Adversaries can hide a program's true filetype by changing the extension of a file. With certain file types (specifically this does not work with .app extensions), appending a space to the end of a filename will change how the file is processed by the operating system.
For example, if there is a Mach-O executable file called <code>evil.bin</code>, when it is double clicked by a user, it will launch Terminal.app and execute. If this file is renamed to <code>evil.txt</code>, then when double clicked by a user, it will launch with the default text editing application (not executing the binary). However, if the file is renamed to <code>evil.txt </code> (note the space at the end), then when double clicked by a user, the true file type is determined by the OS and handled appropriately and the binary will be executed (Citation: Mac Backdoors are back).
Adversaries can use this feature to trick users into double clicking benign-looking files of any format and ultimately executing something malicious.
View in MITRE ATT&CK®| Capability ID | Capability Description | Mapping Type | ATT&CK ID | ATT&CK Name | Notes |
|---|---|---|---|---|---|
| adaptive_application_controls | Adaptive Application Controls | technique_scores | T1036.006 | Space after Filename |
Comments
Once this control is activated, it generates alerts for any executable that is run and is not included in an allow list. Malicious files of this type would be unlikely to evade detection from any form of allow list. Events are calculated once every twelve hours, so its temporal score is Partial.
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