File Extensions Be Careful with Files Containing Multiple Extensions SUMMARY: Files with multiple extensions may be Trojan Horses waiting for you to open them and release their nefarious content. Be careful with these files.   Especially on the Internet and when looking at electronic mail attachments, such as inside spam emails, you may come across files with multiple extensions, such as: readme.txt.exe In this case, note that the final extension is the actual extension of the file. The "txt" is NOT the file's extension; it is "exe". This means that although you might think the file is a text file, based on the "txt" extension, the file is actually an executable, based on the "exe" extension. Thus, if you were to double-click this masquerading file, instead of getting a text document opened with Notepad, you would actually be running a problem. And, unfortunately, in this case, the program might be a dangerous Trojan horse (computer virus) that could do damage to your system or others'. Be VERY WARY of any file containing more than one extension! Although not true 100% of the time, much of the time files with multiple extensions were written to fool people into executing Trojan horses. To help ensure that you accurately see filenames that contain more than one extension, you should force Windows to view all file extensions.   Add: Del.icio.us | Digg | Furl | My Yahoo!   Discuss This Tip Print This Tip Get E-Mail When New Tips are Online Return to the File Extensions page.