What if the CHM file cannot be opened?

Source: Internet
Author: User
Tags microsoft website



Recently, I often heard from my friends that I could not open the CHM file, and I often encountered it. After searching online, I will summarize the Methods:
1. If the file cannot be opened, you can restore the file association as follows:
1. Start running. Enter regsvr32 c: \ windows \ system32 \ hhctrl. ocx. OK. Re-associate the file.
2. Execute hh.exe in the Windows directory.
Sometimes the CHM file cannot be placed in the Chinese directory. Including the Chinese CHM name. Try to test the file. Change the Chinese name.

2.1.download hhupd.exeon the Microsoft website, install hh.exe, and run it.
2. Download hhupd.exe and run it. The size of this item is 461kb 3. in c: \ windows \ system32, find "hhctrl. ocx file, and then run: "regsvr32" C: \ windows \ system32 \ hhctrl. OCX...
The network cannot be resolved, and hhupd.exe cannot be downloaded. I will directly execute regsvr32 c: \ windows \ system32 \ hhctrl. ocx and it will be OK.

Solution 2:
1. Right-click to associate the "open mode" of the CHM File to \ windows \ hh.exe
2. Run regsvr32 itss. dll on the command line.
3. Run regsvr32 hhctrl. ocx on the command line.

3. It may be that a component necessary for HH. EXE has a problem. But I don't know what components will be used by HH. EXE, so I checked it online. Someone suggested registering hhctrl. ocx again. I found hhctrl. ocx IN THE SYSTEM directory and registered hhctrl. ocx again. Try: regsvr32 hhctrl. ocx. Still cannot read CHM normally.

In this case, it is very likely that there is a problem with the protocol. HH. EXE uses MS-its and other protocols. These protocols should be provided by a DLL file. The problem is, what is the DLL? Then Google searches for the MS-its protocol. Finally, it turns out that it is an itss. dll service. However, the solution found on the Internet is to modify the registry.

To modify the itssrestrictions registry to enable a specific security zone, follow these steps:
1. Click Start, click Run, type regedit, and click OK ".
2. Locate and click the following subitem:
HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ htmlhelp \ 1. x \ itssrestrictions
Note: If the registry subitem does not exist, use steps 2a and 2b in method 1 to create the subitem.
3. Right-click the "itssrestrictions" subitem, point to "new", and click "DWORD Value ".
4. Type maxallowedzone and press Enter.
5. Right-click the value of "maxallowedzone" and click "modify ".
6. In the value data box, type a number between 0 and 4, and click OK ".
7. Exit the Registry Editor.
Note: by default, the value of "maxallowedzone" is set to 0. The following table summarizes the explanations of maxallowedzone values for each item. Maxallowedzone local computer area Local intranet area trusted site area Internet area restricted site area
0. Allow blocking.
1. Allow blocking and blocking
2. Allow Blocking
3. Allow and allow Blocking
4. Allow and allow

The registry cannot be opened after modification!
Try the lazy method -- re-register dll: regsvr32 itss. dll.

4. The operating system language is not Chinese (this is often the case)
1. Check whether your OS is a Chinese OS? If your OS is not Chinese, go to control pane to check the option of "language and region" and check whether "region option" is China, this option still has images for some software.
2. If your CHM File is Chinese, the default language may be incorrect. You may use Windows in English version to set the language and country options in language and advanced in ragional and language options to Chinese (PRC ). You can.

5. Try changing the file name, for example, removing unnecessary symbols.

6. If neither of them can be used, the last trick is to convert the chm format of the e-book into a PDF file:
CHM converter is a file that converts CHM files into common formats such as PDF, txt, and Doc.

Run the software after downloading. Default Value:


The system version is XP SP2.
Problem: The CHM file cannot be displayed when it is opened.
Purpose: To give new beginners like me a new idea. I wish my younger brother Zhang Yinzhou a successful academic career and a happy life.

It is estimated that few people have encountered this problem. At that time, I did not know what I had changed. Let's just talk about the idea.
First, Jinzhou went online to find relevant information. Find a valuable article.

"Files in chm format cannot be displayed, and files in Windows 2000 are normal. After files are opened on Windows XP, the page cannot be found.

I tried it on my Windows XP. It's strange, but my CHM e-books are all good. Although I told the user that there was a problem with the Help file, I still solved the problem. Alas, it's also a record of all the similar problems we 've encountered before, and none of them are correct. The result is that after the ERP department finds the vendor consultation, the ERP vendor gives the solution. The original thing was as follows:

Some CHM files may use the Infotech protocol, which contains three protocols: MS-its, its, MK: @ msitstore. Using these protocols, malicious attackers or malicious code may cause an overflow vulnerability to help control computers. The latest MS Security Update MS05-026 kb896358 corrected this situation and blocked remote links, which led to failure to enable some CHM pages using remote links. The vulnerability is described as follows:

This security issue comes from the Microsoft HTML Help vulnerability announced earlier. HTML help is a standard help system on Windows. The author can use it to create online help files for programs, multimedia themes, or websites.
Because HTML help does not fully validate the features of input data, this may be exploited. A special CHM file can cause the help system to overflow. If this overflow is exploited, it can be used to execute malicious code.
Such malicious CHM files can be enabled through ie using the "MS-its" protocol. The opened CHM file can automatically execute malicious CHM files and accompanying code without the user's participation. The MS-its protocol is part of the Infotech protocol, which can be executed by itss. dll or Microsoft InfoTech Storage System Library. Of course, these malicious programs cannot be spread by themselves, and users still need to access malicious CHM files at specific locations through IE and "MS-its" protocols.
In this case, if the current logon identity of the affected user is administrator, the remote code execution vulnerability can allow malicious users or malware to gain full control of the affected system.
This allows the malicious user or program to execute code on the system, install or run the program with full control permissions, and view or edit data. Therefore, this vulnerability can also be used for replication.

Affected Systems:

Microsoft Windows 2000 Service Pack 3
Microsoft Windows 2000 Service Pack 4
Microsoft Windows 98
Microsoft Windows 98 Second Edition
Microsoft Windows Millennium Edition
Microsoft Windows Server 2003
Microsoft Windows XP Service Pack 1
Microsoft Windows XP Service Pack 2
Microsoft Windows Server 2003 for itanium-based systems
Microsoft Windows XP-bit Edition Service Pack 1 (itanium)
Microsoft Windows XP-bit Edition Version 2003 (itanium)
Microsoft Windows XP Professional x Edition
Microsoft Windows Server 2003 Service Pack 1
Microsoft Windows Server 2003 with SP1 for itanium-based systems
Microsoft Windows Server 2003 x Edition

After installing Windows Server 2003 Service Pack 1, MS05-026 or MS04-023, I made the following modifications to the client registry as described in some Web applications that use the Infotech protocol, the CHM files are successfully executed again!

[HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ htmlhelp \ 1. x \ itssrestrictions]
& Quot; urlallowlist & quot ;=& quot ;\\\ helpfiles \; file: // \\\ helpfiles & quot;

Note that, by default, there may be no itssrestrictions child keys in child Jian 1.x. You need to manually create it and then create the string key value urlallowlist under it.

For details about the patch and related issues, refer to the following KB:

Some Web applications that use the Infotech Protocol cannot be used after installing Windows Server 2003 Service Pack 1, MS05-026 or MS04-023
MS05-026: vulnerabilities in HTML Help may allow remote code execution
The compiled help module file downloaded after installing security update 896358 cannot be opened"

My problem is obviously not this problem, because my own machine knows that when the CHM file can be opened, to open the CHM File
The page cannot be displayed during this period. I did not update it, but made some system modifications.
However, this article has inspired me, for example, the Infotech protocol. The preceding description ends.
Although there are many articles about this on the Internet, you can search for them by yourself, but I didn't find any solutions to my problems,

So I decided to enter the test. The following is the Golden State Test method: (The problem is very simple, mainly about the ideas, Golden State notes)
1. Jinzhou creates a restore point for the current status that cannot be displayed when the CHM file is opened.
2. regsnap takes a snapshot.
3. Import the previously backed up registry.
As a result, the CHM file is opened as before, so that you can view the file normally.
Golden State is summarized as the cause of some registry project loss.
4. Repeat regsnap and take another snapshot.
I found that there were too many projects (I backed up the Registry earlier, haha) and I could not make a detailed judgment.
This road is broken.
5. After sitting around for about ten minutes, I suddenly remembered the Infotech protocol "MS-its". This is the article I found.
Haha, the execution file of this protocol is c: \ windows \ system32 \ itss. dll.
6. Check that the DLL is still in process. Therefore, the second assumption is that the associated Call Registry is lost.
7. Start testing the above inference. Search for registry-related itss. dll items. This list is not suitable for listing.
8. Back up all related projects.
9. Restore the system to the status when the CHM cannot be opened.
10. Import the backup itss. dll project. You can view the CHM File and solve the problem. Verify that the guess is correct and find the cause.
11. The status cannot be displayed after the CHM is restored to enabled.
12. Test each registry project one by one, so that the loop continues until the key items are identified.
13. Finally, two key projects are identified. As follows:
Project 1.
Windows Registry Editor Version 5.00

[Hkey_classes_root \ CLSID \ {9d148291-b9c8-11d0-a4cc-rjf80149f6}]
@ = & Quot; Microsoft InfoTech protocols for IE 4.0 & quot;

[Hkey_classes_root \ CLSID \ {9d148291-b9c8-11d0-a4cc-rjf80149f6} \ inprocserver32]
@ = & Quot; C: \ Windows \ system32 \ itss. dll & quot;
& Quot; threadingmodel & quot; = & quot; both & quot;

[Hkey_classes_root \ CLSID \ {9d148291-b9c8-11d0-a4cc-rjf80149f6} \ notinsertable]

[Hkey_classes_root \ CLSID \ {9d148291-b9c8-11d0-a4cc-rjf80149f6} \ versionindependentprogid]
@ = & Quot; msitfs & quot;

Project 2.
Windows Registry Editor Version 5.00

[Hkey_classes_root \ Protocols \ name-space Handler \ MK \ *]
& Quot; CLSID & quot; = & quot; {9d148291-b9c8-11d0-a4cc-417f80149f6} & quot;
14. Conclusion: The problem is indeed the loss of the Infotech Protocol Registry Association.

Note 1. This method may not be suitable for solving similar problems, because the cause of the problem is the sequela of my personal modification of the system.
It mainly provides a simple idea.
2. My personal problems in this article were found in Jinzhou on the afternoon of-. After the solution was completed in the evening, I sent the solution to some forums.
The day before yesterday, I saw some of my friends asking questions in the post I posted, without having to think about and test it.
I hope it will be helpful to some friends.
3. I always think about it when I encounter problems. 1. Have I tried my best? 2. Have I carefully searched and understood the relevant materials? 3. I
Have you tried various possibilities? This is my stupid method of benzene. Haha, I wish my younger brother Zhang Yinzhou a successful academic career.
Be happy. And bless everyone.

Time: 17:08:18

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