Hide Artifacts: Hidden Files and Directories

Adversaries may set files and directories to be hidden to evade detection mechanisms. To prevent normal users from accidentally changing special files on a system, most operating systems have the concept of a ‘hidden’ file. These files don’t show up when a user browses the file system with a GUI or when using normal commands on the command line. Users must explicitly ask to show the hidden files either via a series of Graphical User Interface (GUI) prompts or with command line switches (dir /a for Windows and ls –a for Linux and macOS).

On Linux and Mac, users can mark specific files as hidden simply by putting a "." as the first character in the file or folder name [1] [2]. Files and folders that start with a period, ‘.’, are by default hidden from being viewed in the Finder application and standard command-line utilities like "ls". Users must specifically change settings to have these files viewable.

Files on macOS can also be marked with the UF_HIDDEN flag which prevents them from being seen in Finder.app, but still allows them to be seen in Terminal.app [3]. On Windows, users can mark specific files as hidden by using the attrib.exe binary. Many applications create these hidden files and folders to store information so that it doesn’t clutter up the user’s workspace. For example, SSH utilities create a .ssh folder that’s hidden and contains the user’s known hosts and keys.

Adversaries can use this to their advantage to hide files and folders anywhere on the system and evading a typical user or system analysis that does not incorporate investigation of hidden files.

ID: T1564.001
Sub-technique of:  T1564
Tactic: Defense Evasion
Platforms: Linux, Windows, macOS
Permissions Required: User
Defense Bypassed: Host forensic analysis
Version: 1.0
Created: 26 February 2020
Last Modified: 29 March 2020

Procedure Examples

ID Name Description
S0331 Agent Tesla

Agent Tesla has created hidden folders.[4]

S0584 AppleJeus

AppleJeus has added a leading . to plist filenames, unlisting them from the Finder app and default Terminal directory listings.[5]

G0007 APT28

APT28 has saved files with hidden file attributes.[6][6]

G0050 APT32

APT32's macOS backdoor hides the clientID file via a chflags function.[7]

S0438 Attor

Attor can set attributes of log files and directories to HIDDEN, SYSTEM, ARCHIVE, or a combination of those.[8]

S0475 BackConfig

BackConfig has the ability to set folders or files to be hidden from the Windows Explorer default view.[9]

S0274 Calisto

Calisto uses a hidden directory named .calisto to store data from the victim’s machine before exfiltration.[10][11]

S0484 Carberp

Carberp has created a hidden file in the Startup folder of the current user.[12]

S1043 ccf32

ccf32 has created a hidden directory on targeted systems, naming it after the current local time (year, month, and day).[13]

S0660 Clambling

Clambling has the ability to set its file attributes to hidden.[14]

S0369 CoinTicker

CoinTicker downloads the following hidden files to evade detection and maintain persistence: /private/tmp/.info.enc, /private/tmp/.info.py, /private/tmp/.server.sh, ~/Library/LaunchAgents/.espl.plist, ~/Library/Containers/.[random string]/[random string].[15]

S0497 Dacls

Dacls has had its payload named with a dot prefix to make it hidden from view in the Finder application.[16][17]

S0634 EnvyScout

EnvyScout can use hidden directories and files to hide malicious executables.[18]

S0569 Explosive

Explosive has commonly set file and path attributes to hidden.[19]

G1016 FIN13

FIN13 has created hidden files and folders within a compromised Linux system /tmp directory. FIN13 also has used attrib.exe to hide gathered local host information.[20][21]

S0277 FruitFly

FruitFly saves itself with a leading "." to make it a hidden file.[22]

G0125 HAFNIUM

HAFNIUM has hidden files on a compromised host.[23]

S0278 iKitten

iKitten saves itself with a leading "." so that it's hidden from users by default.[22]

S0434 Imminent Monitor

Imminent Monitor has a dynamic debugging feature to set the file attribute to hidden.[24]

S0260 InvisiMole

InvisiMole can create hidden system directories.[25]

S0015 Ixeshe

Ixeshe sets its own executable file's attributes to hidden.[26]

S0162 Komplex

The Komplex payload is stored in a hidden directory at /Users/Shared/.local/kextd.[1]

G0032 Lazarus Group

Lazarus Group has used a VBA Macro to set its file attributes to System and Hidden and has named files with a dot prefix to hide them from the Finder application.[27][16][17][28]

S0447 Lokibot

Lokibot has the ability to copy itself to a hidden file and directory.[29]

S0451 LoudMiner

LoudMiner has set the attributes of the VirtualBox directory and VBoxVmService parent directory to "hidden".[30]

G1014 LuminousMoth

LuminousMoth has used malware to store malicious binaries in hidden directories on victim's USB drives.[31]

S0409 Machete

Machete has the capability to exfiltrate stolen data to a hidden folder on a removable drive.[32]

S0282 MacSpy

MacSpy stores itself in ~/Library/.DS_Stores/ [33]

S0339 Micropsia

Micropsia creates a new hidden directory to store all components' outputs in a dedicated sub-folder for each.[34]

G0129 Mustang Panda

Mustang Panda's PlugX variant has created a hidden folder on USB drives named RECYCLE.BIN to store malicious executables and collected data.[35]

S0198 NETWIRE

NETWIRE can copy itself to and launch itself from hidden folders.[36]

S0439 Okrum

Before exfiltration, Okrum's backdoor has used hidden files to store logs and outputs from backdoor commands.[37]

S0402 OSX/Shlayer

OSX/Shlayer has executed a .command script from a hidden directory in a mounted DMG.[38]

S0352 OSX_OCEANLOTUS.D

OSX_OCEANLOTUS.D sets the main loader file’s attributes to hidden.[39]

S0013 PlugX

PlugX can modify the characteristics of folders to hide them from the compromised user.[40]

S0428 PoetRAT

PoetRAT has the ability to hide and unhide files.[41]

S0650 QakBot

QakBot has placed its payload in hidden subdirectories.[42]

S0262 QuasarRAT

QuasarRAT has the ability to set file attributes to "hidden" to hide files from the compromised user's view in Windows File Explorer.[43]

S0448 Rising Sun

Rising Sun can modify file attributes to hide files.[44]

G0106 Rocke

Rocke downloaded a file "libprocesshider", which could hide files on the target system.[45][46]

S0533 SLOTHFULMEDIA

SLOTHFULMEDIA has been created with a hidden attribute to insure it's not visible to the victim.[47]

S0663 SysUpdate

SysUpdate has the ability to set file attributes to hidden.[48]

S0595 ThiefQuest

ThiefQuest hides a copy of itself in the user's ~/Library directory by using a . at the beginning of the file name followed by 9 random characters.[49]

G0134 Transparent Tribe

Transparent Tribe can hide legitimate directories and replace them with malicious copies of the same name.[50]

G0081 Tropic Trooper

Tropic Trooper has created a hidden directory under C:\ProgramData\Apple\Updates\ and C:\Users\Public\Documents\Flash\.[51][52]

S0366 WannaCry

WannaCry uses attrib +h to make some of its files hidden.[53]

S0612 WastedLocker

WastedLocker has copied a random file from the Windows System32 folder to the %APPDATA% location under a different hidden filename.[54]

S0658 XCSSET

XCSSET uses a hidden folder named .xcassets and .git to embed itself in Xcode.[55]

Mitigations

This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.

Detection

ID Data Source Data Component Detects
DS0017 Command Command Execution

Monitor the file system and shell commands for files being created with a leading "." and the Windows command-line use of attrib.exe to add the hidden attribute.

DS0022 File File Creation

Monitor the file system and shell commands for files being created with a leading "."

File Metadata

Monitor for contextual data about a file, which may include information such as name, the content (ex: signature, headers, or data/media), user/owner, permissions may set files and directories to be hidden to evade detection mechanisms.

DS0009 Process Process Creation

Monitor newly executed processes that may set files and directories to be hidden to evade detection mechanisms.

References

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