PC Hell: What is the ~ (tilde) file on my desktop?

The file appearing on your desktop with the filename ~, commonly known as a tilde, is a backup of your Windows Address Book. It is appearing as a result of the April 2003 Cumulative Patch for Outlook Express (330994). The patch is installed for Outlook Express 5.5 or 6 in response to a vulnerability that could allow an attacker to run code of the attacker’s choice on a user’s machine. To exploit the vulnerability, an attacker would have to be able to cause Windows to open a specially constructed MHTML URL, either on a web site or included in an HTML email message.

Unfortunately, there is a bug in the patch.Whenever you make a change in your Windows Address Book file (*.wab file), Windows makes a backup of this file. Generally this backup is called username.wa~ , however after the patch is installed the backup gets renamed to just ~ instead and saved in the directory where you start your Outlook Express. Most of the time, people start Outlook Express from a shortcut on their desktop, so the backup file gets placed there. This is how the tilde (~) file arrives on your desktop.

Because the file is simply a backup of your Windows Address Book, spyware searching utilities or anti-virus products wont flag it as anything suspicious.

The simple answer is yes, the file can be deleted. However if it is deleted, you wont have a backup of your Windows Address Book if a virus or something else corrupts it or you accidentally delete the information in the address book. So I wouldnt necessarily delete the file without backing it up first. Personally, here are the steps I would take to remain safe in case you need the file again.

Each time you make a change to your address book, this file will reappear so its a good idea to keep that floppy drive around and make a backup each time you make changes. This protects you from losing valuable email addresses in case of a disaster.

An alternative to this would be to change the Start in option for Outlook Express. This has been suggested by a few visitors and works well.

Although Microsoft has indicated that it knows about this problem and intends to make a patch available, they have not released one yet, as of July 2003.

UPDATE: Finally, in June 2004, Microsoft has released a hotfix for this issue. Visit this link for more information about this problem and a solution for it.

Yes, you can uninstall the patch, this will fix the tilde (~) file from appearing, however you will not be protected from this security vulnerability either. If you want to uninstall the April 2003 (330994) patch, simply visit this link and follow the uninstall directions. Although I wouldn't advise anyone doing this.

Outlook Express Backup Genie, a handy email backup utility that works with the top 9 popular Email Clients such as MS Outlook, Outlook Express, Eudora, Netscape Messenger, IncrediMail and PocoMail. It allows you to save your messages, address book, settings, mail and news accounts, message rules, blocked senders lists and the signatures, which can be easily restored when necessary.

How to Backup and Restore Outlook Express Mail, Address Book, Blocked Senders List and other Settings