t1027-obfuscated-files-or-information

name	T1027_obfuscated-files-or-information
description	Adversaries may attempt to make an executable or file difficult to discover or analyze by encrypting, encoding, or otherwise obfuscating its contents on the system or in transit.
category	configuration
version	18.1
author	cyberstrike-official
tags	["mitre-attack","enterprise","t1027","defense-evasion","esxi","linux","macos","network-devices","windows"]
technique_id	T1027
tactic	defense-evasion
all_tactics	["defense-evasion"]
platforms	["ESXi","Linux","macOS","Network Devices","Windows"]
mitre_url	https://attack.mitre.org/techniques/T1027
tech_stack	["esxi","linux","macos","network devices","windows"]
cwe_ids	["CWE-693"]
chains_with	["T1027.001","T1027.002","T1027.003","T1027.004","T1027.005","T1027.006","T1027.007","T1027.008","T1027.009","T1027.010","T1027.011","T1027.012","T1027.013","T1027.014","T1027.015","T1027.016","T1027.017"]
prerequisites	[]
severity_boost	{"T1027.001":"Chain with T1027.001 for deeper attack path","T1027.002":"Chain with T1027.002 for deeper attack path","T1027.003":"Chain with T1027.003 for deeper attack path"}

T1027 Obfuscated Files or Information

High-Level Description

Adversaries may attempt to make an executable or file difficult to discover or analyze by encrypting, encoding, or otherwise obfuscating its contents on the system or in transit. This is common behavior that can be used across different platforms and the network to evade defenses.

Payloads may be compressed, archived, or encrypted in order to avoid detection. These payloads may be used during Initial Access or later to mitigate detection. Sometimes a user's action may be required to open and Deobfuscate/Decode Files or Information for User Execution. The user may also be required to input a password to open a password protected compressed/encrypted file that was provided by the adversary. Adversaries may also use compressed or archived scripts, such as JavaScript.

Portions of files can also be encoded to hide the plain-text strings that would otherwise help defenders with discovery. Payloads may also be split into separate, seemingly benign files that only reveal malicious functionality when reassembled.

Adversaries may also abuse Command Obfuscation to obscure commands executed from payloads or directly via Command and Scripting Interpreter. Environment variables, aliases, characters, and other platform/language specific semantics can be used to evade signature based detections and application control mechanisms.

Kill Chain Phase

• Defense Evasion (TA0005)

Platforms: ESXi, Linux, macOS, Network Devices, Windows

What to Check

• Identify if Obfuscated Files or Information technique is applicable to target environment
• Check ESXi systems for indicators of Obfuscated Files or Information
• Check Linux systems for indicators of Obfuscated Files or Information
• Check macOS systems for indicators of Obfuscated Files or Information
• Verify mitigations are bypassed or absent (4 known mitigations)
• Assess detection coverage (1 detection strategies)

How to Test

Atomic Red Team Tests

The following tests are from Atomic Red Team and provide actionable ways to test this technique:

Atomic Test 1: Decode base64 Data into Script

Creates a base64-encoded data file and decodes it into an executable shell script

Upon successful execution, sh will execute art.sh, which is a base64 encoded command, that echoes and uname -v