Unable to open a .NULL file? We collect information about file formats and can explain what NULL files are. Furthermore, we recommend appropriate software to open or convert these files.

What is the .NULL file type?

In Apple’s commercial operating system Mac OS X, the dot-separated ” .null ” string represents a hidden filename, rather than an extension. Along with several other names, such as .jupd ate, .rser v, and others, it is related to Flashback malware that affects Apple Mac OS X through a Java security hole.

On a Mac OS X system, the presence of the .null file ( .jupd ate, etc.) in the user’s home directory is a sign of Flashback infection. This file is a Mac OS X executable. Due to the attack point, it is treated as a hidden file, not visible in the default Finder mode. Created in the background on a vulnerable Mac OS X system when a malicious Java-based website is visited, the .null file ( .jupd ate, etc.) serves as a malware download agent that downloads and activates malicious code real. Flashback is known to steal personal and financial information and send it to remote servers.

The Flashback issue has been investigated by Apple, and a patched version of Java and automated malware removal tools have been released for Mac OS X users. Internet Flashback.

In some cases, the .null extension is assigned to various media files, such as images or audio files, as part of their processing by online or local applications. Conditioned either by misconfiguration or software bugs, this behavior is anomalous, and the .null extension is just a placeholder. If the original file format is known or can be determined, these affected files should be individually or collectively renamed using the appropriate file type (eg, “.jpg” instead of ” .null “).

Also, the .null filename extension is used in JP .Boll back’s Stochastic Mutational Mapping on Phylogenies (SIMMAP) software to denote unprocessed files containing statistical data with null or predictive values, generated in the part of a SIMMAP analysis cycle. In addition to these .null files , the software also uses files containing observed values, which receive the extension .obs.

Finally, the .null extension can be assigned to device-related files called NULL (/dev/null on Unix-like operating systems), a virtual “black hole” sink for digital data. These .null files can simply be symlinks pointing to the /dev/null device.

How to Troubleshoot NULL Files


Right-click on any NULL file and then click “Open with” > “Choose another app”.
Now select another program and check the box “Always use this app to open *.NULL files”.


Right-click (or hold down the Ctrl key) the NULL file, then click “Open with” > “Other…”. Then choose another program and check the “Always Open With” box.


Right-click on the file, select “Open with” and choose another program.


Tap the file. If you don’t see an app to open the file, tap Share “Share” and choose an app. Otherwise, save the file. Next, open the Files app Files app. Long-press the file, then release your finger. You will see a black menu bar. Then tap “Share” and select an app.


Touch the Settings icon on your smartphone, then touch the Applications section. Tap the Options icon in the top right corner of the screen to change default apps.
Update your software that should really open NULL is NULL image. Because only the current version supports the latest NULL file format.

To ensure that your NULL file is not corrupted or infected with a virus, recover it again and scan it using anti-virus software.