CHM Files and Security Risks
With the advent of web based help formats, CHM files may not be a widely used as they used to. That said, there are still many that use them. Just search your hard drive and you’ll soon see more than a few. The trouble is that if the posts on the various authoring forums are anything to go by, they can cause problems for some.
Most of the problems are security related, especially after Microsoft Security Update 896358. This update identified that running a CHM file posed a security threat and as such could not be run on a network drive. This is covered in full on Peter Grainge’s website together with the workarounds you can use. Apart from only have CHMs on a local drive that is.
Similar problems can also occur where a CHM has been passed to a third party and installed on a local drive. Users complain that they are unable to see the topic content. Instead they get a message “Navigation to the webpage was cancelled”. This is also a security related issue but is easily solved.
- Right click on the file to display a popup menu.
- Click Properties to display the File Properties dialog.
- Click the Unblock button.
- Click OK.
The Unblock button is displayed if the file has been produced on another PC and is therefore flagged as a potential security risk. Clicking Unblock says you are happy that there is no security risk imposed by the file, therefore make sure you are happy with the content before doing so.
