T1546.001: Change Default File Association
| View on MITRE ATT&CK | T1546.001 |
|---|---|
| Tactic(s) | Privilege Escalation, Persistence |
| Associated CAPEC Patterns | Replace File Extension Handlers (CAPEC-556) |
Data from MITRE ATT&CK®:
Adversaries may establish persistence by executing malicious content triggered by a file type association. When a file is opened, the default program used to open the file (also called the file association or handler) is checked. File association selections are stored in the Windows Registry and can be edited by users, administrators, or programs that have Registry access or by administrators using the built-in assoc utility.(Citation: Microsoft Change Default Programs)(Citation: Microsoft File Handlers)(Citation: Microsoft Assoc Oct 2017) Applications can modify the file association for a given file extension to call an arbitrary program when a file with the given extension is opened.
System file associations are listed under HKEY_CLASSES_ROOT.[extension], for example HKEY_CLASSES_ROOT.txt. The entries point to a handler for that extension located at HKEY_CLASSES_ROOT\[handler]. The various commands are then listed as subkeys underneath the shell key at HKEY_CLASSES_ROOT\[handler]\shell\[action]\command. For example:
HKEY_CLASSES_ROOT\txtfile\shell\open\commandHKEY_CLASSES_ROOT\txtfile\shell\print\commandHKEY_CLASSES_ROOT\txtfile\shell\printto\command
The values of the keys listed are commands that are executed when the handler opens the file extension. Adversaries can modify these values to continually execute arbitrary commands.(Citation: TrendMicro TROJ-FAKEAV OCT 2012)
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MITRE ATT&CK Data Components
Windows Registry Key Modification (Windows Registry)
Changes made to a Registry Key and/or Key value (ex: Windows EID 4657 or Sysmon EID 13|14)Command Execution (Command)
The execution of a line of text, potentially with arguments, created from program code (e.g. a cmdlet executed via powershell.exe, interactive commands like >dir, shell executions, etc. )Process Creation (Process)
The initial construction of an executable managed by the OS, that may involve one or more tasks or threads. (e.g. Win EID 4688, Sysmon EID 1, cmd.exe > net use, etc.)Control Validation Tests for this Technique
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