T1222
File and Directory Permissions Modification
Description from ATT&CK
Adversaries may modify file or directory permissions/attributes to evade access control lists (ACLs) and access protected files.(Citation: Hybrid Analysis Icacls1 June 2018)(Citation: Hybrid Analysis Icacls2 May 2018) 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.(Citation: new_rust_based_ransomware)(Citation: bad_luck_blackcat)(Citation: falconoverwatch_blackcat_attack)(Citation: blackmatter_blackcat)(Citation: fsutil_behavior)
Atomic Tests
Atomic Test #1 - Enable Local and Remote Symbolic Links via fsutil
Use fsutil to enable both ‘remote to local’ and ‘remote to remote’ symbolic links. This allows access to files from local shortcuts with local or remote paths. reference
Supported Platforms: windows
auto_generated_guid: 6c4ac96f-d4fa-44f4-83ca-56d8f4a55c02
Inputs:
None
Attack Commands: Run with command_prompt! Elevation Required (e.g. root or admin)
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fsutil behavior set SymlinkEvaluation R2L:1
fsutil behavior set SymlinkEvaluation R2R:1
Cleanup Commands:
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fsutil behavior set SymlinkEvaluation R2L:0
fsutil behavior set SymlinkEvaluation R2R:0