the number of files in the disk is extremely large, so the number of disk fragments is also extremely large. As a result, the huge number of disk fragments,

The cost of disk space is very considerable. These disk fragments will not only cause disk space lag

G fee also has a great impact on disk reading and writing efficiency. The reasons for this are relatively complicated and will not be discussed here. The ntfs used on the Internet has strong management capabilities for disk fragmentation and can greatly reduce the impact of disk fragmentation on space.

lang fee, a file system that is more advanced than ntfs, and can even become less and less fragmented as the disk is used over time.

However, the FAT32 used on Microsoft's operating system Windows 98 is a sluggish file system. This system has extremely weak management capabilities for disk fragmentation, so that as the disk is used over time, more and more fragments become used.

Then you have to use some external disk defragmentation tools to re-arrange the disk files to achieve the purpose of reducing disk fragmentation.

We usually think that disk fragments cannot be exploited, but some computer experts can use these fragments through some clever means to achieve their special purposes.

When a virus infects a disk file, it will generally cause the disk file to increase in size, but let's imagine if the virus file does not occupy new disk sectors when it infects the disk file, but stores itself in those areas that are not full of infected file data.

In the disk sector, and the file system calculates the disk file size in units of sectors, what will be the result?

This is easy to understand. At this time, although the virus file writes itself into the file, the size of the disk file does not change. This phenomenon is like pouring water into a bucket of sand.

The volume of sand in the bucket did not increase.

Gu Lang threw the paperclip into Meili's plate, and the paperclip fell into the gap between the CD cases. This was also the case.

Gu Lang thought further, because the file infected by the CIH virus itself uses this mechanism to store itself, and the virus prototype they obtained was also extracted from the disk fragments of the infected file, but he and everyone

They all overlooked one thing, that is, when the virus itself occupies disk fragments, it will also generate

New disk fragments, if the virus writers stuff the core code of the virus into the new disk fragments generated by these virus prototypes, and use some means to hide them, then they have previously carried out the

It is understandable that the mutated code cannot be found in disassembly and that specialized killing tools cannot clean the virus.

Hurrying back to the technical department, Gu Lang sat next to the computer and prayed secretly, hoping that his guess just now was correct.

He opened a disk data capture tool and grabbed all the data in the disk space where the virus was located, including fragments, and then compared it with the original virus file data, and got some

Differential data, these data have actually been obtained before, but they previously filtered out these data as junk data, but this time, he wanted to focus on analyzing this data.

Import these data into another data analysis software. When he started to analyze, Gu Lang's heart suddenly rose to his throat, because this was the only way he could think of. If this method still didn't work, he felt that he

Some people are really out of their depth.

With his eyes slightly closed, Gu Lang waited for a few minutes, then took a deep breath, slowly opened his eyes, and looked at the computer screen. The analysis results of the data analysis software had come out.

"So it's really like this, what a clever method!"

Gu Lang looked at the analysis report given by the software, and his heart suddenly dropped to his stomach. He clenched his fist and waved it in the air. Then he stood up and said loudly, "Everyone, come here and have a meeting!"

The employees of the technical department were gathered together again, and Gu Lang briefly explained his findings, which elicited another burst of exclamations.

"Wu Yang, don't worry about what this mutation algorithm is. Just clear the virus-infected disk sectors and use the fastest time to improve the virus-killing tool. The longer it takes, the worse it will be for us.

, let the meeting adjourn." Gu Lang ordered Wu Yang.

In fact, without Gu Lang's instructions, Wu Yang had been depressed for such a long time, and now he had a breakthrough. He couldn't wait and was eager to try it, so as soon as Gu Lang finished speaking, he left in a hurry with his two assistants.

After Wu Yang left, Gu Lang processed the mutation algorithm code of the virus he got, then disassembled it and got a piece of assembly code, so with deep curiosity, he began to analyze the code.

Research analysis.

This code is easy to understand. It contains a random mutation algorithm. It can be said that as long as this code cannot be found, then this mutation algorithm will generate a different one again once it detects that the CIH virus it generated has been killed.

The mutated virus came out. In addition, this code also includes a CIH virus immunity code judgment and bypass mechanism. This mechanism is not particularly clever. When Gu Lang was hired by Chi Xiang, he used it when dealing with Xiao Yuan.

through a similar method.

While he was studying this code, Wuyang was also working nervously. An hour later, a new version of the special killing tool was released. After testing, this time the special killing tool successfully removed the virus in the virtual machine.

Completely killed.

"Immediately send the special killing tool to the Network Department, publish it and upload it to the Xuannie Forum. I will go to Mr. Tang to report it now. Thank you for your hard work."

Gu Lang was a little excited at this time. He ordered Wu Yang, then hurriedly came out of the technical department, took a deep breath, and went to Tang Xinyu's office.