Create write.yml

yml/OSBinaries/write.yml

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+---
+Name: write.exe
+Description: 'Wrapper binary for launching wordpad. Historically it was used to launch Microsoft Write, a very basic word processor from pre-2000 era. Currently its left as a compatibility stub after Windows 95 onwards.'
+Author: Michal Belzak
+Created: 2025-06-17
+Commands:
+  - Command: write.exe
+    Description: 'Executes a binary provided in default value of (HKCU|HKLM):\Software\Microsoft\Windows\CurrentVersion\App Paths\wordpad.exe.'
+    Usecase: Execute binary through legitimate proxy. This might be utilized to confuse detection solutions that rely on parent-child relationships.
+    Category: Execute
+    Privileges: User
+    MitreID: T1218
+    OperatingSystem: Windows
+    Tags:
+      - Execute: EXE
+  - Command: write.exe
+    Description: 'It is possible to provide arguments by modifying HKCU:\Software\Classes\exefile\shell\open\command to include the following value: "%1" <args>'
+    Usecase: Execute binary through legitimate proxy. This might be utilized to confuse detection solutions that rely on parent-child relationships.
+    Category: Execute
+    Privileges: User
+    MitreID: T1218
+    OperatingSystem: Windows
+    Tags:
+      - Execute: EXE
+      - Execute: CMD
+  - Command: write.exe
+    Description: 'It is possible to execute remote binaries when using UNC path instead. This will display security prompt and fail in non-interactive environments. To offset for that, one needs to control a custom domain, be able to set A DNS record in it and register this record in `HKCU:\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\Domains\`. For details on bypass, refer to Resources.'
+    Usecase: Execute remote binary.
+    Category: Execute
+    Privileges: User
+    MitreID: T1218
+    OperatingSystem: Windows
+    Tags:
+      - Execute: Remote
+Full_Path:
+  - Path: 'C:\Windows\write.exe'
+  - Path: 'C:\Windows\System32\write.exe'
+  - Path: 'C:\Windows\SysWOW64\write.exe'
+Detection:
+  - IOC: 'Changes to HKCU:\Software\Microsoft\Windows\CurrentVersion\App Paths\wordpad.exe'
+  - IOC: 'Changes to HKCU:\Software\Classes\exefile\shell\open\command'
+  - IOC: '(related to UNC prompt bypass) Changes to HKCU:\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\Domains\'
+  - Sigma: https://github.com/SigmaHQ/sigma/blob/master/rules/windows/registry/registry_set/registry_set_persistence_app_paths.yml
+Resources:
+  - Link: https://gist.github.com/mblzk/b8c5ff7c2bd0fb2b385cc2fdd119874b
+Acknowledgement:
+  - Person: Michal Belzak