T1027.014 Polymorphic Code

> Sub-technique of: T1027

High-Level Description

Adversaries may utilize polymorphic code (also known as metamorphic or mutating code) to evade detection. Polymorphic code is a type of software capable of changing its runtime footprint during code execution. With each execution of the software, the code is mutated into a different version of itself that achieves the same purpose or objective as the original. This functionality enables the malware to evade traditional signature-based defenses, such as antivirus and antimalware tools. Other obfuscation techniques can be used in conjunction with polymorphic code to accomplish the intended effects, including using mutation engines to conduct actions such as Software Packing, Command Obfuscation, or Encrypted/Encoded File.

Kill Chain Phase

• Defense Evasion (TA0005)

Platforms: Windows, macOS, Linux

What to Check

• ] Identify if Polymorphic Code technique is applicable to target environment
• ] Check Windows systems for indicators of Polymorphic Code
• ] Check macOS systems for indicators of Polymorphic Code
• ] Check Linux systems for indicators of Polymorphic Code
• ] Verify mitigations are bypassed or absent (2 known mitigations)
• ] Assess detection coverage (1 detection strategies)

How to Test

Manual Testing

1. Identify Attack Surface: Determine if the target environment is susceptible to Polymorphic Code by examining the target platforms (Windows, macOS, Linux).

1. Assess Existing Defenses: Review whether mitigations for T1027.014 are in place. If defenses are absent or misconfigured, this technique may be exploitable.

1. Execute Test: Use tools and methods described in the MITRE ATT&CK page and external references below.

> Note: No Atomic Red Team tests available for this technique. See Atomic Red Team GitHub for updates.

Remediation Guide

M1040 Behavior Prevention on Endpoint

On Windows 10+, enable Attack Surface Reduction (ASR) rules to prevent execution of potentially obfuscated payloads

M1049 Antivirus/Antimalware

Anti-virus can be used to automatically detect and quarantine suspicious files. Employment of advanced anti-malware techniques that make use of technologies like machine learning and behavior-based mechanisms to conduct signature-less malware detection will also be more effective than traditional indicator-based detection methods.

Detection

Detection Strategy for Polymorphic Code Mutation and Execution

Risk Assessment

| Finding | Severity | Impact | | ------------------------------------- | -------- | --------------- | | Polymorphic Code technique applicable | Medium | Defense Evasion |

CWE Categories

| CWE ID | Title | | ------- | ---------------------------- | | CWE-693 | Protection Mechanism Failure |

References

• polymorphic-blackberry
• polymorphic-sentinelone
• polymorphic-medium
• polymorphic-linkedin
• Atomic Red Team - T1027.014
• MITRE ATT&CK - T1027.014