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Hidden Executable File Creation Detection


The HiddenFileCreated signature targets the identification of furtive attempts to create hidden executable files, specifically ELF (Executable and Linkable Format) files, in the system. By convention, in Unix-like systems, any file or directory that starts with a dot (.) is hidden from standard directory listings.


Hidden files and directories are commonly used in Linux and Unix systems to store configuration files and user preferences. However, malicious actors can exploit this convention to hide their activities, files, and tools from standard monitoring and listing tools. The creation of a hidden ELF file, in particular, can suggest that an attacker or malicious software is attempting to operate undetected on the system.

The HiddenFileCreated signature closely watches for these furtive actions by scanning the file paths for the presence of the "hidden" pattern, i.e., starting with a "/.". Combined with checking the magic bytes of files to determine if they are ELF format, this signature provides a robust method to detect hidden executable file creation.


This signature's principal objective is to detect and flag the concealed creation of ELF files. Monitoring such actions is crucial since, while there can be legitimate reasons to have hidden executables, the unauthorized or unexpected creation of such files can be an early indication of malicious activities.


  • ID: TRC-1015
  • Version: 1
  • Name: Hidden executable creation detected
  • EventName: hidden_file_created
  • Description: The signature identifies the creation of hidden executable ELF files in the system. While there can be genuine reasons for having hidden executables, the unauthorized or unforeseen creation of such files can be indicative of malicious intent.
  • Properties:
  • Severity: 2 (Moderate threat level)
  • Category: defense-evasion
  • Technique: Hidden Files and Directories
  • Kubernetes_Technique: N/A
  • id: attack-pattern--ec8fc7e2-b356-455c-8db5-2e37be158e7d
  • external_id: T1564.001


When an anomaly is detected, the signature returns a Finding data structure, which comprises:

  • SigMetadata: Metadata that provides detailed information about the detected threat, based on the signature's definitions.
  • Event: An exhaustive description of the particular event that invoked the signature's alert mechanism.
  • Data: Currently initialized to nil, indicating that no additional data is associated with the alert.

Events Used

The primary event that powers this signature's functionality is:

  • magic_write: Triggered when specific byte sequences, or "magic bytes," are written to a file. The signature checks the bytes to see if they correspond to an ELF file and examines the file path to determine if the ELF file is hidden.