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T1222 File and Directory Permissions Modification

Adversaries may modify file or directory permissions/attributes to evade access control lists (ACLs) and access protected files.23 File and directory permissions are commonly managed by ACLs configured by the file or directory owner, or users with the appropriate permissions. File and directory ACL implementations vary by platform, but generally explicitly designate which users or groups can perform which actions (read, write, execute, etc.).

Modifications may include changing specific access rights, which may require taking ownership of a file or directory and/or elevated permissions depending on the file or directory’s existing permissions. This may enable malicious activity such as modifying, replacing, or deleting specific files or directories. Specific file and directory modifications may be a required step for many techniques, such as establishing Persistence via Accessibility Features, Boot or Logon Initialization Scripts, Unix Shell Configuration Modification, or tainting/hijacking other instrumental binary/configuration files via Hijack Execution Flow.

Adversaries may also change permissions of symbolic links. For example, malware (particularly ransomware) may modify symbolic links and associated settings to enable access to files from local shortcuts with remote paths.84175

Item Value
ID T1222
Sub-techniques T1222.001, T1222.002
Tactics TA0005
Platforms Linux, Windows, macOS
Version 2.2
Created 17 October 2018
Last Modified 19 October 2022

Mitigations

ID Mitigation Description
M1026 Privileged Account Management Ensure critical system files as well as those known to be abused by adversaries have restrictive permissions and are owned by an appropriately privileged account, especially if access is not required by users nor will inhibit system functionality.
M1022 Restrict File and Directory Permissions Applying more restrictive permissions to files and directories could prevent adversaries from modifying their access control lists. Additionally, ensure that user settings regarding local and remote symbolic links are properly set or disabled where unneeded.9

Detection

ID Data Source Data Component
DS0026 Active Directory Active Directory Object Modification
DS0017 Command Command Execution
DS0022 File File Metadata
DS0009 Process Process Creation

References

  1. Falcon OverWatch Team. (2022, March 23). Falcon OverWatch Threat Hunting Contributes to Seamless Protection Against Novel BlackCat Attack. Retrieved May 5, 2022. ↩

  2. Hybrid Analysis. (2018, June 12). c9b65b764985dfd7a11d3faf599c56b8.exe. Retrieved August 19, 2018. ↩

  3. Hybrid Analysis. (2018, May 30). 2a8efbfadd798f6111340f7c1c956bee.dll. Retrieved August 19, 2018. ↩

  4. Kaspersky Global Research & Analysis Team (GReAT). (2022). A Bad Luck BlackCat. Retrieved May 5, 2022. ↩

  5. Microsoft. (2021, September 27). fsutil behavior. Retrieved January 14, 2022. ↩

  6. Netsurion. (2014, February 19). Monitoring File Permission Changes with the Windows Security Log. Retrieved August 19, 2018. ↩

  7. Pereira, T. Huey, C. (2022, March 17). From BlackMatter to BlackCat: Analyzing two attacks from one affiliate. Retrieved May 5, 2022. ↩

  8. Symantec Threat Hunter Team. (2021, December 16). Noberus: Technical Analysis Shows Sophistication of New Rust-based Ransomware. Retrieved January 14, 2022. ↩